Articoli di riviste: "Arthropoda – Anatomy"

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Naumann, Benjamin, Hans S. Reip, Nesrine Akkari, David Neubert e Jörg U. Hammel. "Inside the head of a cybertype – three-dimensional reconstruction of the head muscles of Ommatoiulus avatar (Diplopoda: Juliformia: Julidae) reveals insights into the feeding movements of Juliformia". Zoological Journal of the Linnean Society 188, n. 4 (28 novembre 2019): 954–75. http://dx.doi.org/10.1093/zoolinnean/zlz109.

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Abstract The origin and diversification of the arthropod head is one of the major topics in the field of evolutionary morphology of Arthropoda. Among the major arthropod groups, Myriapoda and, more precisely Diplopoda, are generally poorly studied regarding their head anatomy. However, this group is of pivotal importance to understand the evolutionary functional morphology of the arthropod head. In this study, we investigate the complete musculoskeletal system of the diplopod head with a detailed description of the cephalic anatomy of the recently described species Ommatoiulus avatar. The comparison of our data with the literature on the few other species available show that the morphology of the musculoskeletal system within Juliformia, a subgroup of the Diplopoda, is relatively conservative. Using video recordings of the feeding movements in addition to the anatomical data, we revise the mechanism of the mandibular movements in Juliformia. There was a controversy whether mandibular abduction is an active process, facilitated by contraction of an abductor muscle, or if it is a passive process, mediated by tentorial and gnathochilarial movements not involving a direct abduction by muscular contraction. We show that mandibular abduction in Ommatoiulus is an active movement involving the contraction of an abductor muscle. This is similar to the mandibular abduction in other arthropod groups.

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ARANGO, CLAUDIA P., e AMY MAXMEN. "Proboscis ornamentation as a diagnostic character for the Anoplodactylus californicus-digitatus complex (Arthropoda: Pycnogonida) with an example from the Anoplodactylus eroticus female". Zootaxa 1311, n. 1 (11 settembre 2006): 51. http://dx.doi.org/10.11646/zootaxa.1311.1.3.

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Females of the Indo-Pacific species Anoplodactylus eroticus (Arthropoda: Pycnogonida: Phoxichilidiidae) are described for the first time. The presence of peculiar ventral outgrowths or protuberances on the female proboscis of A. eroticus and 13 other Anoplodactylus species motivates an evaluation of a californicus-digitatus complex, based on external morphology and species distribution. The anatomy and development of proboscis protuberances is assessed using scanning electron microscopy (SEM), Nomarski optics, and flourescence microscopy. External morphology of A. eroticus is compared to that of apparently related species. An identification key for the 14 species of Anoplodactylus with females bearing a proboscis with ventral protuberances is provided here as an identification tool.

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SHU, DEGAN, JEAN VANNIER, HUILIN LUO, LING CHEN, XINGLIANG ZHANG e SHIXUE HU. "Anatomy and lifestyle of Kunmingella (Arthropoda, Bradoriida) from the Chengjiang fossil Lagerstätte (lower Cambrian; Southwest China)". Lethaia 32, n. 4 (29 marzo 2007): 279–98. http://dx.doi.org/10.1111/j.1502-3931.1999.tb00547.x.

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STEIN, MARTIN, JOHN S. PEEL, DAVID J. SIVETER e MARK WILLIAMS. "Isoxys (Arthropoda) with preserved soft anatomy from the Sirius Passet Lagerstätte, lower Cambrian of North Greenland". Lethaia 43, n. 2 (7 settembre 2009): 258–65. http://dx.doi.org/10.1111/j.1502-3931.2009.00189.x.

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García-Bellido, Diego C., e Desmond H. Collins. "A new study of Marrella splendens (Arthropoda, Marrellomorpha) from the Middle Cambrian Burgess Shale, British Columbia, Canada". Canadian Journal of Earth Sciences 43, n. 6 (1 giugno 2006): 721–42. http://dx.doi.org/10.1139/e06-012.

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Study of over 1000 specimens of Marrella splendens Walcott, 1912, out of the more than 9000 collected by the Royal Ontario Museum (ROM) since 1975, has produced new information on the anatomy, functional morphology, and behaviour of this most common arthropod in the Burgess Shale fauna. Among the new features recognized is the distinction between the alimentary canal and circulatory system; where the former is generally three-dimensional and slightly reflective, the latter never presents any relief and is very reflective. A larger range of size is now known, from 2.4 to 24.5 mm in length, with small individuals possessing 17 body segments to large specimens with more than 26 body segments, representing an almost complete ontogenetic series. The second pair of "antennae" is now interpreted as swimming appendages, since the five distal segments are dorsoventrally compressed, fringed with setae and with a considerable blood supply, providing a paddlelike appendage capable of producing a considerable propelling force. The ROM collections extend the geographical distribution of Marrella 13 km to the southeast and the stratigraphical range through the lowest five members of the Burgess Shale Formation.

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Petrunina, Alexandra S., Gregory A. Kolbasov e Pedro Martinez Arbizu. "Anatomy of the free tantulus larva (Crustacea: Tantulocarida) studied with confocal laser scanning microscopy: An extreme case of miniatuarisation in the Arthropoda". Progress in Oceanography 178 (novembre 2019): 102190. http://dx.doi.org/10.1016/j.pocean.2019.102190.

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Budd, Graham E. "Arthropods from North Greenland: exceptional data in the ‘Cambrian explosion’ debate". Paleontological Society Special Publications 6 (1992): 44. http://dx.doi.org/10.1017/s2475262200006043.

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'Sirius Passet’ fauna arthropods from the Lower Cambrian Buen Formation of North Greenland form the major component of this exceptionally preserved biota. Early mineralisation of body cavities led to internal anatomy being preserved more readily than external structures such as limbs. Musculature and gut are known in three dimensional form. Many of the taxa present are more easily compared to extant arthropods than to flattened fossil material such as from the Burgess Shale.The most common arthropod is represented by some 1600 specimens. Although widely differing in preservational style, these specimens may be reconciled to provide a coherent model of the three-dimensional anatomy of the arthropod. The affinities of this arthropod lie with the ‘Cheliceromorph’ rather than the Crustacean biramous-limbed arthropods, and may represent a fairly advanced lineage within the clade.Recent discussions of the patterns produced by the early metazoan radiations have concentrated on data available from the Burgess Shale. The continuing discovery and description of other Cambrian lagerstätten such as from North Greenland and Chengjiang has highlighted the degree to which the Burgess Shale fauna should be considered to be an aliquot taken from the foment of the ‘Cambrian Explosion’. The discovery of more taxa is tending to flesh out the bare bones of the Burgess fauna. Conclusions about phylogentic patterns drawn from the Burgess Shale alone may thus be premature.Body patterning in the arthropods, and the validity of the ‘Bauplan’ concept may be investigated by consideration of the actual mechanisms available for profound morphological change. One promising route is provided by the ‘homeotic’ and other hierarchically arranged developmental genes. When the mode of action of these genes is considered in conjunction with phylogenetic methods, it may prove possible to assess evolutionary pathways in terms of the feasibility of the morphological changes required by them rather than relying on what seems inherently reasonable or on marginal advantages in parsimony. Exceptionally preserved biotas also contain the evidence for the evolution of the developmental mechanisms themselves.

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Solórzano Kraemer, Mónica M., Xavier Delclòs, Matthew E. Clapham, Antonio Arillo, David Peris, Peter Jäger, Frauke Stebner e Enrique Peñalver. "Arthropods in modern resins reveal if amber accurately recorded forest arthropod communities". Proceedings of the National Academy of Sciences 115, n. 26 (7 maggio 2018): 6739–44. http://dx.doi.org/10.1073/pnas.1802138115.

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Amber is an organic multicompound derivative from the polymerization of resin of diverse higher plants. Compared with other modes of fossil preservation, amber records the anatomy of and ecological interactions between ancient soft-bodied organisms with exceptional fidelity. However, it is currently suggested that ambers do not accurately record the composition of arthropod forest paleocommunities, due to crucial taphonomic biases. We evaluated the effects of taphonomic processes on arthropod entrapment by resin from the plantHymenaea, one of the most important resin-producing trees and a producer of tropical Cenozoic ambers and Anthropocene (or subfossil) resins. We statistically compared natural entrapment byHymenaea verrucosatree resin with the ensemble of arthropods trapped by standardized entomological traps around the same tree species. Our results demonstrate that assemblages in resin are more similar to those from sticky traps than from malaise traps, providing an accurate representation of the arthropod fauna living in or near the resiniferous tree, but not of entire arthropod forest communities. Particularly, arthropod groups such as Lepidoptera, Collembola, and some Diptera are underrepresented in resins. However, resin assemblages differed slightly from sticky traps, perhaps because chemical compounds in the resins attract or repel specific insect groups. Ground-dwelling or flying arthropods that use the tree-trunk habitat for feeding or reproduction are also well represented in the resin assemblages, implying that fossil inclusions in amber can reveal fundamental information about biology of the past. These biases have implications for the paleoecological interpretation of the fossil record, principally of Cenozoic amber with angiosperm origin.

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Weihmann, Tom, Hanns Hagen Goetzke e Michael Günther. "Requirements and limits of anatomy-based predictions of locomotion in terrestrial arthropods with emphasis on arachnids". Journal of Paleontology 89, n. 6 (novembre 2015): 980–90. http://dx.doi.org/10.1017/jpa.2016.33.

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AbstractModern computer-aided techniques foster the availability and quality of 3D visualization and reconstruction of extinct and extant species. Moreover, animated sequences of locomotion and other movements find their way into motion pictures and documentary films, but also gain attraction in science. While movement analysis is well advanced in vertebrates, particularly in mammals and birds, analyses in arthropods, with their much higher variability regarding general anatomy and size, are still in their infancies and restricted to a few laboratory species. These restrictions and deficient understanding of terrestrial arthropod locomotion in general impedes sensible reconstruction of movements in those species that are not directly observable (e.g., extinct and cryptic species). Since shortcomings like over-simplified approaches to simulate arthropod locomotion became obvious recently, in this review we provide insight into physical, morphological, physiological, behavioral, and ecological constraints, which are essential for sensible reconstructions of terrestrial arthropod locomotion. Such concerted consideration along with sensible evaluations of stability and efficiency requirements can pave the way to realistic assessment of leg coordination and body dynamics.

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PAGE, ALEX, PHILIP R. WILBY, MARK WILLIAMS, JEAN VANNIER, JEREMY R. DAVIES, RICHARD A. WATERS e JAN A. ZALASIEWICZ. "Soft-part preservation in a bivalved arthropod from the Late Ordovician of Wales". Geological Magazine 147, n. 2 (3 novembre 2009): 242–52. http://dx.doi.org/10.1017/s0016756809990045.

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AbstractA new component of the Early Palaeozoic arthropod fauna is described from a monospecific accumulate of carapaces in a Late Ordovician (Katian) hemipelagic mudstone from the Cardigan district of southwest Wales (UK). Its non-biomineralized carapace is preserved as a carbonaceous residue, as is more labile anatomy (soft-parts) including the inner lamella and sub-ovate structures near its antero-dorsal margin, which we interpret to be putative eyes. The depositional context and associated fauna indicate that the arthropods inhabited an area of deep water and high primary productivity above a pronounced submarine topography. The preserved density of carapaces suggests the arthropods may have congregated into shoals or been transported post-mortem into depressions which acted as detritus traps. The accumulate provides a rare example of soft-part preservation in hemipelagic mudstones and highlights the role of organic material as a locus for authigenic mineralization during metamorphism.

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WILLIAMS, MARK, THIJS R. A. VANDENBROUCKE, VINCENT PERRIER, DAVID J. SIVETER e THOMAS SERVAIS. "A link in the chain of the Cambrian zooplankton: bradoriid arthropods invade the water column". Geological Magazine 152, n. 5 (5 marzo 2015): 923–34. http://dx.doi.org/10.1017/s0016756815000059.

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AbstractBradoriids are small bivalved arthropods that had global distribution for about 20 million years beginning at Cambrian Epoch 2 (c. 521 Ma). The majority of bradoriids are considered to be benthic, favouring oxygenated waters, as suggested by their anatomy, lithofacies distribution, faunal associates and provinciality. Most bradoriids were extinct by the end of the Drumian Age (middle of Cambrian Epoch 3). The post-Drumian is characterized by widespread dysoxic shelf lithofacies in southern Britain and Scandinavia and by the abundance of phosphatocopid arthropods. This interval is also associated with two bradoriid species with wide intercontinental distribution: Anabarochilina primordialis, which had a geographical range from the palaeo-tropics to high southern palaeo-latitude, and Anabarochilina australis, which extended through the palaeo-tropics from Laurentia to Gondwana. The wide environmental and geographical range of these species, coupled with a carapace anatomy that suggests an active lifestyle, is used to infer a zooplanktonic lifestyle. A possible driver of this widespread Cambrian bradoriid zooplankton was sea-level rise coupled to the periodic spread of low oxygen conditions onto continental shelves, acting in tandem with anatomical pre-adaptations for swimming. Parallels exist with the myodocope ostracod colonization of the water column during Silurian time, which may also have been influenced by extrinsic environmental controls acting on anatomical pre-adaptations for swimming. Similar biological and environmental mechanisms may have facilitated arthropod zooplankton colonizations across Phanerozoic time.

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Bronson, D. D., H. J. Bidmon, K. H. Tomaschko e W. E. Stumpf. "Novel applications of acrylamide for cryosectioning of isolated cells, tissues, and arthropods." Journal of Histochemistry & Cytochemistry 39, n. 9 (settembre 1991): 1289–93. http://dx.doi.org/10.1177/39.9.1918945.

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Cross-linked and uncross-linked acrylamide polymers were used to alleviate technical difficulties in cryosectioning and autoradiographic processing of marine arthropods (Pycnogonum litorale), larval insect tissues (Sarcophaga bullata), and amphibian (Xenopus laevis) oocytes. Rapidly polymerized cross-linked acrylamide was used to prepare sections from an animal with a hard thick cuticle, P. litorale. Fragmentation and compression artifacts caused by tissue density differences were avoided and internal tissues were well preserved. Our results indicate that closely applied external support eliminates difficulties typically associated with arthropod cryosectioning. Pre-polymerized, uncross-linked acrylamide provided similar protection when used for sectioning larval tissue from S. bullata. Soft tissues under the cuticle were undamaged in tracheal and epidermal preparations. This polymer was also an excellent embedding material for soft tissues such as salivary glands, quickly penetrating tissue cavities and eliminating air bubbles. Uncross-linked acrylamide was used as an embedding and culturing medium for oocytes from X. laevis. The polymers were non-toxic and allowed the preparation of thin frozen sections containing as many as 50 large oocytes per section.

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Fu, Dongjing, e Xingliang Zhang. "A new arthropod Jugatacaris agilis n. gen. n. sp. from the Early Cambrian Chengjiang biota, South China". Journal of Paleontology 85, n. 3 (maggio 2011): 567–86. http://dx.doi.org/10.1666/09-173.1.

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A new arthropod Jugatacaris agilis n. gen. n. sp. with excellent soft anatomy is reported from the Early Cambrian Chengjiang biota. Its “bivalved” carapace with a dorsal fin-like fusion is distinct from those of other Cambrian arthropods. A pair of stalked eyes and a prominent median eye protrudes the carapace anteriorly. The cephalon, attaching to the carapace through the lateral adductor muscles at maxillary segment, bears an antennule, antenna and mandible. The trunk is comprised of a large number of segments (varying from 55 to 65), two-thirds of which is covered by the carapace. Each segment, except for the posterior three to five, carries a pair of uniform biramous appendages. The endopodite is composed of 30 podomeres and a terminal claw. The oar-shaped exopododite is fringed with filaments and distally bears a broad setiferous lobe. Trunk terminates with a conical telson and a pair of broad furcal rami serving as steering devices. Internal features like gonad and gut have also been found. The presence of the food groove combined with other morphological features indicates that Jugatacaris was a filter feeder. The appendages design associated with the overall body-plan supports the view that Jugatacaris is a crustaceanomorph. The accurate phylogenic assessment will remain the subject of debate until more information becomes available.

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Bertone, M. A., I. Miko, M. J. Yoder, K. C. Seltmann, J. P. Balhoff e A. R. Deans. "Matching arthropod anatomy ontologies to the Hymenoptera Anatomy Ontology: results from a manual alignment". Database 2013 (9 gennaio 2013): bas057. http://dx.doi.org/10.1093/database/bas057.

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Emerson, Michael J., e Frederick R. Schram. "A Novel Hypothesis for the Origin of Biramous Appendages in Crustaceans". Short Courses in Paleontology 3 (1990): 157–76. http://dx.doi.org/10.1017/s2475263000001781.

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Phylogenetic Uncertainty.— Invertebrate zoologists have long debated the relationships of biramous-limbed Crustacea to other groups of arthropods. Haeckel (1866) recognized two groups of arthropods on the basis of respiratory anatomy. The Carides included the crustaceans, trilobites, xiphosures, and eurypterids; and the Tracheata, included the arachnids, insects, and myriapods. Work on the onychophorans (Mosely, 1874) indicated a link between annelids and the terrestrial myriapod-insect line, but this left the origins of the aquatic carides unresolved. Lankester (1881) demonstrated that the xiphosures were allied to the arachnids rather than to the crustaceans. These and other studies led Haeckel (1896) to revise his position and propose two separate lines of arthropods: one of primarily aquatic groups with primitively biramous appendages (crustaceans, trilobites, and chelicerates); and the other of primarily terrestrial groups with uniramous limbs (onychophorans, myriapods, and insects). Haeckel's new arrangement emphasized the convergent origins of trachea in the arachnids and uniramians. Korschelt and Heider (1890) preferred a monophyletic scheme with the two evolutionary lines united by a pre-onychophoran, “protostracan,” ancestor. By modern standards, however, this might indicate that the arthropods are a morphological grade, rather than a true clade.

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Di Giulio, Andrea, e Maurizio Muzzi. "Two novel approaches to study arthropod anatomy by using dualbeam FIB/SEM". Micron 106 (marzo 2018): 21–26. http://dx.doi.org/10.1016/j.micron.2017.12.007.

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Lane, Nancy J. "Arthropod fine structure: Towards an understanding of the intricacies of intercellular junctions". Micron and Microscopica Acta 17, n. 2 (gennaio 1986): 137–47. http://dx.doi.org/10.1016/0739-6260(86)90043-2.

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Ramírez, Martín J., e Peter Michalik. "The Spider Anatomy Ontology (SPD)—A Versatile Tool to Link Anatomy with Cross-Disciplinary Data". Diversity 11, n. 10 (22 ottobre 2019): 202. http://dx.doi.org/10.3390/d11100202.

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Spiders are a diverse group with a high eco-morphological diversity, which complicates anatomical descriptions especially with regard to its terminology. New terms are constantly proposed, and definitions and limits of anatomical concepts are regularly updated. Therefore, it is often challenging to find the correct terms, even for trained scientists, especially when the terminology has obstacles such as synonyms, disputed definitions, ambiguities, or homonyms. Here, we present the Spider Anatomy Ontology (SPD), which we developed combining the functionality of a glossary (a controlled defined vocabulary) with a network of formalized relations between terms that can be used to compute inferences. The SPD follows the guidelines of the Open Biomedical Ontologies and is available through the NCBO BioPortal (ver. 1.1). It constitutes of 757 valid terms and definitions, is rooted with the Common Anatomy Reference Ontology (CARO), and has cross references to other ontologies, especially of arthropods. The SPD offers a wealth of anatomical knowledge that can be used as a resource for any scientific study as, for example, to link images to phylogenetic datasets, compute structural complexity over phylogenies, and produce ancestral ontologies. By using a common reference in a standardized way, the SPD will help bridge diverse disciplines, such as genomics, taxonomy, systematics, evolution, ecology, and behavior.

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Hallberg, Eric, e Bill S. Hansson. "Arthropod sensilla: Morphology and phylogenetic considerations". Microscopy Research and Technique 47, n. 6 (15 dicembre 1999): 428–39. http://dx.doi.org/10.1002/(sici)1097-0029(19991215)47:6<428::aid-jemt6>3.0.co;2-p.

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Zhang, Xingliang, e Degan Shu. "Soft anatomy of sunellid arthropods from the Chengjiang Lagerstutte, Lower Cambrian of southwest China". Journal of Paleontology 81, n. 6 (novembre 2007): 1412–22. http://dx.doi.org/10.1666/06-031r.1.

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Two bivalved arthropods of the family Sunellidae Huo, 1965 are described from the Lower Cambrian Helinpu Formation of southwestern China: Sunella cf. shensiensis Huo, 1965 and Combinivalvula chengjiangensis Hou, 1987. Both taxa preserve soft anatomies, described here for the first time, including a pair of lateral eyes and a possible median eye, a trunk carrying flaplike appendages, and a simple gut with caeca. The family Sunellidae includes three genera: Sunella Huo, Combinivalvula Hou, and Jinningella Huo and Shu. In contrast to most other Cambrian arthropods with a larger bivalved carapace, especially those from the Burgess Shale–type deposits, sunellids lack a limbless abdomen protruding posteriorly beyond the carapace. This, coupled with a combination of a number of snared features (e.g., the presence of cardinal spines and distinctive anterodorsal sulcus, elongated valves, and median eye), appears to support sunellids as a clade. The distinctive anterodorsal sulcus extending from the anterodorsal corner to the anteromedian part of the carapace is regarded as an autapomorphy for this clade. Sunellids resemble Isoxys Walcott, 1890 to which they may be closely related; both possess a bivalved, elongated carapace with cardinal spines that almost entirely covers the body. However, neither cephalic appendages nor proximal portions of trunk limbs are visible in sunellids, and thus, their systematic position remains uncertain.

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Stange, Gert, e Sally Stowe. "Carbon-dioxide sensing structures in terrestrial arthropods". Microscopy Research and Technique 47, n. 6 (15 dicembre 1999): 416–27. http://dx.doi.org/10.1002/(sici)1097-0029(19991215)47:6<416::aid-jemt5>3.0.co;2-x.

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Panina, Irina V., Mikhail B. Potapov e Alexey A. Polilov. "Effects of miniaturization in the anatomy of the minute springtail Mesaphorura sylvatica (Hexapoda: Collembola: Tullbergiidae)". PeerJ 7 (13 novembre 2019): e8037. http://dx.doi.org/10.7717/peerj.8037.

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Smaller animals display pecular characteristics related to their small body size, and miniaturization has recently been intensely studied in insects, but not in other arthropods. Collembola, or springtails, are abundant soil microarthropods and form one of the four basal groups of hexapods. Many of them are notably smaller than 1 mm long, which makes them a good model for studying miniaturization effects in arthropods. In this study we analyze for the first time the anatomy of the minute springtail Mesaphorura sylvatica (body length 400 µm). It is described using light and scanning electron microscopy and 3D computer reconstruction. Possible effects of miniaturization are revealed based on a comparative analysis of data from this study and from studies on the anatomy of larger collembolans. Despite the extremely small size of M. sylvatica, some organ systems, e.g., muscular and digestive, remain complex. On the other hand, the nervous system displays considerable changes. The brain has two pairs of apertures with three pairs of muscles running through them, and all ganglia are shifted posteriad by one segment. The relative volumes of the skeleton, brain, and musculature are smaller than those of most microinsects, while the relative volumes of other systems are greater than or the same as in most microinsects. Comparison of the effects of miniaturization in collembolans with those of insects has shown that most of the miniaturization-related features of M. sylvatica have also been found in microinsects (shift of the brain into the prothorax, absent heart, absence of midgut musculature, etc.), but also has revealed unique features (brain with two apertures and three pairs of muscles going through them), which have not been described before.

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Lane, Nancy J. "Novel arthropod cell junctions with restrictive intercellular ?linkers?" Journal of Neurocytology 18, n. 5 (ottobre 1989): 661–69. http://dx.doi.org/10.1007/bf01187085.

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De Vivo, Giacinto, Stephan Lautenschlager e Jakob Vinther. "Three-dimensional modelling, disparity and ecology of the first Cambrian apex predators". Proceedings of the Royal Society B: Biological Sciences 288, n. 1955 (21 luglio 2021): 20211176. http://dx.doi.org/10.1098/rspb.2021.1176.

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Radiodonts evolved to become the largest nektonic predators in the Cambrian period, persisting into the Ordovician and perhaps up until the Devonian period. They used a pair of large frontal appendages together with a radial mouth apparatus to capture and manipulate their prey, and had evolved a range of species with distinct appendage morphologies by the Early Cambrian (approx. 521 Ma). However, since their discovery, there has been a lack of understanding about their basic functional anatomy, and thus their ecology. To explore radiodont modes of feeding, we have digitally modelled different appendage morphologies represented by Anomalocaris canadensis , Hurdia victoria , Peytoia nathorsti, Amplectobelua stephenensis and Cambroraster falcatus from the Burgess Shale. Our results corroborate ideas that there was probably a significant (functional and hence behavioural) diversity among different radiodont species with adaptations for feeding on differently sized prey (0.07 cm up to 10 cm). We argue here that Cambroraster falcatus appendages were suited for feeding on suspended particles rather than filtering sediment. Given the limited dexterity and lack of accessory feeding appendages as seen in modern arthropods, feeding must have been inefficient and ‘messy’, which may explain their subsequent replacement by crown-group arthropods, cephalopods and jawed vertebrates.

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Oliveira, Ivo de Sena, Andreas Kumerics, Henry Jahn, Mark Müller, Franz Pfeiffer e Georg Mayer. "Functional morphology of a lobopod: case study of an onychophoran leg". Royal Society Open Science 6, n. 10 (ottobre 2019): 191200. http://dx.doi.org/10.1098/rsos.191200.

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Segmental, paired locomotory appendages are a characteristic feature of Panarthropoda—a diversified clade of moulting animals that includes onychophorans (velvet worms), tardigrades (water bears) and arthropods. While arthropods acquired a sclerotized exoskeleton and articulated limbs, onychophorans and tardigrades possess a soft body and unjointed limbs called lobopods, which they inherited from Cambrian lobopodians. To date, the origin and ancestral structure of the lobopods and their transformation into the jointed appendages are all poorly understood. We therefore combined high-resolution computed tomography with high-speed camera recordings to characterize the functional anatomy of a trunk lobopod from the onychophoran Euperipatoides rowelli . Three-dimensional reconstruction of the complete set of muscles and muscle fibres as well as non-muscular structures revealed the spatial relationship and relative volumes of the muscular, excretory, circulatory and nervous systems within the leg. Locomotory movements of individual lobopods of E. rowelli proved far more diverse than previously thought and might be governed by a complex interplay of 15 muscles, including one promotor, one remotor, one levator, one retractor, two depressors, two rotators, one flexor and two constrictors as well as muscles for stabilization and haemolymph control. We discuss the implications of our findings for understanding the evolution of locomotion in panarthropods.

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Eriksson, Mats E., Fredrik Terfelt, Rolf Elofsson e Federica Marone. "Internal Soft-Tissue Anatomy of Cambrian ‘Orsten’ Arthropods as Revealed by Synchrotron X-Ray Tomographic Microscopy". PLoS ONE 7, n. 8 (1 agosto 2012): e42582. http://dx.doi.org/10.1371/journal.pone.0042582.

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Feldmann, Rodney M., Carrie E. Schweitzer, Shixue Hu, Jinyuan Huang, Changyong Zhou, Qiyue Zhang, Wen Wen, Tao Xie, Frederick R. Schram e Wade T. Jones. "Earliest occurrence of lophogastrid mysidacean arthropods (Crustacea, Eucopiidae) from the Anisian Luoping Biota, Yunnan Province, China". Journal of Paleontology 91, n. 1 (5 dicembre 2016): 100–115. http://dx.doi.org/10.1017/jpa.2016.121.

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Abstract (sommario):

AbstractTiny, pelagic arthropods from the Anisian Luoping Biota exposed in two quarries near Luoping, Yunnan Province, China, represent the numerically most abundant organisms in the assemblage. They form the basis for definition of two, and possibly three, species referred to the order Lophogastrida, family Eucopiidae.Yunnanocopia grandisnew genus new species andY.longicaudan. gen. new species represent the oldest occurrence of mysidaceans in the fossil record. Their anatomy allies them with the Ladinian speciesSchimperella acanthocercusTaylor, Schram, and Shen, 2001, from Guizhou Province, China, which previously was thought to be the oldest lophogastrid, and with extant species of Eucopiidae. Their appearance in the Anisian represents one additional element of the early faunal radiation within the Luoping Biota following the end-Permian extinction event. Presence of well-preserved oostegites, along with other morphological features, documents a conservative bauplan expressed in Eucopiidae.

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Watson, Alan Hugh David. "Presynaptic modulation of sensory neurons in the segmental ganglia of arthropods". Microscopy Research and Technique 58, n. 4 (15 agosto 2002): 262–71. http://dx.doi.org/10.1002/jemt.10135.

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29

Köhler, Heinz-R. "Localization of metals in cells of saprophagous soil arthropods (Isopoda, Diplopoda, Collembola)". Microscopy Research and Technique 56, n. 5 (21 febbraio 2002): 393–401. http://dx.doi.org/10.1002/jemt.10039.

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30

Butler, Aodhán D., John A. Cunningham, Graham E. Budd e Philip C. J. Donoghue. "Experimental taphonomy of Artemia reveals the role of endogenous microbes in mediating decay and fossilization". Proceedings of the Royal Society B: Biological Sciences 282, n. 1808 (7 giugno 2015): 20150476. http://dx.doi.org/10.1098/rspb.2015.0476.

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Abstract (sommario):

Exceptionally preserved fossils provide major insights into the evolutionary history of life. Microbial activity is thought to play a pivotal role in both the decay of organisms and the preservation of soft tissue in the fossil record, though this has been the subject of very little experimental investigation. To remedy this, we undertook an experimental study of the decay of the brine shrimp Artemia , examining the roles of autolysis, microbial activity, oxygen diffusion and reducing conditions. Our findings indicate that endogenous gut bacteria are the main factor controlling decay. Following gut wall rupture, but prior to cuticle failure, gut-derived microbes spread into the body cavity, consuming tissues and forming biofilms capable of mediating authigenic mineralization, that pseudomorph tissues and structures such as limbs and the haemocoel. These observations explain patterns observed in exceptionally preserved fossil arthropods. For example, guts are preserved relatively frequently, while preservation of other internal anatomy is rare. They also suggest that gut-derived microbes play a key role in the preservation of internal anatomy and that differential preservation between exceptional deposits might be because of factors that control autolysis and microbial activity. The findings also suggest that the evolution of a through gut and its bacterial microflora increased the potential for exceptional fossil preservation in bilaterians, providing one explanation for the extreme rarity of internal preservation in those animals that lack a through gut.

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31

Adrain, Jonathan M., e Stephen R. Westrop. "Trilobite paleobiology: Past, present, and future". Journal of Paleontology 73, n. 2 (marzo 1999): 161–63. http://dx.doi.org/10.1017/s0022336000027682.

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Abstract (sommario):

The first major international trilobite conference (which also dealt with related arthropod groups) was convened by David Bruton in Oslo in 1973. That meeting resulted in a 467 page proceedings volume (Martinsson, 1975) that has become an indispensible reference on arthropod paleobiology. With its abundance of high-quality empirical work and influential ideas, the ongoing utility of “Fossils and Strata 4” is assured, yet it is also a fascinating microcosm of the themes and concerns of paleontology as a whole a quarter of a century ago. Paleoecology blossomed in the late 1960s and early 1970s. Autecology, and particularly functional morphology, dominates the volume, accounting for about one-third of the contributions. Plate tectonics was a relatively recent development in 1973 and, following the lead of Whittington and Hughes (1972), several papers tackled trilobite paleobiogeography. They vary from a bold attempt to determine oceanic circulation through the Ordovician by Ross to more conventional studies of biogeographic distribution that were aimed at providing further support for concepts of continental drift. There was a burgeoning interest in community paleoecology, and Richard Fortey's (1975) now-classic paper on the Early Ordovician faunas of Spitsbergen was the first to define trilobite “communities.” The volume was rounded out by diverse papers on trilobite anatomy based on material from the Burgess Shale and Beecher's Trilobite Bed, the microstructure of the trilobite cuticle, trilobites eyes, high level classification of trilobites, and various evolutionary themes (character displacement in agnostoids; adaptive radiation in Cambrian trilobites).

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32

Hou, Xianguang, Mark Williams, David J. Siveter, Derek J. Siveter, Richard J. Aldridge e Robert S. Sansom. "Soft-part anatomy of the Early Cambrian bivalved arthropods Kunyangella and Kunmingella : significance for the phylogenetic relationships of Bradoriida". Proceedings of the Royal Society B: Biological Sciences 277, n. 1689 (24 febbraio 2010): 1835–41. http://dx.doi.org/10.1098/rspb.2009.2194.

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33

MacDougall, Mark J., Anika Winge, Jasper Ponstein, Maren Jansen, Robert R. Reisz e Jörg Fröbisch. "New information on the early Permian lanthanosuchoid Feeserpeton oklahomensis based on computed tomography". PeerJ 7 (31 ottobre 2019): e7753. http://dx.doi.org/10.7717/peerj.7753.

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Abstract (sommario):

The cave deposits of the Lower Permian Richards Spur locality in Oklahoma, USA, have produced an incredible number of terrestrial tetrapod taxa, many of which are currently only known from this locality. One of the many recent taxa to be described from the locality was the small lanthanosuchoid parareptile Feeserpeton oklahomensis. Represented by a well-preserved, near complete skull, F. oklahomensis would have been a small predatory reptile, likely preying upon arthropods, and contributes to the extensive tetrapod fauna that was present at Richards Spur. New computed tomography data of the holotype and only specimen has allowed us to visualize and describe previously obscured and inaccessible anatomy of this taxon. These areas include the mandibular ramus, the palate, the sphenethmoid, the epipterygoids, and the braincase. Furthermore, this new anatomical information allowed formerly unknown character codings to be updated, thus we also performed new phylogenetic analyses that incorporated this new information. The results of these updated phylogenetic analyses are very similar to those of past studies, with F. oklahomensis being found as the sister taxon to all other lanthanosuchoids.

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34

Saunders, Katharine M., H. Jane Brockmann, Winsor H. Watson e Steven H. Jury. "Male horseshoe crabs Limulus polyphemus use multiple sensory cues to locate mates". Current Zoology 56, n. 5 (1 ottobre 2010): 485–98. http://dx.doi.org/10.1093/czoolo/56.5.485.

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Abstract (sommario):

Abstract The use of multisensory cues to locate mates can increase an organism's success by acting as a back-up plan when one system fails, by providing additional information to the receiver, and by increasing their ability to detect mates using senses that have different ranges in a variable aquatic environment. In this contribution we review the sensory cues that male horseshoe crabs Limulus polyphemus are known to use when locating mates and then provide new data that shed light on this subject. During the breeding season, females migrate into shore during high tides to spawn. Males attach to females as they approach the beach or are attracted to pairs already spawning. Vision is well established as an important cue in attracting males. Although chemoreception is well known in other marine arthropods, and horseshoe crabs have the anatomy available, there are few studies on chemical cues in this species. Experiments are presented here that provide evidence for chemical cue use. We show that the attraction, and retention, of attached and satellite males to actively spawning females and mating pairs involves multimodal cues.

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35

SHATROV, ANDREY B. "Comparative and functional morphology of the mouthparts in larvae of Parasitengona (Acariformes)*". Zoosymposia 6, n. 1 (20 dicembre 2011): 14–23. http://dx.doi.org/10.11646/zoosymposia.6.1.4.

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Abstract (sommario):

Anatomy and ultrastructural organization of the larval mouthparts in representatives of terrestrial (Trombiculidae parasitizing vertebrates and Microtrombidiidae parasitizing arthropods) as well as aquatic (Pionidae and Hydrodromidae parasitizing arthropods) families from the cohort Parasitengona were studied using whole-mount preparations, semi-thin sections and TEM and SEM methods. In these groups, the organization of the mouth apparatus differs significantly especially with regard to their particular functional specialization and adaptations reflecting evolutionary trends in these groups. In trombiculid larvae, the mouthparts reveal the simplest organization. The gnathosoma is totally free, the infracapitulum and the basal cheliceral segments are short and wide, and the latter are separated from each other. The flexible lateral lips form a temporary sucker, distinguishable when the larva feeds, and the pharynx is totally fused with the bottom of the infracapitulum. In microtrombidiid larvae, the gnathosoma is covered by the arched dorsal shield, the chelicerae are comparatively long and separated, and the lateral lips form a permanent sucker provided with an internal sclerite. Conversely, in water mite larvae, the chelicerae are fused together and either partially (Piona carnea) or totally (Hydrodroma despiciens) free from the overhanging idiosomal fold. The lateral lips are flexible and organized freely, and the pharynx is totally separated from the bottom of the infracapitulum. In general, water mite larvae show significant variations and specializations but at the same time seem to possess the most plesiomorphic characters in organization of the mouth apparatus. The ancestral parasitengone may have given rise to divergent groups of water mites as such, as well as to trombiculids with the secondary simplification of the mouth apparatus and to microtrombidiids with their particular additional adaptations and specialization in organization of the mouthparts.

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36

Serra, Armando Luís, e Ligiane Assis de Oliveira. "Anatomia comparada do aparelho bucal de espécies pertencentes à ordem díptera (Arthropoda, Insecta), com ênfase na morfologia funcional". ConScientiae Saúde 7, n. 1 (25 novembre 2008): 83–92. http://dx.doi.org/10.5585/conssaude.v7i1.1048.

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Abstract (sommario):

A diversidade das espécies da Ordem Díptera está correlacionada com a variação morfológica, que inclui a variação nas peças bucais, estruturas destinadas à alimentação, e no seu conjunto, forma o aparelho bucal, freqüentemente chamado de probóscide. As correlações entre adaptações morfológicas e hábitos alimentares são apresentadas por meio do estudo comparado das peças que compõem o aparelho bucal das famílias Bibionidae, Culicidae, Drosophilidae, Phoridae, Psychodidae, Shyrphidae e infraordem Muscomorpha. Os espécimes foram tratados com solução fervida de KOH 10%, seguida de uma série alcoólica para desidratação e fotografados com um fotomicroscópio. Os dados demonstram que as peças bucais sofrem variações, de acordo com o grupo analisado, tanto na estrutura quanto na função. O conhecimento das peças, de suas funções, do tamanho e da rigidez da probóscide possibilitam correlacionar as adaptações morfológicas com o hábito alimentar, além de encontrar algumas gradações entre a condição plesiomórfica e a apomórfica.

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37

Suslak, Thomas J., e Andrew P. Jarman. "Stretching the imagination beyond muscle spindles - stretch-sensitive mechanisms in arthropods". Journal of Anatomy 227, n. 2 (16 giugno 2015): 237–42. http://dx.doi.org/10.1111/joa.12329.

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38

H�rner, Michael. "Introduction to the cellular distribution of histamine and other biogenic amines in the nervous system of arthropods". Microscopy Research and Technique 44, n. 2-3 (15 gennaio 1999): 69. http://dx.doi.org/10.1002/(sici)1097-0029(19990115/01)44:2/3<69::aid-jemt1>3.0.co;2-s.

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39

Beutel, Rolf Georg, Xiao-Zhu Luo, Margarita I. Yavorskaya e Paweł Jałoszyński. "Structural megadiversity in leaf litter predators - the head anatomy of Pselaphus heisei (Pselaphinae, Staphylinidae, Coleoptera)". Arthropod Systematics & Phylogeny 79 (12 agosto 2021): 443–63. http://dx.doi.org/10.3897/asp.79.e68352.

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Abstract (sommario):

The head anatomy of Pselaphus heisei (Pselaphitae) is described and documented. The structural features are evaluated in comparison with findings presented in earlier studies on the subfamily, with a special focus on correlations with predacious habits and the groundplan of Pselaphinae. We found the tentorium, labrum, maxillary palps, shape of head, and a system of dorsal pits and sulci highly variable within the subfamily, reflecting multiple transformations, including many homoplasious changes. The following major characters are identified as groundplan features of Pselaphinae: falciform mandibles; small mola; semiglobular neck; ventrolateral antennal articulation; steep clypeal region; setiform labial palpomere 3; tentorium with nearly vertical main branches and lacking laminatentoria; separation of tentorial bridge from tentorial arms; fusion of dorsal tentorial arms with the head capsule; large brain placed in the posterior third of the head; and a triple cluster of well-developed cephalic glands. The last feature supports a hypothesis that multiple and independent cases of adaptations to myrmecophilous habits observed in various lineages of Pselaphinae were possible by re-programming already existing glands to produce appeasement secretions. The cephalic muscle apparatus of P. heisei is similar to what is found in other staphylinoid groups, with some exceptions, whereas it is strongly modified in the myrmecophile Claviger testaceus. We propose that the unparalleled structural megadiversity in Pselaphinae is primarily linked with life in the upper soil layers combined with specialized carnivorous habits, with small and agile or mechanically protected arthropods as prey. Within the group, various specialized life habits have evolved, including myrmecophily, termitophily, and also life in deep soil or caves, each with unique morphological adaptations.

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40

Pais-de-Azevedo, Tomás, Ramiro Magno, Isabel Duarte e Isabel Palmeirim. "Recent advances in understanding vertebrate segmentation". F1000Research 7 (23 gennaio 2018): 97. http://dx.doi.org/10.12688/f1000research.12369.1.

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Abstract (sommario):

Segmentation is the partitioning of the body axis into a series of repeating units or segments. This widespread body plan is found in annelids, arthropods, and chordates, showing it to be a successful developmental strategy for growing and generating diverse morphology and anatomy. Segmentation has been extensively studied over the years. Forty years ago, Cooke and Zeeman published the Clock and Wavefront model, creating a theoretical framework of how developing cells could acquire and keep temporal and spatial information in order to generate a segmented pattern. Twenty years later, in 1997, Palmeirim and co-workers found the first clock gene whose oscillatory expression pattern fitted within Cooke and Zeeman’s model. Currently, in 2017, new experimental techniques, such as new ex vivo experimental models, real-time imaging of gene expression, live single cell tracking, and simplified transgenics approaches, are revealing some of the fine details of the molecular processes underlying the inner workings of the segmentation mechanisms, bringing new insights into this fundamental process. Here we review and discuss new emerging views that further our understanding of the vertebrate segmentation clock, with a particular emphasis on recent publications that challenge and/or complement the currently accepted Clock and Wavefront model.

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41

Ortuño, V. M., e P. Barranco. "Duvalius (Duvalius) lencinai Mateu & Ortuño, 2006 (Coleoptera, Carabidae, Trechini) una especie hipogea del sur de la península ibérica. Morfología, reubicación taxonómica, sistemática y biología". Animal Biodiversity and Conservation 36, n. 2 (dicembre 2013): 141–52. http://dx.doi.org/10.32800/abc.2013.36.0141.

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Abstract (sommario):

Duvalius (Duvalius) lencinai Mateu & Ortuño, 2006 (Coleoptera, Carabidae, Trechini) a hypogean species from the south of the Iberian peninsula. Morphology, new taxonomic placement, systematics and biology Duvalius (Duvalius) lencinai Mateu & Ortuño, 2006 was discovered in two new localities in the municipal district of Siles (Jaen, Spain): Sima Curva del Espino and Sima de los 30 Años, approximately 10 and 17 km, respectively, away from the type locality. The study of several individuals through dissection and use of optic and electronic microscopic preparations has increased the knowledge of the anatomy of this species. Evagination of the internal sac allowed further study of the sclerotized structures and led to the proposal of a new placement for this species within the genus Trechus Clairville 1806: Trechus (Trechus) lencinai (Mateu & Ortuño, 2006) n. comb. Although it comprises characters of the T. fulvus group and the T. pyrenaeus group, the endophallus is more similar to several species of the T. quadristriatus group and the T. tingitanus group. It could not therefore be placed in any of the species groups proposed by Jeannel. Some data about its biology (temporal and spatial distribution) and accompanying arthropod fauna are given.

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42

Qvarnström, Martin, Erik Elgh, Krzysztof Owocki, Per E. Ahlberg e Grzegorz Niedźwiedzki. "Filter feeding in Late Jurassic pterosaurs supported by coprolite contents". PeerJ 7 (26 agosto 2019): e7375. http://dx.doi.org/10.7717/peerj.7375.

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Abstract (sommario):

Diets of pterosaurs have mainly been inferred from indirect evidence such as comparative anatomy, associations of co-occurring fossils, and functional morphology. Gut contents are rare, and until now there is only a single coprolite (fossil dropping), with unidentified inclusions, known. Here we describe three coprolites collected from a palaeosurface with numerous pterosaur tracks found in early Kimmeridgian (Hypselocyclum Zone) intertidal deposits of the Wierzbica Quarry, Poland. The specimens’ morphology and association to the tracks suggest a pterosaur producer. Synchrotron scans reveal numerous small inclusions, with foraminifera making up the majority of the identifiable ones. Other small remains include shells/carapaces (of bivalves, ostracods, and other crustaceans/arthropods) and bristles (some possibly of polychaete worms). The high density of the small shelly inclusions suggest that they were not accidently ingested, but constituted an important food source for the pterosaur(s), perhaps together with unpreserved soft-bodied animals. The combined evidence from the tracks and coprolites suggest a filter-feeding ctenochasmatid as the most likely tracemaker. If true, this significantly expands the bromalite record for this pterosaur group, which was previously only known from gastroliths. Moreover, this study also provides the first direct evidence of filter feeding in Jurassic pterosaurs and shows that they had a similar diet to the recent Chilean flamingo (Phoenicopterus chilensis).

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43

Qvarnström, Martin, Joel Vikberg Wernström, Rafał Piechowski, Mateusz Tałanda, Per E. Ahlberg e Grzegorz Niedźwiedzki. "Beetle-bearing coprolites possibly reveal the diet of a Late Triassic dinosauriform". Royal Society Open Science 6, n. 3 (marzo 2019): 181042. http://dx.doi.org/10.1098/rsos.181042.

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Abstract (sommario):

Diets of extinct animals can be difficult to analyse if no direct evidence, such as gut contents, is preserved in association with body fossils. Inclusions from coprolites (fossil faeces), however, may also reflect the diet of the host animal and become especially informative if the coprolite producer link can be established. Here we describe, based on propagation phase-contrast synchrotron microtomography (PPC-SRμCT), the contents of five morphologically similar coprolites collected from two fossil-bearing intervals from the highly fossiliferous Upper Triassic locality at Krasiejów in Silesia, Poland. Beetle remains, mostly elytra, and unidentified exoskeleton fragments of arthropods are the most conspicuous inclusions found in the coprolites. The abundance of these inclusions suggests that the coprolite producer deliberately targeted beetles and similar small terrestrial invertebrates as prey, but the relatively large size of the coprolites shows that it was not itself a small animal. The best candidate from the body fossil record of the locality is the dinosauriform Silesaurus opolensis Dzik, 2003, which had an anatomy in several ways similar to those of bird-like neotheropod dinosaurs and modern birds. We hypothesize that the beak-like jaws of S. opolensis were used to efficiently peck small insects off the ground, a feeding behaviour analogous to some extant birds.

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44

Robin, N., P. Gueriau, J. Luque, D. Jarvis, A. C. Daley e R. Vonk. "The oldest peracarid crustacean reveals a Late Devonian freshwater colonization by isopod relatives". Biology Letters 17, n. 6 (giugno 2021): 20210226. http://dx.doi.org/10.1098/rsbl.2021.0226.

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Abstract (sommario):

Peracarida (e.g. woodlice and side-swimmers) are, together with their sister-group Eucarida (e.g. krill and decapods), the most speciose group of modern crustaceans, suggested to have appeared as early as the Ordovician. While eucarids' incursion onto land consists of mainly freshwater and littoral grounds, some peracarids have evolved fully terrestrial ground-crawling ecologies, inhabiting even our gardens in temperate regions (e.g. pillbugs and sowbugs). Their fossil record extends back to the Carboniferous and consists mainly of marine occurrences. Here, we provide a complete re-analysis of a fossil arthropod— Oxyuropoda— reported in 1908 from the Late Devonian floodplains of Ireland, and left with unresolved systematic affinities despite a century of attempts at identification. Known from a single specimen preserved in two dimensions, we analysed its anatomy using digital microscopy and multispectral macroimaging to enhance the contrast of morphological structures. The new anatomical characters and completeness of Oxyuropoda , together with a phylogenetic analysis with representatives of all major Eumalacostraca groups, indicate that Oxyuropoda is a crown peracarid, part of a clade including amphipods and isopods. As such, Oxyuropoda is the oldest known species Peracarida, and provides evidence that derived peracarids had an incursion into freshwater and terrestrial environments as early as the Famennian, more than 360 Ma.

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45

Gopfert, M. C., H. Briegel e D. Robert. "Mosquito hearing: sound-induced antennal vibrations in male and female Aedes aegypti". Journal of Experimental Biology 202, n. 20 (15 ottobre 1999): 2727–38. http://dx.doi.org/10.1242/jeb.202.20.2727.

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Abstract (sommario):

Male mosquitoes are attracted by the flight sounds of conspecific females. In males only, the antennal flagellum bears a large number of long hairs and is therefore said to be plumose. As early as 1855, it was proposed that this remarkable antennal anatomy served as a sound-receiving structure. In the present study, the sound-induced vibrations of the antennal flagellum in male and female Aedes aegypti were compared, and the functional significance of the flagellar hairs for audition was examined. In both males and females, the antennae are resonantly tuned mechanical systems that move as simple forced damped harmonic oscillators when acoustically stimulated. The best frequency of the female antenna is around 230 Hz; that of the male is around 380 Hz, which corresponds approximately to the fundamental frequency of female flight sounds. The antennal hairs of males are resonantly tuned to frequencies between approximately 2600 and 3100 Hz and are therefore stiffly coupled to, and move together with, the flagellar shaft when stimulated at biologically relevant frequencies around 380 Hz. Because of this stiff coupling, forces acting on the hairs can be transmitted to the shaft and thus to the auditory sensory organ at the base of the flagellum, a process that is proposed to improve acoustic sensitivity. Indeed, the mechanical sensitivity of the male antenna not only exceeds the sensitivity of the female antenna but also those of all other arthropod movement receivers studied so far.

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Patek, Sheila N. "Squeaking with a sliding joint: mechanics and motor control of sound production in palinurid lobsters". Journal of Experimental Biology 205, n. 16 (15 agosto 2002): 2375–85. http://dx.doi.org/10.1242/jeb.205.16.2375.

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Abstract (sommario):

SUMMARY The origin of arthropod sound-producing morphology typically involves modification of two translating body surfaces, such as the legs and thorax. In an unusual structural rearrangement, I show that one lineage of palinurid lobsters lost an antennal joint articulation, which transformed this joint from moving with one degree of freedom into a sliding joint with multiple degrees of freedom. With this sliding joint, `stick-and-slip' sounds are produced by rubbing the base of each antenna against the antennular plate. To understand the musculo-skeletal changes that occurred during the origin and evolutionary variation of this sound-producing mechanism, I examined joint morphology and antennal muscle anatomy across sound-producing and non-sound-producing palinurids. Plectrum movement and antennal muscle activity were measured in a sound-producing species, Panulirus argus. The promotor muscle pulls the plectrum over the file during sound-producing and non-sound-producing movements; a higher intensity of muscle activity is associated with sound production. The promotor muscle is larger and attaches more medially in sound-producing palinurids than in non-sound producers. In Panulirus argus, each shingle on the file has an additional ridge; in Palinurus elephas, the shingle surfaces are smooth. These differences in shingle surface features suggest variation in the stick-and-slip properties of the system. Translational motion permitted by the sliding joint is necessary for sound production; hence, the construction of a sliding joint is a key modification in the origin of this sound-producing mechanism.

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47

Aria, Cédric, e Jean-Bernard Caron. "Cephalic and Limb Anatomy of a New Isoxyid from the Burgess Shale and the Role of “Stem Bivalved Arthropods” in the Disparity of the Frontalmost Appendage". PLOS ONE 10, n. 6 (3 giugno 2015): e0124979. http://dx.doi.org/10.1371/journal.pone.0124979.

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48

Rico-Guevara, Alejandro. "Relating form to function in the hummingbird feeding apparatus". PeerJ 5 (8 giugno 2017): e3449. http://dx.doi.org/10.7717/peerj.3449.

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Abstract (sommario):

A complete understanding of the feeding structures is fundamental in order to study how animals survive. Some birds use long and protrusible tongues as the main tool to collect their central caloric source (e.g., woodpeckers and nectarivores). Hummingbirds are the oldest and most diverse clade of nectarivorous vertebrates, being a perfect subject to study tongue specializations. Their tongue functions to intraorally transport arthropods through their long bills and enables them to exploit the nectarivorous niche by collecting small amounts of liquid, therefore it is of vital importance to study its anatomy and structure at various scales. I focused on the portions of the hummingbird tongue that have been shown to be key for understanding their feeding mechanisms. I used histology, transmission and scanning electron microscopy, microCT, andex-vivoexperiments in order to advance the comprehension of the morphology and functioning of the hummingbird feeding apparatus. I found that hummingbird tongues are composed mainly of thin cornified epithelium, lack papillae, and completely fill the internal cast of the rostral oropharyngeal cavity. Understanding this puzzle-piece match between bill and tongue will be essential for the study of intraoral transport of nectar. Likewise, I found that the structural composition and tissue architecture of the tongue groove walls provide the rostral portion of the tongue with elastic properties that are central to the study of tongue-nectar interactions during the feeding process. Detailed studies on hummingbirds set the basis for comparisons with other nectar-feeding birds and contribute to comprehend the natural solutions to collecting liquids in the most efficient way possible.

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49

Coatham, Samuel J., Jakob Vinther, Emily J. Rayfield e Christian Klug. "Was the Devonian placoderm Titanichthys a suspension feeder?" Royal Society Open Science 7, n. 5 (maggio 2020): 200272. http://dx.doi.org/10.1098/rsos.200272.

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Abstract (sommario):

Large nektonic suspension feeders have evolved multiple times. The apparent trend among apex predators for some evolving into feeding on small zooplankton is of interest for understanding the associated shifts in anatomy and behaviour, while the spatial and temporal distribution gives clues to an inherent relationship with ocean primary productivity and how past and future perturbations to these may impact on the different tiers of the food web. The evolution of large nektonic suspension feeders—‘gentle giants’—occurred four times among chondrichthyan fishes (e.g. whale sharks, basking sharks and manta rays), as well as in baleen whales (mysticetes), the Mesozoic pachycormid fishes and at least twice in radiodontan stem group arthropods (Anomalocaridids) during the Cambrian explosion. The Late Devonian placoderm Titanichthys has tentatively been considered to have been a megaplanktivore, primarily due to its gigantic size and narrow, edentulous jaws while no suspension-feeding apparatus have ever been reported. Here, the potential for microphagy and other feeding behaviours in Titanichthys is assessed via a comparative study of jaw mechanics in Titanichthys and other placoderms with presumably differing feeding habits (macrophagy and durophagy). Finite-element models of the lower jaws of Titanichthys termieri in comparison to Dunkleosteus terrelli and Tafilalichthys lavocati reveal considerably less resistance to von Mises stress in this taxon. Comparisons with a selection of large-bodied extant taxa of similar ecological diversity reveal similar disparities in jaw stress resistance. Our results, therefore, conform to the hypothesis that Titanichthys was a suspension feeder with jaws ill-suited for biting and crushing but well suited for gaping ram feeding.

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Labonte, David, Christofer J. Clemente, Alex Dittrich, Chi-Yun Kuo, Alfred J. Crosby, Duncan J. Irschick e Walter Federle. "Extreme positive allometry of animal adhesive pads and the size limits of adhesion-based climbing". Proceedings of the National Academy of Sciences 113, n. 5 (19 gennaio 2016): 1297–302. http://dx.doi.org/10.1073/pnas.1519459113.

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Organismal functions are size-dependent whenever body surfaces supply body volumes. Larger organisms can develop strongly folded internal surfaces for enhanced diffusion, but in many cases areas cannot be folded so that their enlargement is constrained by anatomy, presenting a problem for larger animals. Here, we study the allometry of adhesive pad area in 225 climbing animal species, covering more than seven orders of magnitude in weight. Across all taxa, adhesive pad area showed extreme positive allometry and scaled with weight, implying a 200-fold increase of relative pad area from mites to geckos. However, allometric scaling coefficients for pad area systematically decreased with taxonomic level and were close to isometry when evolutionary history was accounted for, indicating that the substantial anatomical changes required to achieve this increase in relative pad area are limited by phylogenetic constraints. Using a comparative phylogenetic approach, we found that the departure from isometry is almost exclusively caused by large differences in size-corrected pad area between arthropods and vertebrates. To mitigate the expected decrease of weight-specific adhesion within closely related taxa where pad area scaled close to isometry, data for several taxa suggest that the pads’ adhesive strength increased for larger animals. The combination of adjustments in relative pad area for distantly related taxa and changes in adhesive strength for closely related groups helps explain how climbing with adhesive pads has evolved in animals varying over seven orders of magnitude in body weight. Our results illustrate the size limits of adhesion-based climbing, with profound implications for large-scale bio-inspired adhesives.

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