摘要:

Functional and structural patterns in the pharyngeal jaw apparatus of euteleostean fishes are described and analysed as a case study of the transformation of a complex biological design. The sequential acquisition of structural novelties in the pharyngeal apparatus is considered in relation to both current hypotheses of euteleostean phylogeny and patterns of pharyngeal jaw function. Several euteleostean clades are corroborated as being monophyletic, and morphologically conservative features of the pharyngeal jaw apparatus are recognized.Functional analysis, using cinematography and electromyography, reveals four distinct patterns of muscle activity during feeding in primitive euteleosts (Esox) and in derived euteleostean fishes(Perca, Micropterus, Ambloplites, Pomoxis). The initial strike, buccal manipulation, pharyngeal manipulation, and the pharyngeal transport of prey into the oesophagus all involve unique muscle activity patterns that must be distinguished in analyses of pharyngeal jaw function. During pharyngeal transport, the upper and lower pharyngeal jaws are simultaneously protracted and retracted by the action of dorsal and ventral musculoskeletal gill arch couplings. The levator externus four and retractor dorsalis muscles, anatomical antagonists, overlap for 70–90°of their activity period. Levatores externi one and two are the main protractors of the upper pharyngeal jaws in the acanthopterygian fishes studied. The major features of pharyngeal jaw movement in primitive euteleosts are retained in many derived clades in spite of a dramatic structural reorganization of the pharyngeal region. Homologous muscles have radically changed their relative activity periods while pharyngeal jaw kinematics have been modified relatively little.Patterns of transformation of activity may thus bear little direct relationship to the sequence of structural modification in the evolution of complex designs. Overall function of a structural system may be maintained, however, through co‐ordinated modifications of the timing of muscle activity and anatomical reorientation of the musculoskeletal system. Deeper understanding of the principles underlying the origin and transformation of functional design in vertebrates awaits further information on the acquisition of both structural and functional novelties at successive hierarchical levels within monophyietic clades. This is suggested as a key goal of future research in functional and evolutionary morpho

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1983.tb01719.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The six species of Widow‐spiders (Latrodectus) found in Israel are revised. Three of them are reported for the first time from this region. The MediterraneanL.tredecimguttatusis maintained as a distinct species differing from the AmericanL.mactans, while evidence on the occurrence in Israel of a distinct population, close to the AmericanL.hesperusis provided. Five sympatric species ofLatrodectusare found in the more arid zones of Israel and one allopatric population of the cosmotropicalL.geometricusoccurs in the Mediterranean Coastal Plain. A conspectus on the systematics alongside distribution and ecological records of each species is given. The biological and morphological distinctive characters separating the species are then assessed in an extended discussion. Illustrations and a key to the species are provide

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1983.tb01720.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Twenty‐two specimens of pycnogonid representing nine species arc recorded from deep waters around the British Isles. The samples are from the Faroe Channel, the Hebridean Terrace and the vicinity of the Great Sole Bank, taken at depths of between 200 and 1835 m. These specimens demonstrate marked southern range extensions forAymphon teptochelesandPallenopsis tritonis, and include the northernmost record for the genusCilunculus(C. alcicornis) and the third European record forColossendeis arcuata. Protonymphon larvae ofN. leptochelesandParanymphon spinosumare figure

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1983.tb01721.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The morphology and mechanics of feeding inDermophis mexicanuswere studied using descriptive anatomical, cinematographic and electromyographic approaches. The lower jaw has a retroarticular process extending one‐third of the total jaw length, and an articulation that restricts anteroposterior movements. Muscles from three anatomically distinct sites, the temporal fossa, the lateral surface of the neck, and the subvertebral region, act to execute the bite during feeding on earthworms. Muscles in the first of these sites are comparable to the jaw adductors of other vertebrates, while those in the second two represent morphological and functional departures. The large interhyoideus muscle and the elongate retroarticular process are modified to function in jaw closing. The longus capitis muscles appear to act to depress the cranium at the cranio‐vertebral joint, a motion that occurs simultaneously with maximum jaw closing. The latter two muscles appear to have greater importance for feeding inDermophisthan do the temporal adductors, and the evolution of this specialized arrangement may be related to the demands for a reduced cross‐sectional area of the head in these burrowing verteb

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1983.tb01722.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1983.tb01722a.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1983.tb01719a.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY