摘要:

Colour patterns, shape and behaviour are analysed in 22 species of aphidophagous syrphid larvae in relation to their possible role in defence against visually hunting predators. Crypsis is the most important method of primary defence. There is much variation in colour pattern. Some species are translucent, others green, brown or otherwise coloured. Most have disruptive stripes, bars or other markings that break up the body outline at short range. There is one example of a bird dropping resemblance. Behavioural requirements for effective crypsis include diurnal immobility, resting in sites that provide maximum concealment, and slow interrupted locomotion. Secondary defences are less variable and involve catalepsis, attack with saliva, and rolling and dropping from the plant.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01188.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Fishes are generally believed to differ in their ability to alter (modulate) their feeding behaviour in response to different prey. We investigated modulation quantitatively in four species of sunfishes (Centrarchidae) by evaluating the variation in 11 electromyographic variables measured from recordings of electrical activity in head muscles during feeding on three prey types. The experimental design used allowed us to partition variation between species, among individuals within species, among prey types, and among feedings. Duration of activity of the sternohyoideus muscle was the only variable significantly different among the four species. All variables showed significant differences among individuals within species. The overall range of activity of each muscle activity variable was about the same for all four sunfishes. However, three species showed a significant ability to modulate most muscle variables while a fourth did not change its feeding response with respect to prey type. The results indicate that: (1) intraspecific variation is an important source of variability in functional attributes that should be accounted for in comparisons between species; (2) the ability of some species to modulate appears to be independent of the potential variability in muscle activity possessed by each species; (3) closely related species can differ considerably in their ability to alter muscle electrical activity patterns during feeding; and (4) a quantitative assessment of variation in electromyographic patterns is a powerful approach for asking questions about differences in feeding behaviour.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01189.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Recent sampling in the Rockall Trough, Porcupine Seabight and Porcupine Abyssal Plain, in the NE Atlantic, has yielded 200 specimens of apodous holothurians belonging to seven species of the family Myriotrochidae Théel from depths between 1000 and 4310 m. These include the type species of a new genus and two new species of existing genera.Parvotrochus belyaevigen. et sp. nov. is described from some minute specimens from the Rockall Trough that possess both exceptionally small wheel‐like deposits and numerous, large curved rods in the body wall and tentacles.Myriotrochus clarkisp. Nov. has affinities toM. vitreus(M. Sars) but shows differences in the shape of the plates of the calcareous ring and in having larger, frequently abnormally formed, wheels.Siniotrochus myriodontussp. Nov. is similar to the type species of this genus,S. phoxus, Pawson, but differs in the arrangement of the teeth on the wheels. A single small specimen ofPrototrochusBelyaev et Mironov from the Whittard Canyon, northern Bay of Biscay, is similar toP. minutus(Östergren), a species known only from the Sea of Japan, but differs in some characteristics of the wheels and tentacles. A new subspecies,P. zenkevitchi rockallensissubsp. nov., is proposed for a form ofP. zenkevitchi(Belyaev) that was the most common myriotrochid encountered.P. zenkevitchiwas known previously only from a few localities in the Pacific and S Atlantic deep‐sea trenches. Similarly, two species previously known only from the NE Pacific,Myriotrochus bathybiusH. L. Clark andM. giganteusH. L. Clark, are also recorded from the N Atlantic for the first time. The synonymy ofM. giganteusandM.sp. ex gr.macquariensis‐giganteusBelyaev et Mironov is proposed.The greatest number both of specimens and species came from the areas most intensively sampled. The present records show that several species have world‐wide distributions. The wide geographic separation of many records is the result of both poor sampling effort in the deep sea, particularly with fine‐meshed gear, and the difficulties in sampling infaunal animals in the deep sea. Box core samples in the Rockall Trough suggest that the myriotrochids are more common in this area than would be supposed from epibenthic sledge data. Hence, myriotrochids may be more prevalent in the deep sea than previou

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01190.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

There are two basic designs of the aquatic feeding mechanism in lower vertebrates: unidirectional and bidirectional flow systems. Larval salamanders and most fishes posses a unidirectional flow design in which water drawn into the mouth with the prey passes over the gills and exits posteriorly. Metamorphosed salamanders and all other aquatic vertebrates possess a bidirectional system in which water flows into and out of the mouth during a single feeding cycle. We investigated the functional consequences of these two feeding designs in larval and metamorphosed tiger salamanders (Ambystoma tigrinum) feeding in the water. Buccal cavity pressures were measured during feeding and 11 variables measured from the pressure traces. Significant differences were found between the larval and metamorphosed salamanders in eight variables. Larval salamanders generate significantly greater negative pressures than do metamorphosed individuals and a principal components analysis of the 11 pressure variables completely separates larval from metamorphosed salamanders. Larval individuals are significantly better at capturing elusive prey than are metamorphosed salamanders, apparently because of changes in the structure of the feeding mechanism and the concomitant functional modifications.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01191.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY