the mouths of some bony and cartilaginous fishes are located in the anterior part of theirbodies, with a slight variation in sharks, which have theirs located in the abdominal part. thisvariation is evolutionary over time. the force exerted by the jaws of sharks in order todismember their prey can be examined from two origins: .the determined force exerted by teethand muscles and the force as a...

This study investigated the pattern of the electrical field potentials recorded near the prebranchial chamber of the native crayfish Astacus leptodactylus. Inside the prebranchial chamber, the electrical waves had maximal amplitude and showed 2-4 peaks per cycle. Potentials with the same frequency but smaller amplitude and simpler shape were also recorded outside the chamber, near the edge of t...

The external morphology and axial skeleton of 5 species Antarctic plunderfishes the genus Artedidraco Lönnberg, 1905 were studied using materials from collection ZIN. Plastic (26) meristic (14) characters analyzed; a morphological characteristics was prepared. results study partially con firm previously revealed differences between genus, but some diagnostic are found for first time: number bra...

Pressure measurements made at various points inside the mantle show that the ventilatory stream of the resting animal is driven by very small (often less than 0 5 cmH20) pressure differences. Inspiration occupies less than onethird of the total cycle time, while flow across the gills is evidently continuous, since there is always a pressure differential between the prebranchial and postbranchia...

The mouths of some bony and cartilaginous fishes are located in the anterior part of theirbodies, with a slight variation in sharks, which have theirs located in the abdominal part. Thisvariation is evolutionary over time. The force exerted by the jaws of sharks in order todismember their prey can be examined from two origins: .The determined force exerted by teethand muscles and the force as a...

Holthuisana valentula Riek and H. agassizi (Rathbun) both ventilate their lungs by lateral oscillations of the thoracic walls within the branchial chambers. Air enters and leaves the lungs via the prebranchial apertures and the Milne-Edwards apertures. At rest, active ventilation in H. transversa was low (0-95 mlg~^ h") and a high diffusional component was evident. After disturbance, VA rose to...

The aim of this study was to analyze the taxonomy and distribution of the polychaetes of the family Paraonidae from a lagoon-estuarine ecosystem in the Gulf of Mexico. The samples come from 20 soft bottom stations in the Términos Lagoon during the dry and rainy seasons, of which eight included paraonids. In all, 1183 specimens belonging to two new species were identified: Aricidea (Acmira) hirs...