Cartilaginous fishes Class Chondrichthyes

Marine Fishes Class Chondrichthyes – Cartilaginous fishes; with about 1000 different species, they include the different species of sharks, rays, skates, and ratfish. Cartilaginous fishes have well developed jaws and teeth; Typically have a ventral mouth; and, have rough, sandpaper-like skin because of tiny scales… In fact, their teeth are simply modified scales!!

Marine Fishes – Sensory System Marine fishes have well developed nervous and sensory systems. Many have a great sense of smell. Their nostrils open to olfactory sacs on both sides of the head. Some sharks can detect blood at concentrations as little as one part per million! Fishes detect taste with their taste buds in their mouth, as well as on their barbels (whisker-like organs found around the mouths of some bottom dwelling fishes). Most fish have a somewhat well developed sense of vision. Some shallow water bony fishes have color vision, but most fishes do not… also, focusing is done by moving the lens as supposed to changing it’s shape… Some cartilaginous fish have sensory organs around the head called ampullae of Lorenzini. They can detect week electrical fields that may be used for navigation, as well as for detecting prey. Most fishes can also perceive sounds with their inner ear, and they can detect changes in their position within the water column using their ear stones or otoliths… (nerve cells detect changes in positioning).

Senses

Senses

Barbels – Atlantic Sturgeon

Marine Fishes – Sensory System (cont.) Finally, many fish have a lateral line that allows them to sense vibrations in the water…

types of caudal fin : (A) - Heterocercal, (B) - Protocercal, (C) - Homocercal, (D) - Diphycercal

Shark Diet Discovery Channel Videos: The Ultimate Guide to Sharks: Shark Diet Air Jaws: Sharks of South Africa: Shark Feeding Frenzy Air Jaws: Sharks of South Africa: Filming Air Jaws

Shark Mating Discovery Channel Videos: The Ultimate Guide to Sharks: Shark Mating The Ultimate Guide to Sharks: Shark Birth and Maturation Sibling cannibalism

Skates vs. Rays Different Orders Reproduction Tooth Structure Rays are viviparous (live bearing) while skates are oviparous (egg laying), releasing their eggs in rectangular cases sometimes called "mermaid´s purses". Tooth Structure Although skates may have small teeth, those of rays are plate-like and adapted for crushing prey.  Morphology Skates normally have prominent dorsal fins while those of rays are absent or reduced in rays. Although a few electric rays are capable of delivering a powerful electric shock and some sting rays have large, barbed stingers, in general, these docile animals pose no real threat to swimmers and divers.

Skate