Cartilaginous fishesClass 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 welldeveloped jaws and teeth;

Typically have a ventral mouth;

and, have rough, sandpaper-likeskin because of tiny scales…In fact, their teeth are simply modified scales!!

Marine Fishes – Sensory SystemMarine fishes have well developed nervous and sensory systems.

Many have a great sense of smell. Their nostrils open to olfactorysacs on both sides of the head. Some sharks can detectblood at concentrations as little as one part per million!

Fishes detect taste with their taste buds in their mouth, as well ason 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 fishesdo not… also, focusing is done by moving the lens as supposedto changing it’s shape…

Some cartilaginous fish have sensory organs around the head calledampullae of Lorenzini. They can detect week electrical fieldsthat may be used for navigation, as well as for detecting prey.

Most fishes can also perceive sounds with their inner ear, and they can detectchanges in their position within the water column using their earstones 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 Feedin

g Frenzy• Air Jaws: Sharks of South Africa: Filming Air J

aws

Shark Mating

• Discovery Channel Videos:• The Ultimate Guide to Sharks: Shark Mating• The Ultimate Guide to Sharks: Shark Birth an

d Maturation• Sibling cannibalism

Skates vs. Rays• Different Orders• Reproduction

– 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