Class Chondrichthyes aka Cartilaginous fishes sharks and rays sharks and rays

General Characteristics These organisms have a skeleton made of cartilage These organisms have movable jaws with lots of teeth Mouth is almost always located under the head Mouth is almost always located under the head These organisms have paired lateral fins Skin is covered in placoid scales Sand paper like material that are made of the same material as the teeth Sand paper like material that are made of the same material as the teeth

Placoid Scales

Sharks Adapted for fast swimming and some are the top predators in the sea Very few have evolved from their original forms They have a well developed caudal fin Typically have paired dorsal and pectoral fins They have 5 to 7 gill slits on each side of the body Often have rows of powerful teeth and constantly replace teeth as they lose them

Sharks cont. Found mostly in tropical waters at almost all depths Fished for their meat, oil and skin which is used like leather Shark fins are used in the Orient for medicinal soups Over fishing of sharks has damaged the populations so restrictions are beginning to apply

Sharks cont. Hammerhead Shark Flattened heads Flattened heads Eyes and nostrils at the tips of the flat head Eyes and nostrils at the tips of the flat head Head is used as a rudder Head is used as a rudder Space between eyes and nostrils improves sensory abilities Space between eyes and nostrils improves sensory abilities

Sharks cont. Whale Shark Largest fish Largest fish Found in tropical waters Found in tropical waters Can be 60 ft long Can be 60 ft long All are filter feeders All are filter feeders

Rays and Skates Almost all have flattened bodies and are bottom dwellers The most identifiable characteristic are the ventrally located gill slits The pectoral fins are greatly expanded and resemble wings

Stingray Most common type of ray off our beaches Have a whip like tail with a barb at the base The barb has a poison gland Often cover themselves with sand Feed on clams, crabs and other small fishes Teeth are modified into grinding plates to crush their prey

Electric Ray Have specialized cells on each side of the body that produce electricity Stun fish to eat Ancient peoples used to use the shock to cure illnesses

Rat Fish Have only one pair of gill slits Some have a long rat-like tail Feed on crustaceans and mollusks