Subphylum Vertebrata Phylum Chordata Fishes Subphylum Vertebrata Phylum Chordata

Classes Superclass Agnatha (jawless) Class Myxini Class Petromyzontida Superclass Gnathostomata (have jaws) Class Chondrichthyes Class Actinopterygii Class Sarcopterygii

Class Myxini Hagfishes Scavengers Feed on Annelids, Molluscs, crustaceans and dead or dying fish Very developed senses of smell and touch Almost completely blind No paired appendages Biting mouth has two rows of eversible (to turn inside out) teeth, but no jaws

Class Petromyzontida Lampreys Free living or parasitic Reproduce in winter or spring in streams Males build nest Female uses mouth to hold onto stone to position over nest releasing eggs As eggs are shed into nest, they are fertilized by male Adults will die soon after 2 dorsal fins, no paired appendages Cartilaginous skeleton

Class Chondrichthyes Cartilaginous skeleton 2 subclasses: No bone is present, even though their derived ancestors have well developed bone It was believed to have been lost through a process called neoteny – phosphatized mineral tissues were retained in teeth, scales and spines 2 subclasses: Elasmobranchii Holocephali

Subclass Elasmobranchii Sharks, Skates, Rays Although most sharks are timid, they can be very dangerous to humans Great white shark, mako shark, tiger shark, bull shark and the hammerhead sharks Dorsal (top) and Caudal (tail) fins provide thrust and some lift as it sweeps back and forth They have paired pectoral and pelvic fins (side fins) Have upper and lower jaws filled with sharp teeth

Sharks and their prey Can detect prey from a kilometer or more away, using their olfactory senses Prey can also be located by sensing low-frequency vibrations As the prey gets closer, sharks will switch to vision Contrary to popular belief, sharks have excellent vision Use their electroreceptor's to detect prey in the final moments of the attack.

Subclass Holocephali Ratfish, spookfish, ghostfish, Chimaeras Today only 33 species exists Upper jaw is completely fused to cranium Food consists of seaweed, molluscs, echinoderms, crustaceans and fishes

Class Actinopterygii Ray-finned fishes Boney fish Single dorsal fin Earliest evidence of this class indicates a heterocercal caudal fin (similar to those of a shark) 3 subclasses Cladistia Chondrostei Neopterygii

Types of caudal tails

Subclass Cladistia Bichirs have lungs heavy ganoid scales most ancient

Subclass Chondrosteans Sturgeons and paddle fish Recently, populations have declined due to dam construction, overfishing and pollution Sturgeon Paddlefish

Subclass Neopterygians Bowfin and Gars Led to the modern boney fish, teleosts Needle-like teeth Gulp surface air Filling their swim bladder with air to supplement oxygen obtained in the gills Gar Bowfin

Teleosts 27,000 species described – great diversity Represent 96% of all living fishes or about half of all vertebrates Eels, catfishes – completely lost gills Other species have gills that are thin, light and flexible Increase speed and motility Have a homocercal caudal fin permits greater speed Dorsal fin is now flexible and can have specialized function Adaptations to jaws Sliding of upper jaw to increase final attack velocity Act as a suction device Chewing, grinding and crushing

Eels Giant Catfish- 646 pounds Normal Catfish

Class Sarcopterygii Rhipidistians, lung fishes, coelacanths Early ancestors had lungs as well as gills, and heterocercal tails However, now has evolved to have a diphycercal tail Powerful jaws Heavy enameled scales Lungfish- some lungfishes can live out of water for periods of time In order to survive dry periods, the lungfish may create a slime mixed with mud to form a cocoon Lungfish