Phylum Chordata

Subphylum Vertebrata

Superclass Agnatha

Class Myxini

Class Cephalaspidomorphi

Superclass Gnathostomata

Class Chondrichthyes

Subclass Elasmobranchii

Subclass Holocephali

Class Osteichthyes

Subclass Actinopterygii

Subclass Sarcopterygii

Class Amphibia

Class Reptilia

Class Aves

Class Mammalia

Superclass Agnatha

Class Myxini - hagfishes

reduced eyes

slime

notochord persistent -

pore-like gill openings

Internal fluids are isosmotic with sea water

pronephric kidneys anteriorly and mesonephric kidneys posteriorly

Class Cephalaspidomorphi - lampreys

anadromous

larvae = ammocoetes

Opisthonephric kidney

Digestive system without stomach -

Class Chondrichthyes

cartilaginous skeleton

Subclass Elasmobranchii - sharks, skates, and rays

fusiform body (spindle shaped)

Heterocercal tail

Pectoral and pelvic fins, two dorsal fins, a caudal fin, an anal fin.

Spiracle = remnant of 1^st gill slit

Placoid scales

Lateral line system and Ampulla of Lorenzini

Spiral valve in intestine

Opisthonephric kidneys aided by rectal gland

Two chambered heart = ventricle and atrium

Internal fertilization Males have claspers on anal fin

Osmoregulate by retaining urea in the blood

Subclass Holocephali - ratfishes or chimaeras

Bony plates inside jaws instead of teeth

Class Osteichthyes - bony fishes

Largest taxon of all vertebrates

Operculum

Paired fins supported by bony pectoral and pelvic girdles

Earliest bony fish had pair of lungs - accessory breathing structures

Two Distinct Lineages of Bony Fishes:

Ray finned fishes - Subclass Actinopterygii

Fleshy finned fishes - Subclass Sarcopterygii

Subclass Actinopterygii

Chondrosteans Neopterygians

(sturgeons, paddlefishes (bowfins, gars and teleosts

bichir) fishes = modern bony fishes; 96% of all fishes)

- Heterocercal tails - - Homocercal tails -

- ganoid scales - ctenoid & cycloid scales;

light and thin - easier to avoid predators

Swim bladders

Physostomous Physocleistous

Class Sarcopterygii

6 species - lung fishes & 1 species - lobe-finned fish, the coelacanth

Diphycercal Tails

Lobe finned fishes = rhipidistians = ancestors of tetrapods.