Vertebrates: Part I Fishes & Amphibians

Phylum Chordata Chordates: includes all the vertebrates Have 3 common characteristics: –Nerve Cord: hollow tube that hold nervous tissue –Notochord: rod that runs down the back for support (in higher vertebrates it is replaced with the vertebral column) –Throat with gill slits: used for breathing (in higher vertebrates these turn into the trachea)

Phylum Chordata There are 5 groups in the phylum Chordata we will study –3 groups are cold blooded: no internal temp regulation. They take on the temp of their surroundings –2 groups are warmblooded: maintain a constant body temp

Phylum Chordata The 5 Groups: –Fish: cold blooded –Amphibians: cold blooded –Birds: warm blooded –Reptiles: cold blooded –Mammals: warm blooded

Fishes Live in freshwater or saltwater Bone or cartilage protects brain & spinal cord Gills for respiration Mostly external fertilization

Fishes 3 Characteristics: –Scales –Fins –Throat with gill slits Closed Circulatory System Well developed nervous system Keen sense of smell and taste

Classes of Fishes Jawless Fish –Lamprey, Hagfish Cartilaginous Fish –Sharks, rays, and Skates Bony Fish –Most common fish

Jawless Fish Have no bone, only cartilage Flexible Use teeth and their tongue to eat

Cartilaginous Fish No bones, only cartilage Toothlike scales Sharks can have 1000’s of teeth in up to 20 rows

Cartilaginous Fish Skates and Rays use poison or electric volts to stun their prey

Bony Fish Have bony skeleton Most common type of fish Many different species Have paired fins

Bony Fish Swim in Schools Swim Bladders: gas filled sac that gives fish buoyancy

Fish Structure

Amphibians (Amphi- double) Cold Blooded Most have metamorphosis Breathe with gills when immature and lungs and skin when they are adult Use both internal and external fertilization

WHY THEY LIVE ON LAND AND WATER Drying out: skin needs to be moist to breathe Respiration: use gills as a baby Reproduction: eggs don’t have hard shell

AMPHIBIANS 2 Groups –frogs, toads –salamanders, newts

FROGS AND TOADS Hibernate during winter Skin: –Frogs: smooth and moist –Toads: warty and dry Large hind legs for jumping: helps them to escape predators Lay their eggs in water

Frog Life Cycle

SALAMANDER & NEWTS VERY SIMILIAR TO FROGS EXCEPT: –No large back legs: cant jump –Do not hibernate Lay their eggs in water

SALAMANDERS & NEWTS Clawless Have short smooth moist bodies Long tail. They do not have scales.