Phylum Chordata• Notochord…flexible rod that

gives support during development

• Usually disappears whenbackbone develops

Lancet

Subphylum Vertebrata

• Vertebrae (backbone ) made ofbone or cartilage

• Skull that protects the brain• Endoskelton made of bone or

cartilage

Fish• Adapted to live in water

– Streamlined shape– Muscular tail– Paired fins (ventral, dorsal, pelvic, pectoral

and caudal)– Mucus secretions to decrease friction

• Chemoreception (“smell”)…sense chemicals in water

• Lateral line…small canals in skin tosense vibrations in water

Jawless Fish• Class Agnatha• Includes hagfish and lampreys• Eel-like bodies, skeleton of

cartilage, unpaired fins• Parasites…feed off of other body

fluids…scrape through skin

hagfish

lamprey

Cartilagenous Fish• Class Condrichthyes• Sharks, rays, skates• Skeleton entirely of

cartilage…flexible, lightweight• Skin has placoid scales …tooth

like spines• Reproduce by internal

fertilization, lay eggs or live birth

Sharks, rays, skates

Sharks, rays, skates

Placoid scales

Bony Fish• Class Osteichthyes• Skelton made of bone• Swim bladder for buoyancy• Gills for gas exchange (a few have

lungs)• Smooth scales cover body• Lobe-finned fish…have flesh parts

to fins• Ray finned …no flesh in fins, most

fish you know

Lobe finned fish• Coelocanth• Lungfish

Ray finned fish

Bony Fish• Circulation: 2 chambered heart,

closed system with arteries, veins and capillaries

• Kidneys and gills for excretion• Well-developed brain• External reproduction, lay eggs

in a mass

Egg mass

Amphibians• Class Amphibia• Live part of live on land and part

in water• Frogs, toads, salamanders• Indirect development

(metamorphosis)

Amphibians• Respiration:

– through moist, thin skin, no scales, mucus layer to keep moist

– with gills– with lungs

• Circulation: 2 circulatory systems– Pulmonary… heart to lungs and back– Systemic… heart to body and back– 3 chambered heart … blood mixes

Amphibians• Webbed feet, no claws• Lungs, gills and skin for

respiration!• Internal fertilization, egg mass

•Order Anura– “tail less”– frogs, toads

Amphibians• Kidneys for excretion• Well developed brain & senses

of sight (nictitating membrane protects eyes underwater),

smell, hearing (tympanic membrane)

Amphibians

•Order Caudata– Salamanders

• Order Gymniophona– Caecilian (look like legless snakes)

Anura… “tailless”

Caudata (salamanders)

Gymnophiona (caecilian)

Amphibianmetamorphosis

Spring peeper

Not all amphibians undergo metamorphosis, but the ones that do have similar steps