Superclass Agnatha "Jawless Fish"

No jaw No paired appendages Cyclostomes (round mouths) Smooth, cylinder shaped bodies with flexible skeleton of cartilage Two chambered heart

Extinct ostracoderms- heavy bony plates

Class Myxini Hagfish

Bottom dwellers in cold water Mucous secreting glands (slime eels) Poor eyes covered with skin

Monoecious (sequential) Slit-like, toothed mouth Scavengers- locate food by scent

Have ability to tie themselves in knots Clean body of slime (even nostrils) Escape predators Move food down digestive tract

In Korea, almost 5 million pounds are eaten each year Used to make “eelskin” products

Class Cephalaspidomorphi lampreys

Cool, fresh coastal waters 1-2 fins that extend length of body Single nostril on top of head Well developed eyes

Mouth- oral disc with sharp, rasping teeth Scrapes hole in side of fish and sucks blood and tissues (usually kills fish) Major economic threat

Lays eggs in hollowed out bottom of lake External fertilization Wormlike larvae that burrow for 3 years Metamorphosize to adult Most adults in ocean- many reproduce in freshwater

Superclass Gnathostomata Coelocanth Jaws and paired appendages

Class Chondrichthyes Cartilage Fish

rays sharks ratfishes skates

Most marine Most carnivores or scavengers (some filter) Skelton of cartilage Dermal placoid scales (sand paper)– do not overlap

Teeth modified scales- never ending supply (300 rows) Tooth size can be used to find length of shark (proportional)

Countershaded (top dark, bottom light) for camoflage

2 chambered heart Large liver with much oil/fat for buoyancy (no swim bladder) Gill slits (5-7) covered with skin- most must move constantly to obtain oxygen Streamlined and powerful

Acute senses Lateral lines with ampullae of lorenzini sense vibrations (hear) 2/3 of brain for olfactory sense (smell) Sight not great

Internal fertilization Some oviparous, some ovoviviparous, some viviparous

Most species harmless to human- only a few species will attack 50-75 attacks per year 8-12 deaths per year

Humans kill 200,000,000 sharks per year!

Class Osteichthyes bony fish

Largest class of vertebrates Bony skeleton, paired appendages Scales that overlap Fresh and salt water

Most streamlined- swim with side to side movement of body and tail

Complex nervous system- 10 pairs cranial nerves extend from brain Well developed eyes, nostrils, lateral lines Usually 4 pairs gills covered by operculum (bony flap) that pushes water over gills

Two chambered heart Most of body muscle Swim bladder- gas filled sac for buoyancy Separate sexes- most external fertilization

Pufferfish

Fishery Bycatch

Anglerfish