1. FISH Characteristics Aquatic Scales Fins Ectotherms Pharyngeal slits
Gills
Reproduction (3 methods)
oviparous
lay eggs
external fertilization

2. ovoviparous
internal fertilization
eggs develop within the female
developing embryo nourished by food stored in yolk sac
viviparous
developing embryo is nourished by the mother as it grows
Divided into 3 classes
Agnathans
“jawless”
Hagfish
Myxinoidea
slime, mucus

3. Hagfish relationship to other vertebrates unclear
scaleless, smooth skin
isotonic to seawater
poorly developed osmoregulatory system
eyes degenerate or simple
glands secrete mucus and protein threads
used as defense mechanism
food is swallowed then encased in a mucus bag
food is digested inside bag

6. Lampreys Lampreys Petromyzontoidea petro- = rock; myzo = suck
marine and freshwater habitats
similar to hagfish, no jaws or paired fins
simple vertebrae
well developed osmoregulatory system using gills& kidneys (allows anadromous life )
Migrates upstream to spawn
suction cup mouth with teeth and rasping tongue