Ventral nerve cord
Dorsal nerve cord
Give them buoyancy
Function well in or out of water.
Are composed of scales.
Are housed in chambers on each side of the head.
Has skin covered by overlapping structures called scales.
Has many small scales embedded in its skin.
Feeds parasitically on other fish.
Has a skeleton made of bone.
Lateral line system
All of the above
Moist and watertight
Moist and thin
Dry and nearly watertight
Dry and permeable to water
Hold the embryo in place, preventing premature loss.
Carry nutrition to and remove wastes from the embryo during development.
Surround and protect the embryo like a shell.
Maintain a constant internal temperature.