1. no air filled swim bladder, heterocercal tail,teeth regrow, hyostilic or amphystylic jaws, placoid scales
buoyancy control - oil filled liver
Swim control - heterocercal tail
Body covering - placoid scale, light weight protective, mods for protection
prey detection - appullare of lorenzini
Reproduction - internal fertilization
cartilaginous skeleton, placoid scales, ram ventilation efficient osmoregulated(nitrogen), large rectal gland, internal fertilization, large young