Critter of the Day Common name: Sheephead Scientific Name:Semicossyphus pulcher Phylum Chordata; Class Osteichthyes Draw and note unique characteristics

CLASS OSTEICHTHYES Bony Fish

All classes of Osteichthyes are in one of three subclasses: –Dipnoi (lung fish) –Crossopterygii –Actinopterygii there are more than 23,500 species of bony fishes classified based upon genetics, comparative anatomy, fossil records, molecular biology, and embryology evolved from the jawless fish 450 million years ago

Basic Characteristics of Bony Fish skeletons are rough and bony with numerous vertebrates usually has a homocercal tail (symmetrical tail fin extending beyond the end of the vertebral column as in most bony fish most have a fusiform (round and then tapering at the ends) body type can fluctuate from 3 different forms of fusiform body shape: 1. Compression 2. Depression 3. Elongation common to have a laterally compressed body shape for protection in areas of low coverage have terminal mouth and flap covering gills

Osteichthyes Locomotion:

LOCOMOTION!!!!! Sequential inside-to-outside contractions along one side of the body with simultaneous relaxation along other side propulsion from other fins than just the body

LOCOMOTION!!!!!! body shape and fin location highly variable body design for high speed swimming minimize surface area exposed to fluid: sphere minimize cross-sectional area pencil shape

LOCOMOTION? minimize retarding force: teardrop (torpedo) shaped = tuna also inset eyes and slime reduce friction small scales or scaleless Slow- fewer fins Faster- more fins - propolusion