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