The document summarizes key characteristics of bony fishes. It describes that bony fishes have over 27,000 species, an endoskeleton of true bone, and are found in all marine habitats. It then outlines some of the major types of bony fishes including lobe-finned fish and ray-finned fish. Mobility, buoyancy, gas exchange, senses, reproduction and protection mechanisms are also summarized.

1. The Bony Fishes
Class Osteichthyes

2. Class Osteichthyes – The Bony Fish
• More than 27,000 species
• Most numerous and successful of all
vertebrates
• Found in every marine habitat
– tide pools to deep sea
• Economically important
– 77 million tons harvested per year

3. General Characteristics
• Endoskeleton made of true bone
• Hinged jaws
• Paired fins – independently movable

4. Types of Bony Fishes
• Lobe-finned Fish:
– Ancestors of amphibians
– Ex: coelacanth – thought extinct 65 million years
ago – found live in 1938 – 2 species
– Ex: lungfish – lung that can breathe air during
droughts
• *Ray-finned:
– Most present day fish

5. Movement
• Nektonic – swimmers - control
movement against current
–Move to food
–Escape predator

6. Movement
• Streamlining to reduce drag = teardrop shape =
fusiform
• Most fish swim by moving tail side to side
• Mucus reduces drag
• Homocercal tail – top and
bottom same size
yellowfin tuna

7. Buoyancy
• Gas-filled swim bladder – to maintain position
in water
• Control quantity of gas
• Not present in fast moving fish or sharks

8. Gas Exchange
• Gills covered by operculum
• Water pumped through mouth, over gills, out
gill slits and operculum
• Thin membranes and high surface area in gills
• Oxygen diffuses from water into blood
• Carbon dioxide diffuses from blood to water
striped bass

10. Osmoregulation
• Maintenance of water balance
• Saltwater fish tend to lose water
• Drink seawater
• Excrete salt from gland in gills
• Produce little urine

11. Osmoregulation

12. Senses
• To find prey and avoid being eaten
• Good sense of sight, smell and taste
• Good sense of hearing – inner ear
• Lateral line system:
– Line of pores and canals running down body
– Detect vibrations, changes in current direction
and water pressure

13. Outer Covering
• Mucus – reduces friction and prevents
infection
• Scales – protective outer cover
– Overlap like roof shingles
– Can tell age of fish

14. Outer Covering

15. Reproduction
• Separate sexes
• External fertilization = spawning
– Female releases eggs
– Male releases sperm on top

16. Protection
• Camouflage
ex: flounder, sea dragon,
sargassum fish

17. • Armor plating Protection
ex: seahorses
• Size
ex: puffer fish
• Spines
ex: blow fish

18. Protection
• Countershading - dark on top, light colored on
bottom
• Disappear, ex: flying fish – leaps out of water
• Deceptive markings, ex: butterfly fish

19. • Schooling Protection
– ¼ of all species at some point in life
– Looks like one large individual
– Confuses predator
– Hard to catch one fish
– Easier feeding
– Easier mating

20. Other Fish Adaptations
• Angler fish – lure to attract prey
• Deep sea fish – bioluminescence

21. Fish Oddities
• Some start life as male, change to female or
opposite – ex: some grouper, sea bass,
sheepheads, wrasses
• Ocean sunfish – Mola mola - planktonic