Bony FishBony fish have three key characteristics:
External AnatomyAll bony fish have a distinct head, trunk, and tail. On each side of the head is the operculum, a hard plate that opens ate the rear and covers the gills. Scales are thin, round disks of bone-like material that grow from pockets in the skin.
|
Feeding/DigestionMost are carnivorous, many are herbivores, but they can also be predators, scavengers, or parasites. They have well developed teeth for capture and holding.
The digestive system contains:
|
Sensory/Nervous SystemThe central nervous system is compromised of a brain and spinal cord.
At the nose end of the fish lie olfactory lobes, which provide sense of smell. A fish's spinal cord transmits motor messages to its peripheral nerves, and sends sensory messages back to the brain, the various nerves of the peripheral nervous system branch throughout the body. |
Excretion/
|
Movement/LocomotionRhythmic side to side motion of the caudal fin moves the fish. Bony fish have a specialized organ filled with gas, called a swim bladder. This organ helps the fish to maintain buoyancy. The dorsal and anal fins provide steering and stability, which keeps the fish from rolling. The pectoral and pelvic fins help it to turn, balance, and stop.
|
Transport/CirculationThey have a closed circulatory system with a two-chambered heart. The single loop circulatory system has one ventricle and one atrium.
|
ReproductionEggs are produced by ovaries in the females and sperm is produced by testes in the males. Both are released through an opening behind the anus. Fertilization happens almost exclusively externally. Their spawning behavior varies wildly between species.
|
Support/SkeletonTheir skeleton is made of bone and cartilage. The vertebral column, cranium, jaw, and ribs make up a bony fish skeleton.
Fin muscles consist of abductor and adductor muslces that move the fins away from and close to the body. The erector muscle provide stability and flexibility in the fins. The skeleton of the fish gives structure, provides protection, and assists in leverage. It is also the site of red blood cell production, as well as the spleen and liver. |
Oxygen IntakeMost bony fish use gills, which are feathery structures that allow high surface are for rapid gas exchange.
|
Habitat/LifestyleThey live in both marine and freshwater. Some fish are diadromous - meaning they migrate from freshwater and seawater.
Fish that are anadromous live in sea water as adults but spawn in freshwater (ex: salmon). Catadromous fish live in freshwater as adults but spawn in the ocean. Amphidromous fish spend their lives in seawater and in freshwater. |