Question

List three features that characterise bony fishes.

Answer 1

Both bony fish and cartilaginous fish breathe through gills, but bony fish also have a hard, bony plate covering their gills. This feature is called an operculum. Bony fish may also have distinct rays, or spines, in their fins. And unlike cartilaginous fish, bony fish have swim bladders to regulate their buoyancy. (Cartilaginous fish, on the other hand, must swim constantly to maintain their buoyancy.)

Bony fish are considered to members of the class Osteichthyes, which is subdivided into two main types of bony fish:

Ray-finned fishes, or Actinopterygii
Lobe-finned fishes, or Sarcopterygii, which includes the coelacanths and lungfishes.
Bony fish include both marine and freshwater species, while cartilaginous fish are only found in marine environments (salt water). Some bony fish species reproduce by laying eggs, while others bear live young.

Answer 2

A lung or swim bladder helps the body to create a balance between sinking and floating by either filling up with or emitting gases or oxygen. Controlling the volume of this organ helps the fish to control their depth.

A cover over the gill called the operculum helps them to breathe without swimming.

Jointed, segmented rods support the fins.

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