a class comprising cartilaginous fishes with well-developed jaws and including the sharks, skates, rays, chimeras, and extinct related forms
lateral line system
in fishes, a line of sensory organs along either side of the body, often marked by a distinct line of color.
Producing eggs that hatch outside the body.
producing living young from eggs that hatch within the body
Giving birth to living offspring that develop within the mother's body. Most mammals and some other animals are viviparous.
a class of fish having a skeleton composed of bone in addition to cartilage
A female gamete; an ovum.
an air-filled sac near the spinal column in many fishes that helps maintain buoyancy
A member of the subclass Crossopterygii, a group of bony fishes with paired rounded fins, suggesting limbs, that are extinct except for the coelacanths. The lobe-finned fishes are regarded by some as ancestors of amphibians and other terrestrial vertebrates
Any of several elongated freshwater fishes of the Amazon, western and central Africa, and Australia that have lunglike organs as well as gills and are able to breathe air, allowing certain species to survive periods of drought inside a mucus-lined cocoon in the mud.