Cartilaginous Fish

Cartilaginous fish are a special group of fish that have skeletons made of cartilage instead of bone. It's the same flexible material found in your ears and nose.

This group includes sharks, rays, and skates. Since they lack bones, they produce red blood cells in the spleen. In some species, it is produced in a special organ called Leydig’s organ.

Their skin has tiny, tooth-like scales called placoid scales. These make their skin feel rough, like sandpaper, and help them swim faster by reducing drag in the water.

Another feature is their teeth, which vary in shape depending on what they eat. For example, great white sharks have sharp, pointed teeth for catching prey, while rays have flat teeth for crushing shells.

To breathe, cartilaginous fish use multiple exposed gill slits present on the sides of their heads, which allow water to flow over their gills.

So, how do these fish reproduce underwater? Most cartilaginous fish reproduce through internal fertilization. Some lay eggs, while others give birth to live young.