Instead of scales a shark’s body is covered in tiny ‘skin teeth’! These teeth make a sharks skin feel like sandpaper.

Something fishy!

Fish is the general term used to describe a huge group of animals that live in water and have a backbone, cold blood, gills and fins. There are three main groups of fish; bony fish (e.g. salmon), cartilaginous fish (e.g. sharks and rays) and jawless fish (e.g. hagfishes).

Breathing and floating

Fish use gills to breathe the oxygen in water. Water flows over the gills from pairs of flap like openings on a fish’s head. Bony fish have one gill opening while sharks and rays have 5-7.

Fish are heavier than water! To help them stay afloat bony fish have an air filled sac called a swim bladder, and sharks have a large oily liver.

Scales and Slime

Most fish are covered in thin overlapping plates, called scales, which protect their skin. On top of these scales is a layer of slime! Slime helps fish to swim faster and stay healthy by acting as a barrier to parasites and a liquid bandaid!


Fish have 5 sets of fins each with its own role. The side fins are normally used for steering, the tail for propulsion and the other fins for stability.

Fast or slow?

The shape of a fishes tail can tells us how fast it usually swims. Fish with forked tails, and a narrow base, are fast swimmers. Slow swimmers have rounded tails with a wide base.


Bony fish have very flexible fins compared to cartilaginous fish.