Vertebrates: Fish

Fish are vertebrates that live in water and have gills, scales and fins on their body.  There are a lot of different fish and many of them look very odd indeed.  There are blind fish, fish with noses like elphants, fish that shoot down passing bugs with a stream of water and even fish that crawl onto land and hop about!

 

 

Fishes have a skeleton made of bone but some, like sharks, have a skeleton made of cartilage. About 95% of fishes have skeletons made of bone. These bony fishes have a swim bladder, a gas-filled sac, which they can inflate or deflate allowing them to float in the water even when not swimming. Fishes with a cartilage skeleton tend to be heavier than water and sink. They must swim to keep afloat. Cartilaginous (cartilage) fish include the ray and the shark.

Most fish breathe through gills. Gills perform the gas exchange between the water and the fish's blood. They allow the fish to breathe oxygen in the water.



*Fun Fact*

·         Most fish, except for sharks, do not have eyelids.
 

·         Tuna is a warm-blooded fish.