A fish is a cold-blooded animal which is also a vertebrate (animal with a backbone). They are aquatic vertebrates; they have gills and fins and they also live in water their entire lives. This is what makes fish different from other types of animals in the world. There are a few exceptions to the cold-blooded rule for fish. New fish have been discovered that are completely warm-blooded.
How fish breath under water?
Fish have gills which are apart of them since the moment they are born. Gills give fish the ability to breath under water. They are located on both sides of the fishes head and they absorb oxygen which is in the water and they give off carbon dioxide.
Cold-blooded
Being cold-blooded means that fish aren’t able to control their body temperatures on their own. They need the help of their environment to increase their body temperature. The temperature of a fishes body will depend on the temperature of the water they are in. Cold water will make fish sluggish.
Species of fish
The majority of the different fish species live in the Pacific Ocean (the largest ocean in the world). There are over 33,000 species of fish in the world, and some of still being discovered. The different species of fish have adapted to various environments such as rivers, ponds, rocky shores, and the deep sea. The huge number of fish species make then the most diverse group of vertebrates on the planet.
The largest member of the fish family is the Whale Shark. The largest Whale Shark which was discovered was around 21.5 metric tons and had a length of 12.56m.
What do fish eat?
Fish fall into three different categories, these categories are; carnivore, herbivore, and omnivore. The types of food fish need to eat isn’t their choice. Certain species of fish need to eat meat, and others don’t need to. What fish eat depends on their digestive tract, characteristics of their mouths, and their environment.
Carnivores
Fish that are carnivores need to have a protein rich diet. This means they need to eat a lot of meat. The species which fit into this group include Piranhas, Pipefish, and Killifish. Carnivores have larger mouths with sharp teeth that they can use to kill and eat their prey.
Herbivores
Herbivores eat plants, algae, vegetables, and fruits. Fish that are herbivores need to eat more frequently than carnivores as their intestines break up their food and not their stomachs like the carnivores. This is because fish that are herbivores do not have a true stomach.
These fish have flat teeth which that can use to grind up their food before it is swallowed. Fish that fall into this groups include shellfish, tilapia, and catfish.
Omnivores
Fish that are omnivores eat both meat and plants. This means that they also possess digestive characteristics of both carnivores and herbivores. Species of fish that are omnivores include the pupfish and lancet fish. The majority of fish species are omnivores.
