There are many varieties of fish. Some live in freshwater and some live in salt water. There are also some species of fish that live in both environments. Fish can be as small as 7mm, like the Paedocypris fish, or as long as the whale shark measuring an amazing 65 feet in length. Not all fish have scales, but many species do. Why do fish have scales and are all scales the same? Read this article to find out.
Why Fish Have Scales
The main reason that a fish has scales is to provide external protection to its body. They are tough, slippery and hard making them excellent protection for the environments that fish live in. Scales also allow for fish to be flexible. Fish need to move their bodies in a different way to other animals and scales allow them to do this. Fish that don’t have scales often have other defense mechanisms such as a mucous coating or tough leathery skin.
Types of Fish Scales
Fish can have different types of scales depending on where they live and what they look like. There are four main types of scales Placoid, Cosmoid, Ganoid and Cycloid and Ctenoid. Placoid are spine like scales that give a fish a rough texture. This type of scale is most often found on sharks and rays. Cosmoid scales are rounded, bone like scales that grow with the fish. Cosmoid scales are found on fish that belong to the lungfish family. Ganoid scales are rhomboid in shape and are found on fish such as gars, paddlefish, Bowfish, sturgeons and bichirs. Cycloid and Ctenoid scales are semi-circular in shape and have fine comb like protrusions on the edges. They overlap one another and give fish with this type of scale greater flexibility than those with Cosmoid or Ganoid scales. Cycloid and Ctenoid scales can be found on bony fish such as the paradise fish or lionfish. These scales grow along with the fish, so the scales can be used to tell the age of the fish.
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