Fish do not have eyelids, with the exception of the shark. Eyelids are used to protect the eyes from dust and keep them moist; fish do not have these problems underwater, so there is no need for eyelids.Continue Reading
Although fish do not have eyelids, they can sleep. Some float, while others bury themselves or wedge themselves into tight places. Even though they are sleeping, they are still able to sense danger. Fish sleep for as long as they need, depending on how much energy they have exerted during the day.
Fish also lack eyelashes, as they are unnecessary for survival or comfort.Learn more about Fish
Fish jump in order to move through their habitat, catch flying prey and escape predators. Leaping allows them to travel upstream and avoid obstacles. Fish caught on a hook by fisherman often jump out of the water in an effort to dislodge it. Aquarium fish jump out of their tanks due to fear, to escape dirty water or to amuse themselves.Full Answer >
Fish gills act as the equivalent of a mammal's lungs by taking in oxygen and releasing carbon dioxide. Oxygen and carbon dioxide travel across small, thin-walled blood vessels in both lungs and gills. In terms of evolution, gills are significantly older than lungs.Full Answer >
Fish can be omnivores, but some species are carnivores or herbivores. In general, a fish's diet is determined mostly by its habitat and what food is available. Most species have a preferred diet but will eat outside of that if necessary for survival.Full Answer >
Fish live in the water and breathe by absorbing oxygen through their gills. Fish are cold-blooded animals, so their internal body temperature is influenced by the environment. Many fish have scales and use their fins to swim. Fish have a spine but do not have external ears or eyelids. Fish also have air bladders, which keep them afloat.Full Answer >