Crabs are a kind of crustaceans, which are common in daily life.As a crustacean, crabs are also a kind of invertebrate, which is a relatively low animal.Nevertheless, there are some basic structures in their bodies, and the heart is one of them.Crabs also have hearts, are shaped like hexagons, and are white in color.Specifically, the heart of crabs is located in the center of their body, and there will be a layer of black film-like material on the outer layer, below which is their heart.If their bodies can be cut open, their hearts can be more clearly observed.
As mentioned above, the crab is a crustacean among invertebrates. It is a relatively lower animal, so many advanced structures do not exist in their bodies, such as lungs.Lungs are the respiratory organs of some animals, the efficiency of breathing with lungs is relatively high, mammals and birds and other advanced animals have lungs to breathe.Crabs, however, do not have this structure, and they use gills to breathe like other crustaceans.The gills of crabs are filaments on both sides of their bodies, which are more obvious.
Because they breathe with their gills, they can breathe freely in the water.At the same time, because their gills can store some water, when crabs climb to the shore, they can breathe for a while, of course, not too long.
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