Crayfish are the orderlies of the environment in which they live. Most cancers, including hermit crab, live in seas and rivers, but among the hermits there are not only deep-sea, but also land species.
Cancers are called orderlies because they are omnivores. Young individuals live in the ebb-tide, where it is easier for them to find food. Among the algae, they collect all carrion, including animal remains. They eat like real gourmets: slowly bite off a small piece with a claw and eat it.
One female can lay up to fifteen thousand eggs during the year. She attaches the testicles to her abdomen and takes care of them, constantly raking fresh, oxygenated streams of water into the abdomen. In ten days, larvae emerge from the eggs, which have to go through four stages of growth.
The body of all young cancers is covered with a dense shell. It is impossible to grow in it, therefore periodically young crayfish discard the shell and, having increased in size, are again covered with a new shell. On the fourth molt, the hermit cancer loses part of its carapace in the abdomen forever. Its long abdomen is covered with skin, bent under the breast and takes the form of a shell.
As if ashamed of such shame (at the same time fearing to become the prey of other
crayfish), the hermit crab searches for a comfortable
shell , thrown by
mollusks and puts its soft abdomen in it, and leaves its head and claws outside, but only until there is danger. In case of danger, he squeezes the whole into the shell and covers the entrance to it with his right claw covered with a thick shell, the good thing is that the structure of the hermit's cancer allows him to be conveniently located in shells of any configuration.
Other
types of cancers continue to molt and grow. They live compactly. But hermit crabs are their exact opposite. They are loners. But meanwhile, they love the society of other creatures. For example, deep-sea hermits allow amazing and very poisonous fish - sea anemones to settle on their shells - therefore their shells seem shaggy. Cancer willingly runs in a shell with sea anemone and feeds it with the remnants of its food. Although poisonous sea anemone often causes the death of a predator that targets cancer living in a shell. And then he eats it with cancer. Land loners allow the multi-bristled worm to settle in their “houses”, creating such a unique hostel that gives both shelter and protection from predators. The worm does not allow annoying insects in the shell, and the cancer protects the worm from amphibious predators.
The digestive system of the hermit crab is very interesting. From the mouth, through the throat and esophagus, its food enters the first part of the stomach, equipped with serrated chitinous graters. Grated food enters the second section, where it is filtered and enters the intestines, passes through the digestive gland, where it is digested. The hermit crab breathes with gills associated with its limbs. The eyes have a very complex structure, as they consist of many separate optical lenses collected in one eye, so his vision is mosaic.