An aquatic version of the lobster is crayfish. Their meat is considered valuable in Europe. In Europe, the first supplier is Norway, while France is the first buyer. The meat from the belly and claws is what is eaten by the crayfish.
These crustaceans have perfect vision, and they can shift their eyes freely of each other, like other associated animals. At the end of June, crayfish moult. In order to regain the calcium and phosphates found in it, they typically ingest their old skeleton.
Crayfish typically have two limestone grains on the edges of their stomach, filtered out of the water, which help to impregnate the fresh developing skeleton with calcium. The plant matter is consumed by these crustaceans, but also by insects, prawns, insect larvae, small fish, and carriages.
Crayfish walk forward; they step backward with their abdominal motions only while swimming. Even, it's much easier to swim backwards. In around four years, adult size is attained by crayfish in the wild. About 20 to 30 years, they will live. During the breeding season, males battle for the opportunity to interbreed and can lose limbs or claw in these fights.
Crayfish sperm is particularly unusual: it is absolutely absent of flagella (tails). It appears like amebas, and the eggs move toward them. They are also particularly susceptible to pests such as the plague and plague of crayfish. The red swamp crayfish (Procambarus clarkii) was brought into Europe in 1974 from the southeastern US. In this way, the American crayfish have killed countless European crayfish species.
Although detritus (organic waste) is eaten mostly by the local species, preserving a safe water setting, the red one sweeps out everyone else: fish eggs, hatchlings and algae; it also digs deeper into the soil, causing erosion, and grows faster than the local species.
The mantis shrimp is a peculiar tropical crustacean: it has an insect-like trapping apparatus called the praying mantis, but the edges are very sharp, and the function is one of the fastest in the animal world: it can slice a fish, another shrimp or even a person finger in a couple of seconds.
The polarised light, colours, and can shift its eyes independently at 180o to detect its prey or predators are also seen by this shrimp. It is said that this shrimp has a trinocular vision, with its visual receptors located in separate parts, upper and lower.