The average life span of barnacles is about 8 – 20 years. The barnacles are an infraclass whose representatives (total about 1200 species), although they belong to the group of crustaceans, are significantly distinguished among other relatives. These marine animals have moved to a sedentary lifestyle, and some even parasitize on the body of other animals (sea stars, jellyfish, ordinary crayfish, etc.). However, most of them are represented by free-living forms, in particular sea acorns and sea points.
These cancers are called barnacles because their limbs, which serve for catching and filtering food particles from water (and also performing respiration function), have been transformed into long thin mustache-tentacles consisting of 20-30 segments and covered with frequent bristles. The body of barnacles is covered with a chitinous shell, consisting of a different number of plates impregnated with lime.
Some of these plates are mobile and allow the cancer, if necessary, to be firmly locked inside its shell, as in a house. So they can transfer temporary extraction from water or salinity drops, and also hide from the attack of predators. When everything is quiet, the doors of the house are opened, and out of the slot protruding tentacles protrude outward, with which the cancer catches food particles and directs itself to the mouth.