Sea Acorn. Life Cycle, Reproduction

Sea acorn balanus is a genus of barnacles (suborder of sea acorns). Adult individuals of this biological species conduct a fixed life, attaching themselves to hard surfaces. Settlement is possible only in the larval stage. Currently, about 60 species belong to this genus.

These marine animals (photo below) have a calcareous shell that attaches to the substrate. The shell itself consists of 6 plates, four of which form a lid and have the ability to move apart. The crustacean lies on the bottom of this house, sticking out the limbs between the open plates. At the same time he makes vigorous rhythmic strokes to drive water inside the house with food particles.

In diameter, the sea acorn reaches seven centimeters, and in length - 13. The color is usually whitish or grayish with longitudinal strips of violet or brown.

The sea acorn with its wide soles is attached to any surfaces - shells of mollusks, stones, tree roots, pier piles, bottoms of ships, and also to various animals. Below you can see a photo of sea animals, to which can attach an acorn. The sticky substance that is produced by the sea acorn is very stable. It can withstand temperatures of up to 200 degrees and is not affected by alkalis, acids and other solvents.

In turn, on large leaves of sea acorns, soft sponges are often lodged, for which the crustacean's house is a reliable and solid foundation.

Life cycle of the sea acorn

The development of the sea acorn consists of the following phases: an egg, a larva, an adult crustacean. The larvae emerging from the eggs freely swim and pass through two stages: nauplius and ciprice. In cold-water species, the larval stage lasts from 2 weeks to 1 month, and in tropical ones - about 3-5 days.

The larvae do not feed in the ciprice stage. For a while they swim, but, having got into favorable conditions, attach themselves to the substrate. Adult crustaceans lead a still life.

The sea acorn grows and develops quite rapidly. In the tropical belt, some species already reach maturity within 1-2 weeks after subsidence. In the colder Baltic Sea, this takes about three months. The life expectancy of crustaceans ranges from 1-2 years to 5-7 or more.

How does the sea acorn reproduce?

Cross-fertilization is carried out between the individuals sitting next to each other. The sea acorn is a hermaphrodite, that is, each of them has both male and female gonads. Near the base of the anterior pair of legs, the oviducts open, from which eggs emerge, which then enter the mantle cavity. The vas deferens flow into the tubular bovine male organ, which straightens out during mating, protrudes outward and enters the mantle cavity of the anterior individual. The semen produced by it impregnates the eggs. Studies were conducted, during which it became clear that the sea acorn can reproduce alone. After fertilization, a group of eggs in the mantle cavity are joined into egg-laying plates and proceed to crushing.

Cold-loving individuals form eggs in the summer, fertilize them in winter, so that in the spring larvae leave. Heat-loving individuals lay eggs several times throughout the year.