What is the difference between a sea cockroach and an ordinary one? Relic creature features

Sea cockroach (Latin name - Saduria entomon) is a species of benthic arthropods belonging to the family Chaetiliidae. It is also called the “shutter”. Outwardly, this is an unremarkable creature that seems to many people very repulsive. But, if you get acquainted with the arthropod closely, it becomes clear that this species has a fairly rich history and has its own characteristics.

Description

The length of the largest representatives of the species ever found by humans reaches 10 cm. Such specimens were caught in the waters of the Gulf of Bothnia, located between Sweden and Finland. But usually sea cockroaches cannot boast of such dimensions: in most of them the body length is 5–9 cm. Its color can be beige, sand, gray or light brown, which makes masking at the bottom of water bodies easier.

Despite their modest size, sea cockroaches are officially recognized by biologists as the largest crustaceans that inhabit the Baltic Sea. Representatives of the species also have another “achievement”: they are rightly called glacial relics of this region.

Glacial relics - creatures or plants that have been preserved in a certain area without significant changes in the structure since the last ice age. This is due to the combination of favorable conditions prevailing on the ground.

The body shape of a sea cockroach is a very elongated oval. It is covered with a protective shell formed by durable chitin. The "external skeleton" of the arthropod protects it from many adversities: for example, mechanical damage and the penetration of pathogenic microorganisms. The chitinous cover undoubtedly helped the animal survive unchanged for at least 7000 years. When a sea cockroach grows out of its shell, molting occurs.
The body of the arthropod is formed by several segments, gradually tapering to the tail edge. It has internal and external antennae. On the head of the sea cockroach are gills, eyes and 2 more pairs of sensitive antennae, responsible for the sight and touch of the creature, and therefore for successful orientation at depth, as well as providing nutrition. The antennae help the arthropod find food and identify predatory inhabitants of the bottom, which pose a threat to the sea cockroach.

Habitat

Sea cockroach, steadily survived the ice age, prefers to live in cold waters. Its traditional habitat is the coastal zone of the Baltic Sea, the Arctic Ocean and the North Pacific. He also feels quite well in fresh water: a large number of representatives of the species live in European lakes: in Ladoga and the Swedish Veneren and Vettern.

Sea cockroach is an invasive species of the Black Sea, seen in its water area in 2009.

The life of a sea cockroach

Sea cockroach lives at a shallow depth (up to about 290 m) along the coast. Arthropods spend most of their life at the bottom of a reservoir, preferring soil types such as sand, clay, mud, or gravel. The creature swims badly.

This arthropod can be called universal in nutrition: it does not disdain plant residues, carrion and eating relatives.But the “calling” of a sea cockroach is predation. The animal hunts for small organisms that live at the bottom. For example, Monoporeia affinis (worm-shaped arthropod) and Baltic macomas (Baltic macoma), a bivalve mollusk with a 2-3 cm shell, are ideal victims for it.

Breeding

Sea cockroaches are characterized by bisexual reproduction. After mating with the male, the female lays eggs in the soil of the reservoir.

When the supply of nutrients contained in the egg comes to an end, a larva emerges from it. The first stage of its development is called "nauplius". This is a small creature whose body temporarily consists of only two segments. Such a larva is very vulnerable, because the chitinous cover has not yet hardened, so the nauplius is vulnerable to possible damage and enemies. Gradually, new segments form from the tail edge.

The next stage of development is metanaplus. The trunk of the larva consists of several segments, and the protective skeleton is stronger. As the metanaplius grows, molting occurs, in which the chitinous shell is replaced with a new one, somewhat more spacious. Along with external changes, internal changes also occur.

Sea cockroach and man

Sea cockroach, although not used in cooking, is theoretically edible, like its closest relatives - crayfish and shrimp. The meat of these arthropods is nutritious: rich in protein, micro and macro elements. But the unattractive appearance of a sea cockroach repels many daring gourmets.

The only harm to a sea cockroach for humans is the possibility of it getting into fish products due to poor-quality processing and selection of the catch. An arthropod is often found in fishing nets, and it is not always possible to sort it. This does not cause any damage to the quality of the products, because the sea cockroach is safe for human consumption, but its appearance brings unpleasant emotions from the acquisition.

Sea cockroach is an ancient arthropod that prefers to inhabit the north. Although it spends life at the bottom, meetings with a person often occur. The creature does not harm humans, and it is useful as part of the biological diversity of water bodies by participating in the food chain.