Crustaceans

Crustacea is a category of arthropods that contains the following more popular critters: crabs, lobsters, shrimps, crayfish, crayfish, woodlice, and barnacles. There are currently around 70,000 species free to choose from. Crustaceans formed in the plurality and according to the present period, are represented by a single subtype of arthropods, for which the aquatic sphere appears as the main. A number of dungiferous crustacean species are included (e.g., dungeness crabs, dungeness crayfish, and woodlice), but also a number of parasitic taxa (e.g., whale louse and fish louse). Most crustaceans are dynamic in nature, but some categories, such as the barnacles, are sedentary.

Description
The body of crustaceans is divided into subsequent divisions: the main, thoracic and abdominal. ONLY certain varieties, the head and also the deep section are fused together (thorax). Crustaceans have an outer skeleton (exoskeleton). Skeleton (outer layer) is often reinforced by calcium carbonate, which guarantees auxiliary skeletal aid (especially important for large species).

Numerous crustacean species have 5 fog appendages in the body (for these belong: 2 vapor antennae (antennae), a couple of vomer jaws (maxillae) and a couple of higher jaws (mandibles, or mandibles)). Uncomplicated eyes are placed at the end of the stalks. The deepest section includes a number of pereiopods (walking scapulae), but a segmented abdomen of the pleopods (abdominal scapulae). The posterior outcome of the crustacean torso is called the telson. Larger crustacean types have a range of gill support. Smaller types to perform gas exchange use the plane of the body.
Reproduction
Most species of crustaceans – and mole sex and reproduce sexually, although some categories, such as a succulent, remipedias and cephalocarids – hermaphrodites. Actual period of crustaceans comes along with the fertilized egg, which either released directly into the water or attached to the sexual organs or legs of the female. After hatching from the egg, the crustaceans go through a series of formation steps, initially before transforming into an adult individual.

Food chain
Crustaceans occupy a central position in the marine food chain, and are also among the best known animals on our planet. They feed on organisms such as microphytoplankton, in turn, crustaceans are made food for the larger animals, such as fish, but individual crustacean agents, for example crabs, lobsters and shrimps are a very popular food provision for humans.

Size
Crustaceans come in a wide variety of sizes from small hydrophilic fleas and crustaceans to the large Japanese spider crab, which is about TWENTY kilograms long and can be 3 to 4 meters long.
Nutrition

In the course of their development, crustaceans have developed an extensive range of feeding methods. Some types are represented by filter feeders that extract macroplankton from the water. Other types, especially the larger ones, are active predators that keep and also tear their own prey with the support of strong appendages. Occur also scavengers, especially of the smaller species, feeding on the decaying remains of other organisms.

The first crustaceans

Crustaceans are well represented in the paleontological record. The original crustacean agents belong to the Cambrian stage and are also presented as old, cut down in the Burgess Shale formation, located in Canada.

Classification
Crustacea are divided into 6 classes:

Branchiopoda;
Cephalocaridae;
Malacostrac;
Maxillopoda;
Ostracoda;
Remipedia.