Shrimp are one of the healthiest foods. These crustaceans are distributed throughout the seas and oceans, they can be found even in fresh water reservoirs. Unique arthropods are perceived primarily as a nutritious delicacy, an ingredient in various dishes, but shrimp themselves are very unusual and even mysterious inhabitants of the underwater world, with a special body structure. Many lovers of scuba diving in tropical waters have the opportunity to follow their behavior – if you stir the algae, the shrimps jump out like grasshoppers from ordinary grass.
Origin of the species and description
Shrimps are crustaceans from the decapod order, there are 250 genera and more than 2000 different species of these creatures. Decapod shrimp are the highest crustaceans, unlike other multicellular organisms, their heart muscle has a symplastic structure. Like all arthropods, they belong to the animal kingdom, they have a chitinous exoskeleton, which limits the growth of the body and therefore the animal must periodically shed it – molt.
There are about a hundred species of shrimp that are the subject of fishing, some are cultivated on special shrimp farms, there are several species that are successfully kept even in home aquariums. For many species of these crustaceans, protandrous hermaphroditism is characteristic – during their life they are able to change their sex. This unusual phenomenon of separate appearance of opposite sex characteristics in hermaphrodite creatures is quite rare.
An interesting fact: Shrimp meat is especially rich in protein and high in calcium, but is low in calories, however, shrimp, like all other arthropods that live in the seas, are forbidden to be eaten in Judaism. There are disagreements about the permissibility of eating these crustaceans in Islam.
Appearance and features
The color and size of the shrimp depends on its species, but in all these crustaceans, the body is covered on the outside with a continuous, durable layer of chitin, which they change as they grow. The mollusk has a body elongated along the length, flattened on the sides, which are divided into the abdomen, cephalothorax. The cephalothorax, in turn, has an unusual protrusion — rostrum, on which you can see teeth of various shapes, depending on the type of crustacean. The color of shrimp can be from gray-green to pink and even blue, with characteristic stripes, spots, the size ranges from 2 to 30 centimeters. Shrimp eyes consist of a large number of facets, their number increases with age. Their vision is mosaic, and for this reason, crustaceans see well only at a small distance of up to several centimeters.
However, the eyes are responsible for the production of special hormones that regulate:
- body color changes;
- growth, shedding frequency;
- metabolism, rate of calcium accumulation;
- pigment order.
Anterior antennae antennae are the organ of touch. The abdomen of the shrimp is equipped with five pairs of legs – pleopods, with the help of which the animal swims. The female carries eggs on pleopods, moving, they wash and clean them. The last limbs form a wide fan together with the tail. By bending the abdomen, this crustacean is able to quickly swim back in case of danger. The shrimp has three pairs of mandibles of the thoracic limbs, with their help it collects food and brings it to the mandibles, the bristles of which determine — have it or not.
The front pair of legs of mollusks is turned into claws. Shrimps defend themselves with them, grab large prey. In males, they are usually more developed. Walking legs on the chest are interesting in that the left and right legs of each pair always move independently of each other. The gills of the shrimp are hidden by the edge of the shell and are connected to the pectoral limbs. Water is driven through the cavity of the gills with the help of a large blade located on the hind jaws.
Where does the shrimp live?
Shrimp, playing an important role in the ecosystem of the oceans and seas, settled almost everywhere.
More than 2000 species of these crustaceans can be divided into the following subspecies:
- freshwater – found in Russia, Australian waters, South Asia;
- cold water shrimp — this is the most common species that lives in the North, Baltic Sea, Barents, near the coast of Greenland, Canada;
- warm-water mollusks – in the southern oceans and seas;
- brackish – in salt waters.
Chilean crustaceans settled along the entire South American coast, are found in the Black, Mediterranean Sea, and “royal” shrimps — in the Atlantic Ocean. When creating comfortable conditions, some freshwater and warmwater species are successfully kept in home aquariums. Many of them were bred artificially, have an unusual color that does not occur in nature.
An interesting fact: Cold-water shrimp can only breed in their natural environment and are not amenable to artificial cultivation. The crustaceans feed only on environmentally friendly plankton, which determines the high quality and value of their meat. The most valuable representatives of this subspecies are the northern red and red comb shrimp, northern chilim.
Now you know where the shrimp is found. Let's see what they eat.
What does a shrimp eat?
Shrimps are scavengers, the basis of their diet — almost any organic remains. In addition, crustaceans love to feast on plankton, juicy algae leaves, they can hunt young small fish, even climb into fishermen's nets. Shrimp search for food with the help of smell and touch, turning their antennae antennae in different directions. Some species actively tear up the ground in search of vegetation, while others run along the bottom until they stumble upon some kind of food.
These mollusks are practically blind and are able to distinguish the silhouettes of objects only at a distance of a few centimeters, so the sense of smell plays the main violin. The shrimp pounces on its prey sharply, grabbing with its front pair of legs, and holding it until it calms down. Developed jaws or mandibles gradually grind food, which can take up to several hours.
Interesting fact: At night, all shrimps brighten, becoming translucent, and darken in daylight, and so they quickly change their color depending on the background.
For aquarium shrimp, specially prepared formulations or ordinary boiled vegetables are used as food. Not a single crustacean will deny itself the pleasure of eating the remains of its fellows or any aquarium fish.
Peculiarities of character and lifestyle
Shrimp are very mobile, but secretive creatures. They constantly move along the bottom of reservoirs in search of food and are able to overcome fairly large distances, as mollusks crawl along the leaves of underwater plants, collecting carrion on them. At the slightest danger, crustaceans hide in thickets, soil, among stones. They are cleaners and play an important role in the ecosystem of the oceans. They attack their relatives extremely rarely and only in cases of severe hunger in the absence of a sufficient amount of the usual food.
They skillfully maneuver thanks to walking, swimming legs located on the chest and abdomen. With the help of tail stalks, shrimp are able to jump sharply over a sufficiently large distance, quickly move backwards and scare away their enemies with clicks. All shrimp are solitary, but, nevertheless, crustaceans are found mainly in large groups. Some species are active at night, while others hunt only during daylight hours.
Interesting fact: The genitals, the heart of the shrimp are located in the head area. Here are the urinary and digestive organs. The blood of these crustaceans is light blue in the normal state, but becomes colorless when oxygen is deficient.
Social Structure and Reproduction
On average, a shrimp lives between 1.6 and 6 years, depending on the species. Shrimp are bisexual, but male and female glands form at different times. First, at the onset of puberty, the young shrimp becomes a male and only in the third year of life changes sex to the opposite.
During puberty, the process of egg formation starts in the female and at the initial stage they resemble a mass of yellow-green color. When fully prepared for mating, the female releases special pheromones, by which the male finds her. The whole mating process takes a few minutes and after a while eggs appear. Interestingly, females hold unfertilized eggs on the hairs of the abdominal legs, and then carry the offspring with them until the larvae appear from the eggs.
Depending on the water temperature, the larvae develop inside the eggs within 10-30 days, passing from 9 to 12 stages of embryogenesis. First of all, the jaws are formed, then the cephalothorax. Most of the larvae die during the first day and maturity reaches no more than 5-10 percent of the total brood. Under artificial conditions, the survival rate is three times higher. The larvae themselves are inactive and are not able to search for food on their own.
Natural enemies of shrimp
A huge number of shrimp die at the larval stage. Whale sharks, whales and many other planktivorous feed on these crustaceans. They are often prey for other molluscs, seabirds, demersal fish, and even mammals. Shrimps have no weapons against their enemies, they can only try to run away in case of danger or hide among the leaves of plants, in extreme cases, crustaceans can try to scare their enemy and, taking advantage of his confusion, slip away. Shrimps, having camouflage colors, are able to imitate the color of the sandy bottom, as well as, if necessary, quickly change color depending on the environment and type of environment.
Shrimps are also an object of commercial fishing. In huge quantities, these mollusks are caught in the Atlantic Ocean, the Mediterranean Sea. Each year, more than 3.5 million tons of shrimp are harvested from salt water using bottom trolling, which completely destroys the habitat of crustaceans for up to four decades.
Interesting fact: There is no species under the scientific name “royal” shrimp, as all large species of these arthropods are called. The largest species is the tiger black shrimp, which can reach 36 cm in length and weigh up to 650 grams.
Population and species status
Despite the huge number of natural enemies, the low survival rate of larvae and active fishing, the status of the species is currently stable and there are no fears that this type of crustacean will disappear completely. Shrimps have incredible fecundity, are able to quickly restore their population — this is what saves them from complete extermination.
There is a theory that shrimp can independently regulate their population:
- when it grows too much and food becomes scarce — they begin to breed less often;
- with a significant drop in numbers, mollusks multiply much more actively.
Most of the extra large and even giant shrimp, reaching 37 centimeters in length, are grown on shrimp farms. Due to the peculiarities of the functioning of farms, the specifics of nutrition, the meat of these crustaceans is filled with various chemicals. The best quality shrimp are those grown naturally in clear, cold waters.
Fun fact: In the summer and spring, the coasts of Japan glow in the dark – this is due to the luminescent shrimp, which live in the sand and become visible during low tides. The noise of snapping shrimp can disrupt submarine sonars – the hydroacoustician will hear only a continuous screen of noise.
Shrimp — something that is actively eaten, bred in aquariums, but very little is known about this strange creature that plays an important role in the ecosystem of the oceans. This is not just a delicacy or an ingredient in popular dishes, but a unique organism that surprises and delights with its features.