Perhaps in our predatory world, far more people imagine shrimp floating in a pan than their way of moving in their natural habitat. It is well known that shrimp live in water. What are they doing there? Is it only in the salty environment that they settle? How to move in this vast space in search of food, at home and taking care of procreation? Shrimp crawl or swim?
What kind of beast is shrimp?
Shrimps are arthropod animals, decapod crustaceans, mollusks. They live in huge numbers and diversity in warm and cold seas around the world, and some species live in fresh waters, and some even in aquariums.
Only in the Russian seas in the Far East, there are more than one hundred species of shrimp.
Shrimp scavengers, predators, cleaners and orderlies, both in nature and in the aquarium. However, they are mostly not aggressive (there are exceptions). They are capable not only of peaceful neighborhood, but even of symbiosis (mutually beneficial coexistence is practiced by some varieties). They rarely allow cannibalism; living relatives will be eaten only under especially stressful situations or driven by an overly strong feeling of hunger.
They publish and perceive ultrasound.
They have optic-superpositional facet organs of vision - the eyes consist of many hexagonal segments - ommatidia. They perceive the image without details, but they can catch quick flickering (this ability is ten times higher than human) and ultraviolet radiation, which helps to better navigate in space.
Gills are used for breathing.
They lead a very active lifestyle - they move a lot.
All modes of transportation
Shrimp legs are a large part of the functional parts of the body - several pairs have changed during the evolution, and some have remained walking and swimming. So in fresh water or in the sea, shrimp both swim and crawl.
Many organs formed from their legs: genital (the first abdominal pair in males), partially digestive (they also play the role of a weapon) - 3 chest pairs of maxilla.
The remaining five pectorals are walking legs.
The abdominal 5 pairs are called pleopods. They work as oars, help the shrimp swim, and function as females in the corresponding period.
Given the number of shrimp movements along the bottom, all kinds of plants and the water column in the process of life, it is not surprising that the organs of movement reached maximum efficiency in the process of formation of these animals.
How do prawns swim
Shrimps are rowed with abdominal oar legs, but not at the same time, but using pairs in turn, from back to front. It turns out a wave-like movement of pleopods with an interval of a quarter cycle between the activation of each pair of legs.
Features of the movement of shrimp in water attracted the attention of scientists. And not only zoologists. A special group consisting of only one biologist and four mathematicians, using computer simulation, calculated the effectiveness of a peculiar way of swimming crustaceans in comparison with some others, which body structure allows shrimps to use.
It turned out that the way shrimps swim is as effective as possible.
If they rowed with all their legs at the same time, the efficiency would be one third lower than the available method, and if the wave-like movement of the legs went from head to tail, then three times.
To implement such a complex scheme, shrimps have two nerve cells to control the movement of each pleopod - one makes the leg push, the other returns the limb back.
With the next pair of “oars”, these neurons have a neural connection that provides exactly that quarter-cycle rhythm, which makes swimming of such arthropods most effective.
Features and differences
Shrimps are among the few arthropods changing their shells - they practice molting. Moreover, the female usually changes clothes before mating.
During molting, limbs that have been damaged or lost are restored - in young people it is faster, in older adults it can take several links.
Freedom-loving shrimp that live in cold waters are not susceptible to artificial reproduction. They live and breed only in their natural habitat.
They have eyesight, smell, touch and "chemical feeling".
Some species can change sex throughout life - a feature called "protandric hermaphroditism."
Certain species are also able to perceive infrared rays. For example, a mantis shrimp sees four times as many flowers as a human.
Special among special
All the same shrimp or mantis shrimp is distinguished by complete fearlessness and frantic temperament at 10 centimeters in length. Not only does he behave as he wants, attacking everything around, beating with claws at a speed of about 80 km / h and a force of 2.5 thousand times the weight of the mollusk itself, it also creates a shock wave of high temperature. Simply, it blows up those who come in the way.
Mantis shrimp can breed offspring in pairs or separate children and disperse.
Incredibly beautiful - they have a bright, multi-colored, sometimes luminous color.
Very dangerous. Called "finger blasters" and "killer shrimp." To get to know them and see how shrimps swim, it is better not to go under the water - it is much safer to evaluate this sight when watching a video.