Sea urchins are the inhabitants of the oceans. These representatives of ichthyofauna can be dangerous to humans. At the same time, they are of great benefit. Read about the types of these animals, their appearance, reproduction and nutrition in this article.
Kinds
The class of these echinoderms is very numerous. Therefore, the animals related to it are conditionally divided into two subclasses. The first group is regular hedgehogs, that is, those whose body shape is spherical. The body of irregular echinoderms is more like a stretched disk.
There are over 900 species of animals, some of which are very common. These include:
- Black sea urchins that possess long needles. This animal is a great danger to humans, as it has long needles. An interesting fact is that the beauty of a black hedgehog can quickly turn into his weapon: for any sign of danger, he directs the needle towards the stimulus. That is, the shadow of an object falling on it can be regarded as an attack.
- A round sea urchin, which can also be dangerous to humans. It belongs to one of the most common species.
- Japanese sea urchin. By the name it’s clear where he lives. This echinoderm representative can attack a person if he feels the danger emanating from him.
- Slate sea urchin, which is characterized by amazing red color. His needles have an unusual triangle shape with a blunt apex. According to one version, it got its name due to the fact that in ancient times with the help of his needles they wrote on slate boards.
- A species like a diadem is very dangerous for humans. At the slightest sign of danger, the animal pierces the skin of the victim with brittle needles, and they break. The process of extracting them is very painful. Often this species is found near the Turkish coasts that tourists like.
Description
The animals referred to in this article belong to a class such as echinoderms. Most often, sea urchins have a spherical body, the diameter of which is from 2 to 30 cm together with needles. On the one hand, it is wrinkled, since there is a mouth opening. Moreover, it is this part of their body that serves as a means of transportation, because with its help animals move along the seabed. The skeleton of these echinoderms is very well developed, it is soft only near the mouth and anus located on the back. With the help of numerous tubercles covering the surface of the body, needles are attached to it.
The sea urchin, the description of which is presented in this article, can have almost any color. Some species have the unique ability to adjust body color to the surrounding space.
Needles
Lime sticks are cylindrical. They are movably attached to the body, which allows them to quietly rotate in different directions. They not only protect animals, but also help them move around. Moreover, some of them have a grasping function. In this case, it is customary to call these organs pedicellaria.
Some needles contain poisonous glands that secrete a fairly strong substance. Since such organs are shorter than the rest, ordinary needles move apart, releasing them out. Because of the poison for humans, about 80 species of these animals are dangerous. The length of the needles can reach 30 cm in length.
Poison
Sea urchins can fatally poison a person. How does this happen? As soon as the animal feels that it is in danger, it closes its needle-tweezers on the victim’s body and injects poison under the skin. It is a whitish liquid.
Places that have been punctured begin to itch. A person feels a strong burning sensation, his skin acquires a pronounced red tint, swelling may form. All this is accompanied by pain. In severe cases, there is a loss of sensitivity, paralysis can break the victim. The poison, released by tweezers, affects the nervous system. Under his influence, breathing is disturbed, and this can be very dangerous for divers.
If you do not get out on land in time and do not help a person, he may die. Indeed, documented cases where a person affected by poison did not have time to rise to the surface and died. At best, the pain will go away in 20 minutes. In less than a week, other signs of poisoning will disappear. However, the paralysis effect lasts for 6 hours.
To save the life of the victim, it is necessary to limit his mobility, remove the remaining needles from the wounds and go to the hospital as soon as possible.
Habitat
All species of sea urchins live in waters that are of medium or high salinity. For example, the range of black hedgehogs is represented by open spaces from Japan and China to East Africa. They can also be found near the Hawaiian Islands. The round hedgehog, as well as other representatives of the echinoderm class, have a similar range. These animals are not found in the slightly salted waters of the Black and Caspian Seas.
A favorite habitat for echinoderms is the seabed. They move along it with the help of ambulacral legs. These organs are long processes, at the end of which suction cups are located. They allow animals to move along vertical surfaces.
Nutrition
It's time to find out what the sea urchin eats. It all depends on which subclass of echinoderms it belongs to. Wrong hedgehogs eat plankton. But the diet of their regular relatives is more diverse. So, these predatory animals are capable of hunting crustaceans and mollusks. At the same time, they can eat algae and even carrion. Often they attack other hedgehogs, which are smaller, and also attack starfish.
Breeding
To understand how sea urchins breed, you need to know a few facts about them. So, these animals are dioecious, that is, among them there are both female and male individuals. Fertilization is external. This means that the male fertilizes the eggs laid by the female. This occurs in shallow water. However, those species that live in Antarctic waters are viviparous. A special brood chamber is located in the female’s body, in which the eggs develop.
Reproduction of sea urchins is a fairly simple process that most often occurs outside the body of a female. However, those individuals that were born in the waters of the Antarctic leave the maternal body fully formed. Three years later, their puberty begins. In total, the life expectancy of these echinoderms is from 12 to 15 years. Documents have been documented when scientists were able to find individuals whose age reached 35 years. Therefore, they are conditionally considered long-livers.
Enemies
Despite the fact that sea urchins have good self-defense, they often become food for other birds, fish and mammals. For the otter, these echinoderms are a special delicacy. The animal catches a thorny ball, and then throws it onto a hard surface several times and breaks the carapace. Seabirds prey on hedgehogs in a similar way. So, large birds raise their prey to a great height and throw barbed food onto stones. The carapace breaks, and the meat of the animal remains unprotected.
Benefit
The sea urchin, the photo of which is presented in this article, is very appreciated. Firstly, caviar of such species as fawn, multi-needle and green is very popular. According to the beliefs of the Japanese, this product is able to prolong youth and give a person longevity. Indeed, caviar contains nutrients, essential amino acids and fats. Recently, studies have been conducted, as a result of which scientists have found that the human and sea urchin genomes partially overlap. That is why long-living animals can maintain the lifespan of a rational person. It will be most useful to eat fresh caviar, which was not subjected to heat treatment. Not everyone likes it in its pure form, but gives salads and other dishes an interesting taste.
Secondly, with the help of these animals it is possible to catch commercial fish. The fact is that echinoderms gather in large groups during the spawning season. They attract fish and crustaceans who do not mind eating sea urchins. And fishermen at this time catch, for example, flounder.