Echinoderms have a dermatoskeleton.
Echinoderms are marine metazoan animals that have a dermatoskeleton with scattered calcareous granules or juxtaposed calcareous plates. Sometimes, these plates have spines. On the other hand, echinoderms ( Echinodermata ) are characterized by their pentagonal radiating symmetry : they have a body with five regions around a central disk.
The dermatoskeleton has small holes from which appendages emerge that can end in suction cups. These appendices are organized in radial series. Echinoids and asteroids also have pedicellariae , which are pincer -shaped structures to eliminate larvae that try to adhere to the body, attack prey or defend themselves from predators.
Specialists affirm that there are about 7,000 species of echinoderms today, in addition to another 13,000 that are already extinct. They all live in the marine environment and are incapable of subsisting in fresh water or on land .
Characteristics of echinoderms
Among the particularities of echinoderms, it is worth noting that they lack a heart , since the circulatory system is open and the blood vessels are in connection with sinuses or lacunae. Echinoderms also do not have developed excretory organs; On the contrary, the substances are eliminated through the aquifer vascular system .
Regarding their mobility capacity, most echinoderms can crawl and swim thanks to the movement of their arms. Mobility is usually slow and smooth.
It can be mentioned, on the other hand, that its reproduction is sexual . However, some species can reproduce asexually through one of their arms. This is possible only when the arm contains a part of the central disk.
Sea urchins are echinoderms.
Some species of the group
Among the numerous species that exist within this group, the following are some of the best known and studied.
- The starfish , which can have four, five, six or more limbs which help it move through the water. It has the great characteristic of regenerating those fragments of its body that it may lose .
- The sea urchin is one of the species cataloged within the phylum Echinodermata, in which those animals with spiny skin are located. It has a round body that is full of spines (like the land hedgehog); They can measure up to 20 cm depending on the species and can be extremely harmful against their attackers. On the lower surface, the hedgehog has a mouth and on the upper surface, the anus. It feeds on algae, which it extracts from rocks using its jaw system.
- The ophiura is one of the most unique echinoderms, since it feeds on other animals. It has five long, extremely thin arms with thorns that serve to capture its victims. Its main food source is certain mollusks , small crustaceans and other small animals. They also have the ability to regenerate those parts of the body that they may lose.
- The flamingo tongue , scientifically called holoturia , belongs to those thousands of marine animals that live thanks to the microhabitats created around coral reefs.
- The crown-of-thorns star poses a danger to marine reefs since it feeds on coral and an overpopulation of this species endangers the survival of the microhabitat . They have a mouth covered with radial arms, where each one has a row of ambiulacral feet that allow it to move from one place to another easily.
- The brown sea cucumber is evolutionarily related to the starfish , sea urchin and sea lilies. These animals feed on planktonic organisms and to catch them they use their tentacles, which are surrounded by mucus for this purpose.