Echinoderms are exclusively bottom-dwelling marine animals, that is to say that they are benthic animals (with very few exceptions). Their body has a radial symmetry in which the body is divided into five regions around a central disc. Another characteristic of this group of species, is the presence of calcareous ossicles that are part of its skeleton. Currently there are more than 7,000 species of Echinoderms described, which we will find in all oceans and seas regardless of the depth. Moreover, in the abyssal plains they are the most frequent animal group, and they can represent 95% of the biomass of the abyssal ecosystem.
Echinoderms are a group of great importance both at an ecological, biological and geological level. At an ecological level, there is no other group of animals so abundant in the biotic deserts of the abyssal plains, as previously mentioned. Echinoderms are animals with a great capacity of tissue regeneration, in some cases an individual can completely regenerate from one of the five regions of its body. Therefore, this capacity of regeneration is a characteristic of great interest for biology, and many species of Echinoderms have been used in regenerative studies. Geologically, the importance of Echinoderms is determined by their calcareous skeletons, as well as by their great abundance. This has made Echinoderms one of the main contributors to limestone deposit formations.
In relation to the reproduction of Echinoderms, their reproduction is mainly sexual and external, although there are species with asexual reproduction by fission of the specimen.