Echinoderms: what are they, characteristics, classification and examples

Echinoderms (phylum Echinodermata) are part of the vast and diverse kingdom of animals . Currently they have the presence of about 7,000 species , although, throughout the history of the evolution of the Earth’s biodiversity, echinoderms had more than 20,000 species of animals, so that 13,000 of them became extinct .

Known by some groups of very characteristic and striking animals of the ocean floor, such as stars and sea urchins, the great biodiversity that echinoderms harbor makes them one of the phyla most studied by zoologists and, without a doubt, the most admired by all nature lovers.

In the next sections of this article we will detail information about the multiple characteristics that best define echinoderms, as well as the classification and some examples of their most representative groups and species.

These are, in summary, the main characteristics of echinoderms :

Anatomy of echinoderms

The most outstanding characteristics of echinoderms are, without a doubt, that they are invertebrate animals , the presence of an external skeleton of calcareous origin, their peculiar pentaradiate symmetry (unique case within the Animalia kingdom) and the spines they have on their skin, For which they receive their scientific name: echino (thorn) and dermos (skin).

Where do echinoderms live

The different species that make up the edge of the echinoderms find their natural habitat in the marine and benthic ecosystems (of the deep sea), throughout the different seas and oceans of the planet. Learn everything about the marine ecosystem: what it is, characteristics, flora and fauna .

Feeding of echinoderms

Regarding what echinoderms eat, it is worth highlighting the different strategies and eating habits (mainly opportunistic) that the different groups of the phylum have, among which the projection of an everted stomach with mucus stands out in the species of starfish (class Asteroidea) and the zoo and phytoplankton filter feeding of sea lilies (Crinoidea class).

Echinoderm respiration

Gaseous exchange is carried out in most echinoderms from a complex aquifer vascular system, based on the action of a plate that acts as an orifice (madreporite) and the intervention of numerous conduits that allow efficient transport of the Aqueous liquid that contains the proteins and nutrients necessary for the survival of the animal.

Reproduction of echinoderms

The complex life cycles of echinoderms allow them to be able to choose between one reproductive method or another, sometimes choosing external sexual reproduction (with exchange of genetic material with another organism of the opposite sex of the same species), or on the contrary asexual reproduction (without genetic exchange or the need for another individual to reproduce). In the latter case, the curious process of physiparity stands out by means of which some species of echinoderms can divide their body into two halves (from spontaneous fission), each of which will be able to regenerate the rest of its organism by itself herself.

To know the different types of echinoderms that we can find in marine ecosystems around the world, we must resort to the taxonomic classification that orders and differentiates them according to their most outstanding anatomical and functional characteristics. In this way, the current classification of echinoderms differentiates the following classes:

• Asteroidea (starfish). In this other AgroCorrn article you can learn everything about the Starfish: characteristic, reproduction and taxonomy .
• Crinoidea (sea lilies / feathered starfish).
• Echinoidea (sea urchins).
• Holothuroidea (holothurians / sea cucumbers).
• Ophiuroidea (starfish or serpent stars).

In the next section we will put some examples of species that belong to these classes of echinoderms to get to know them more closely.

This edge of the animal kingdom plays a very important role in balancing the marine ecosystems in which they are found. Despite having suffered the extinction of many of the species that were part of the Echinodermata phylum, current species struggle daily to maintain their position within the evolutionary chain, depending on many occasions on environmental conditions and habitat characteristics, in order to balance. its population levels and the correct functioning of its ecological niche. For all these reasons, human beings must be aware of the importance of echinoderms., respect their lives and habitats and not participate in any type of anthropic activity that puts the integrity of the echinoderms at risk (such as scuba diving, snorkeling and other aquatic activities in which we interact with these precious marine animals, as they can be done without arriving to annoy them, just watch them). Here are some examples of echinoderm species :

• Estrella Espinosa Rojas ( Echinaater dissolved )
• Starfish ( Protoreaster linckii )
• New Zealand Starfish ( Coscinasterias calamaria )
• Comet star ( Linckia guildingii )
• Fire urchins ( Asthenosoma intermedium )
• Hawaii Hedgehog ( Heterocentrotus mammillatus )
• Mexican Erizo ( Diadema mexicanum )
• Puercoespín Marino ( Centrostephanus )
• Holoturia negra (Holothuria leucospilota)
• Holothuria persiculida (Hansenothuria benti)
• Holothuria cinerascens
• Elegant Feather Star ( T ropiometra carinata )
• Mediterranean carnation ( Mediterranean Antedon )
• Sand Dollar ( Mellita longifissa )
• Ofiura (Ophiopteris antipodum)

If you want to read more articles similar to Echinoderms: what they are, characteristics, classification and examples , we recommend that you enter our Biodiversity category .