Echinoderms are a diverse group of invertebrate marine animals that include starfish, sea urchins, sand dollars, sea cucumbers, and crinoids. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates.
Acorn worms, also known as enteropneust (literally, ‘gut-breathing’) hemichordates, are marine invertebrates that share features with echinoderms and chordates. Together, these three phyla comprise ...
Echinoderm, any of a variety of invertebrate marine animals belonging to the phylum Echinodermata, characterized by a hard, spiny covering or skin. Living species include sea lilies, sea urchins, sea cucumbers, starfishes, basket stars, and sea daisies. Learn more about echinoderms.
Echinoderms are spiny-skinned invertebrates of the phylum Echinodermata, specifically recognized by the pentamerous body (five-pointed) symmetry in adults. The phylum derives its name from the Greek words ‘ekhînos,’ meaning ‘ hedgehog,’ and ‘dérma,’ meaning skin.
The conservation of genome regulatory elements over long periods of evolution is not limited to vertebrates, as previously thought, but also in echinoderms (invertebrates). This is one of the most ...
The first definitive echinoderms appeared near the start of the Cambrian. Echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the deep sea, as well as shallower oceans.
Echinoderms possess an unusual suite of appendages on their skeletons, which are used for movement, interaction, and defense. In addition to spines, urchins and sea stars both possess pedicellariae (singular pedicellaria) which are jaw-like structures often at the end of stalks.
Echinoderms are a diverse group of marine animals belonging to the phylum Echinodermata. They are characterized by a unique radial symmetry and a spiny or prickly outer skin.