echinoderm

noun

echi·​no·​derm i-ˈkī-nə-ˌdərm 

: any of a phylum (Echinodermata) of radially symmetrical coelomate marine animals including the starfishes, sea urchins, and related forms

echinodermatous

i-ˌkī-nə-ˈdər-mə-təs 

adjective

Examples of echinoderm in a Sentence

Recent Examples on the Web

All echinoderms, including starfish, start their lives as bilaterally symmetrical larvae. —Jack Knudson, Discover Magazine, 26 June 2025

But some of the massive, velvety echinoderms began the spawning process spontaneously — three days before the group would arrive. —Lila Seidman, Los Angeles Times, 11 Apr. 2025

Like all echinoderms, starfish have endoskeletons built of tiny bones, or ossicles, linked by muscles and collagen fibers that allow the animals to change posture and move. —Elizabeth Rayne, Ars Technica, 14 Sep. 2024

In fact, most aquatic invertebrates and all echinoderms (sea stars, sea urchins, sea cucumbers, and sand dollars) start life as planktonic larvae before growing into the adult form we’re used to seeing. —Jennifer Adler, Vox, 7 July 2024

Word History

Etymology

borrowed from French échinoderme, borrowed from New Latin Echinoderma, taken as singular of Echinodermata, from echino- echino- + -dermata, neuter plural of -dermatos -dermatous

Note: Echinodermata was a pre-Linnaean taxon that comprised animals of the present-day class Echinoidea. The name Echinodermata, "those having hedgehog-like skin," was coined by the German jurist and naturalist Jacob Theodor Klein (1685-1759) in Naturalis dispositio Echinodermatum (Danzig, 1734).

First Known Use

1835, in the meaning defined above

Rhymes for echinoderm

• angiosperm
• affirm
• bookworm
• confirm
• cutworm
• earthworm
• infirm
• midterm
• tapeworm
• wireworm
• berm
• ferm

Kids Definition

echinoderm

noun

echi·​no·​derm i-ˈkī-nə-ˌdərm 

: any of a phylum of marine invertebrate animals (as starfishes, sea urchins, and sea cucumbers) that have a number of similar body parts (as the arms of a starfish) arranged around a central axis, a calcium-containing inner skeleton, and a water-vascular system