How Do Echinoderms Make Us Curious?

Echinoderms spark our curiosity through a combination of alien-like anatomy, unexpected evolutionary relationships, and near-superhuman survival abilities.

They encompass all marine creatures, including the starfish, brittle stars, sea-urchins, sea-cucumbers, and feather-stars. Echinoderms represent the largest phylum that lacks freshwater or terrestrial representatives.

Echinoderms, which are invertebrate animals with spiny skins, lack a centralized brain or heart. Instead, they use a decentralized nerve net to navigate the ocean and pump seawater through their bodies instead of blood.

Echinoderms possess a curious arrangement of tubes projecting through their skins. These tubes, called tube feet, connect to a series of water-filled canals within the animal’s body.

The muscles within the echinoderm’s body enable water pressure to exert on the tube feet, causing them to move and allowing the animal to crawl about. This hydraulic system allows them to walk, climb vertical rocks, grip objects and pry open stubborn clam shells.

They can regrow missing body parts. If a predator causes a starfish to lose an arm, the starfish can completely regenerate it. In some species, a single severed arm can grow an entirely new body.

Despite looking like aliens, scientists classify echinoderms as deuterostomes. This means that during early embryonic development, they develop similarly to vertebrates. Genetically, researchers find that they are more closely related to humans than to bugs, jellyfish, or crabs.

Many echinoderms produce “catch collagen,” a type of tissue that can change from stiff to rubbery in seconds under nervous system control. Sea cucumbers can use this ability to essentially liquefy their bodies to squeeze into tight rock crevices and then harden again to lock themselves in place.

Content for this question contributed by Beth Geigel, resident of Upper St. Clair, southern Allegheny County, Pennsylvania, USA