Skip to primary navigation Skip to content Skip to footer
Back to Blog

Searching for an urchin and cucumber

Echinoderms are a unique group of invertebrates that includes sea stars, sand dollars, sea urchins, sea cucumbers, and more. Echinodermata is the phylum and the word breaks down to mean hedgehog-like skin. They are usually known for their radially symmetry, tubular feet, and their water vascular systems! Two echinoderms recently found on Capers island were the test of a purple sea urchin and a sea cucumber.

The purple sea urchin is known for its distinctive coloration and spiny exterior. Sporting a vibrant hue ranging from deep purple to reddish-brown, these echinoderms inhabit rocky coastal habitats, where they play a crucial role in the marine ecosystem. Despite their prickly appearance, purple sea urchins are fascinating creatures with a surprisingly delicate feeding strategy. Using their specialized mouthparts located on the underside of their body, they graze on algae and other organic matter, helping to regulate underwater plant populations and maintain ecological balance. When beach combing, usually the test of the sea urchin is discovered—this is the hard part of the urchin missing all of its spines. 

Despite their name, they are not botanical cucumbers but rather marine animals with soft, elongated bodies resembling cucumbers. If you discover one of these squishy (sometimes resembling scat!) looking critters on the beach and are wondering how are they echinoderms, here are a couple of reasons why they are grouped in that phylum. Like other echinoderms sea cucumbers have a water vascular system, and a calcareous endoskeleton composed of ossicles. In their larval stage they also have bilateral symmetry. These remarkable creatures play a vital role in marine ecosystems, serving as scavengers and recyclers, consuming organic matter and helping to maintain the health of ocean floors. With their ability to expel and regenerate their internal organs as a defense mechanism, sea cucumbers showcase remarkable adaptations!

a hand holding a sea urchin and sea cucumber.

Purple sea urchin test and sea cucumber covered in shells!

  • Posted in: