Humans are part of the phylum Chordata, meaning that they have vertebrae. This is the phylum that most people are familiar with, but the animal kingdom has many more groups of classification. Those that live in the ocean are even more unique, contributing different phyla to the classification system. For example, some marine animals are classified in the phylum Echinodermata.
Echinodermata directly translates to “rough or spiny skin”. Marine echinoderms include creatures such as starfish, sea cucumbers, and sea lilies. These echinoderms are characterized by their rough skin, calcium carbonate skeleton, and radial or elongated body forms. Sea stars exhibit radial symmetry with the center of their nervous system placed at the middle and stretching out along the arms. If any portion of the sea star is disconnected or lost, the body can regenerate as long as the central portion of the body is intact. Sea cucumbers exhibit an elongated body type, symmetrical along their cylindrical form. No echinoderms have a heart, brain, or eyes, however, nerves and unique structures making them up and helping them survive.
Another unique characteristic of echinoderms is their water vascular system, involved in their hydraulic processes. Sea stars, for example, pump water along their entire bodies and through their arms, extending all the way into little tube feet covering the bottoms of the arms called podia. These podia, when connected to the water vascular system and filled with water, are able to move and convey the starfish across the seafloor. Without the water vascular system, echinoderms are not able to move or function properly. The system uses water to contract and relax different body parts, much like muscles.
From their symmetrical body forms to their water vascular systems, echinoderms have truly amazing adaptations to stay resilient and survive in the wild. Very different from humans, echinoderms appear to many as the aliens of the sea.
