Echinoderms exhibit a remarkable diversity, yet share some unique characteristics. Over 6,500 species display a notable 5-way radial symmetry, prominently seen in starfish. Their skeletons are composed of calcium carbonate plates and spines, known as ossicles, which provide a rigid structure. These skeletons are key to the widespread preservation of echinoderm fossils, some dating back 500 million years.

Holothurians, or sea cucumbers, stand out with their retractable feeding tentacles and tube feet, which they use to forage in the seabed. They play diverse roles, including filter feeding, bioturbation, and forming symbiotic relationships with creatures like emperor shrimps and pearlfish. Defensive adaptations are also notable in holothurians.

Other echinoderms include sea urchins, which help maintain ecological balance, and starfish, with the Crown-of-thorns species highlighting ecosystem instability concerns. Brittle stars and basket stars add to the phylum's diversity.

Footage Sources: Various YouTube sources, BBC, Jonathan Bird's Blue World, MBARI, OceanX, NatGeo, Ocean Exploration Institute, and others.

Music:

• Relics by Ben Prunty (Subnautica Below Zero)
• Seductress by Francis Preve
• Dark Walk by Kevin MacLeod (Creative Commons Attribution 4.0)
• Lone Harvest by Kevin MacLeod (Creative Commons Attribution 4.0)
• Crystal Caves by Ben Prunty

Additional Resources:

• NOAA Ocean Explorer
• Ocean Conservancy Blog on Sea Pigs