Echinoderms are a phylum of exclusively marine deuterostome invertebrates characterized by pentaradial symmetry in adults, a calcareous endoskeleton composed of ossicles, and a unique water vascular system that operates tube feet for locomotion, feeding, and gas exchange. Major classes include Asteroidea (sea stars), Echinoidea (sea urchins, sand dollars), Holothuroidea (sea cucumbers), Ophiuroidea (brittle stars), and Crinoidea (feather stars). They exhibit mutable collagenous tissues enabling rapid changes in body stiffness, and possess high regenerative capacity. Echinoderms are key model systems in developmental and evolutionary biology, particularly for studying deuterostome embryogenesis and larval–adult body plan transitions.
Sea cucumbers spend their lives prowling the ocean floor, scavenging for food and generally minding their own business. We can see snails leading similar lives, slimy but not bothering anyone.
Plants & Animals
Jun 18, 2025
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Sea cucumbers are the ocean's janitors, cleaning the seabed and recycling nutrients back into the water. But this humble marine invertebrate could also hold the key to stopping the spread of cancer.
Plants & Animals
Jun 10, 2025
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