Echinoderms: The Ultimate Animal


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Echinoderms are slow animals radically different from us, but they are an evolutionary success. All echinoderms have five-part symmetry. We see the inner workings of sea stars, from their tube feet to their skeleton.

Urchins are ferocious herbivores chomping down kelp with their jaws. Cucumbers vacuum clean food from the sediment with their tube feet having a big affect on sea floor ecology. Brittle stars blanket some areas of the ocean bottom catching drifting plankton.

Echinoderms pump water into their tube feet, giving them power to move. They have light-sensing organs and can smell their way to food. Sea stars are formidable predators. We see their tube feet pry open a mussel and extrude the stomach into the mussel. A camera inside the mussel shows us actual footage of the stomach digesting the mussel. We also see the formidable many armed sun star chase and catch a snail.

Next Generation Science Standards for this Video

The structure of the echinoderm body plan is based on five-part symmetry with no head to lead the way. Their bodies seem little more than a skeleton made of tiny little plates and water. They move on hundreds of tiny, water-filled tube feet operated by a hydraulic system. This works well for slow moving, bottom dwelling animals and their tube feet are very efficient at catching prey.

The body plan animation visualizes the complex echinoderm structures and how they function:

  • Five-part symmetry
  • Internal skeleton make of small plates
  • Fluid filled system that hydraulically operates tube feet