Sea urchin emits a cloud of venomous jaws to deter predators

By Sandhya Sekar

Species: The collector sea urchin (Tripneustes gratilla) – also called the cake or Parson’s hat sea urchin

Habitat: Coral reefs, seagrass meadows and algae forests in the tropical seas of the Indo-Pacific

The collector sea urchin looks like a pretty pincushion lying on the ocean floor, going about its business of munching on algae and seaweed.

But when threatened, this sedate pincushion has a most extraordinary defence. It releases a cloud of semiautonomous weapons: hundreds of tiny jaws that are still capable of biting and releasing venom even when separated from the sea urchin’s body.

Sea urchins have a hard, chalky shell covered in long spikes. Nestled among the spikes are tubular stalks topped with biting jaws known as pedicellariae.  One type of these appendages even has venom as well.

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