keyhole urchin

The 'keyhole urchin' is a type of sea urchin known for its distinctive keyhole-shaped openings and its resemblance to sand dollars.

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Definition

C1Marine Biology

(technical)A flat sea urchin with keyhole-shaped openings in its shell, belonging to genera like Melitta, Rotula, and Encope.

Example

  • The keyhole urchin can often be found burrowing in sandy or muddy ocean floors.
  • Scientists study keyhole urchins to understand their unique respiratory system.