Arbaciidae

Arbaciidae is a family of sea urchins in the order Arbaciida. It includes about 30 species found in various habitats, ranging from shallow intertidal zones to deep-sea environments. These sea urchins are characterized by their globose or flattened tests (shells), often with prominent spines. Arbaciidae are known for their diverse feeding habits, including herbivory, detritivory, and predation on smaller invertebrates.

Black Sea Urchin – Arbacia lixula

Common Names

Common names for sea urchins in the Arbaciidae family include:

  • Sea urchins
  • Purple sea urchins
  • Slate pencil urchins
  • Heart urchins

Characteristics

Arbaciidae sea urchins share several distinctive features, including:

  • Globose or flattened tests: The shell, or test, is typically round or slightly flattened.
  • Prominent spines: These spines are often long, sharp, and sometimes brightly colored.
  • Five-part symmetry: Like all echinoderms, Arbaciidae have radial symmetry with five sections.
  • Tube feet: These are small, sucker-like appendages used for locomotion and feeding.
  • Aristotle's lantern: This is a complex jaw apparatus located within the mouth, used for scraping algae or other food sources.

Environments

Arbaciidae species are found in various marine habitats, including:

  • Intertidal zones: These are the areas between high and low tides.
  • Subtidal zones: Areas below the low tide mark.
  • Coral reefs: Some species inhabit these diverse ecosystems.
  • Deep-sea environments: Certain Arbaciidae species have adapted to live in the depths of the ocean.

References

For further information on Arbaciidae, you can refer to the following sources: