Centrocidaris is a genus of deep-sea cidaroid sea urchins belonging to the family Cidaridae. These marine invertebrates are characterized by their robust primary spines, which are often thick and club-shaped, leading to their common designation as "pencil urchins" or "slate-pencil urchins" in a broader cidaroid context. The genus was first described by Alexander Agassiz in 1879.
Classification
- Kingdom: Animalia
- Phylum: Echinodermata
- Class: Echinoidea
- Order: Cidaroida
- Family: Cidaridae
- Genus: Centrocidaris A. Agassiz, 1879
Description
Centrocidaris species share several distinguishing features typical of the Cidaridae family, along with specific generic characteristics:
- Test: The test (shell) is generally robust, globose to slightly flattened, and composed of large, thick plates.
- Primary Spines: The most prominent feature. These spines are typically very thick, heavy, and robust, often appearing cylindrical, slightly flattened, or club-shaped. Their surfaces can be smooth, granular, or sculptured. They are often long relative to the test diameter. They attach to large tubercles on the interambulacral plates via a ball-and-socket joint, allowing for movement.
- Secondary Spines: These are much smaller, flattened, and scale-like, covering the surface of the test between the primary spines, providing protection and helping to keep the test clean.
- Ambulacra and Interambulacra: The ambulacral (food groove) and interambulacral (plates between food grooves) areas are arranged in distinct columns. The ambulacral plates bear pores for tube feet.
- Apical System: The apical system (the top central area of the test where the madreporite and gonopores are located) is relatively small and typically dicyclic (with ocular plates separated from the periproct by genital plates).
- Peristome: The mouth opening on the underside (peristome) is relatively large.
Habitat and Distribution
Species within the genus Centrocidaris are exclusively deep-sea organisms. They are found in the bathyal and abyssal zones of various oceans, including the Pacific, Atlantic, and Indian Oceans, typically at depths ranging from several hundred to over a thousand meters. Their deep-water habitat makes them less frequently observed compared to shallow-water urchins.
Ecology
Like other cidaroid sea urchins, Centrocidaris species are likely detritivores or grazers, feeding on organic matter, algae, and small invertebrates found on the seafloor. Their robust spines may offer protection against predators in the deep-sea environment.
Selected Species
Some recognized species within the genus Centrocidaris include:
- Centrocidaris doederleini (A. Agassiz, 1898)
- Centrocidaris spinosa Mortensen, 1927
- Centrocidaris subspinosa Mortensen, 1903