Diadema clarki is a species of sea urchin found throughout the Indo-Pacific region. It is a distinctive urchin with a black or dark-brown test (the hard outer shell) covered in long, sharp spines. Diadema clarki plays a crucial role in coral reef ecosystems, contributing to the overall health and balance of these vital environments.
Description & Characteristics
Diadema clarki is easily recognized by its large, black or dark-brown test, which can reach up to 15 cm in diameter. The test is covered in long, sharp spines that can grow up to 10 cm long. The spines are primarily black, although they may have a reddish-brown tip. The spines are brittle and easily break off if the urchin is disturbed.
This sea urchin has a distinctive, circular shape with a central opening, known as the mouth, located on the underside. The mouth is surrounded by five teeth that help the urchin to scrape algae off of surfaces. The anus is located on the opposite side of the test from the mouth.
Habitat and Occurrence
Diadema clarki is typically found in shallow, tropical waters in the Indo-Pacific region. This includes the Red Sea, the Indian Ocean, and the Pacific Ocean. Its preferred habitat is coral reefs, where it grazes on algae and helps to maintain the balance of the reef ecosystem. The species is commonly observed at depths ranging from 1 to 30 meters, although they are known to occur in depths of up to 50 meters. Diadema clarki is often found in areas with high coral cover and moderate water flow.
Taxonomy
Diadema clarki belongs to the Class: Echinoidea, which encompasses all sea urchins. It is further classified within the Order: Diadematoida, which includes sea urchins with long, sharp spines. The species belongs to the Family: Diadematidae, a family known for its distinctive long spines and often dark coloration.
Feeding
Diadema clarki is an herbivore and feeds primarily on algae, playing a crucial role in controlling algal growth on coral reefs. It uses its strong teeth and rasping tongue to scrape off algae from surfaces. This grazing activity is vital for maintaining the health of coral reefs, preventing excessive algal growth that can suffocate corals.
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