Diadematoida
Diadematoida is an order of sea urchins belonging to the class Echinoidea. This order comprises about 300 species found in various habitats, primarily in tropical and subtropical waters worldwide.
Common Names
Diadematoid sea urchins are commonly referred to as long-spined sea urchins due to their distinctive long, sharp spines. They are also known as diadems, pencil urchins, and crown-of-thorns starfish.
Characteristics
Diadematoid sea urchins possess a number of defining characteristics:
- Long, sharp spines: This is the most prominent feature, offering protection from predators and aiding in locomotion.
- Five-part radial symmetry: Like all echinoderms, they exhibit a pentameral body plan.
- Test: Their rigid, calcareous shell (test) is covered with spines and pedicellariae (small pincer-like structures).
- Tube feet: They have numerous tube feet, which are used for movement, feeding, and respiration.
- Aristotle's lantern: This complex jaw structure is used for scraping algae and other food from surfaces.
Environments
Diadematoid sea urchins inhabit a range of marine environments, including:
- Coral reefs: Many species thrive in coral reef ecosystems, playing an important role in maintaining coral health.
- Rocky shores: They can be found in intertidal zones and on rocky substrates.
- Seagrass beds: Some species graze on seagrass, contributing to the diversity of these habitats.
- Deep sea: Certain diadematoid species inhabit deep-sea environments.
References
For further information and resources on Diadematoida, refer to the following websites:
- World Register of Marine Species: https://www.marinespecies.org/aphia.php?p=taxdetails&id=1242
- Encyclopedia of Life: https://eol.org/pages/3334457/overview
- IUCN Red List: https://www.iucnredlist.org/search?query=Diadematoida