Paxillosida
Paxillosida is an order of sea stars belonging to the class Asteroidea. They are commonly known as burrowing sea stars or sand stars due to their unique adaptations for a burrowing lifestyle. Paxillosida is characterized by flattened bodies with numerous small, granular ossicles (bone-like structures) and often possess a distinctive, sand-dollar-like appearance. These sea stars inhabit various marine environments, including sandy bottoms, seagrass meadows, and coral reefs, primarily in tropical and subtropical regions.
Characteristics
Paxillosida exhibits several unique characteristics that distinguish them from other sea star orders. These include:
- Flattened body: Paxillosida possess a flattened, disc-shaped body with short, blunt arms. This shape facilitates movement within soft sediments.
- Granular ossicles: The body is covered in numerous small, granular ossicles, providing protection and rigidity.
- Reduced tube feet: Paxillosida have reduced tube feet compared to other sea stars, which are often located on the ventral side. This adaptation minimizes drag during burrowing.
- Sand-dollar-like appearance: Some species have a distinctive, sand-dollar-like appearance with a circular body and a well-defined margin.
- Carnivorous diet: Paxillosida primarily feed on small invertebrates, such as worms, crustaceans, and mollusks.
Environments
Paxillosida are found in a variety of marine environments, including:
- Sandy bottoms: They are commonly found in shallow, sandy areas along coastlines.
- Seagrass meadows: Some species inhabit seagrass meadows, where they burrow among the grass blades.
- Coral reefs: Some Paxillosida species can be found in coral reef ecosystems, particularly in areas with soft sediment.
References
WoRMS - World Register of Marine Species
NCBI - National Center for Biotechnology Information