Forcipulatida

Forcipulatida is an order of starfish belonging to the class Asteroidea. They are commonly known as brittle stars or serpent stars due to their slender, flexible arms and tendency to readily detach their arms as a defense mechanism. They are abundant in marine environments around the globe, particularly in shallow waters and on the deep seafloor.

Characteristics

Forcipulatida are characterized by several distinct features that set them apart from other starfish orders:

  • Slender, flexible arms: The most prominent feature of Forcipulatida is their long, thin, and flexible arms, which are often much longer than the central disc of the body. This gives them a serpentine appearance, allowing them to move through crevices and over uneven terrain with ease.
  • Fragile arms: The arms are easily detached at specific points known as autotomy zones as a defense mechanism against predators. This allows the brittle star to escape while the detached arm wriggles and distracts the predator. The arm can regenerate later.
  • Forcipules: Forcipulatida possess tiny, pincer-like structures called forcipules along the sides of their arms. These forcipules are used for defense, feeding, and grooming.
  • Reduced spines: Compared to other starfish orders, Forcipulatida have relatively few and small spines, which are often concealed within the forcipules.

Environments

Forcipulatida are found in a wide variety of marine environments, from shallow coastal waters to the deep seafloor. They are particularly abundant in areas with soft sediments such as sand, mud, and gravel, where they can burrow and forage for food. They are also found in coral reefs, kelp forests, and other habitats with complex structures that provide shelter and foraging opportunities.

Diet and Feeding

Forcipulatida are mostly scavengers and detritivores, feeding on decaying organic matter, algae, and small invertebrates. Some species are carnivores, capturing and consuming small crustaceans and worms. Their feeding method is diverse, with some species using their arms to sweep food towards their mouths, while others use their forcipules to grasp prey.

Reproduction

Forcipulatida reproduce sexually, with external fertilization. The female releases eggs into the water, and the male releases sperm to fertilize them. Some species brood their eggs, holding them attached to the underside of their central disc until they hatch. The larvae are planktonic, drifting in the water column until they metamorphose into juvenile brittle stars.

References

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