Long-Armed Brittle Star

Amphiodia occidentalis exhibit pentaradial symmetry characteristic of brittle stars. They contain a flat disc body which can measure up to 11 mm in diameter that contains their organs. Five long, segmented arms at least eight times the diameter of the disc extend from the body which are covered in flattened spines and tube feet.

Additionally, they have a calcium carbonate endoskeleton composed of calcareous ossicles. Their central nervous system is highly metameric with the same pattern of peripheral nerves repeated in each arm.

Amphiodia occidentalis are facultative detritivores, mainly eating detritus on the seafloor but can feed in other ways. By using their tube feet to catch food particles, they also engage in suspension feeding.

Amphiodia occidentalis has separate sexes and are broadcast spawners, releasing their eggs and sperm into the water column where fertilization and larval development occurs as plankton Their breeding cycles are periodic with higher rates of spawning activity in the winter and spring.