The Fat Henricia star is found in the north Pacific ocean, they are very common in the Pacific Northwest. They can be seen on the beach, under rocks, in tidal pools or on gravel. Its aquatic range is the coastal and subtidal zones. They are almost always found near sponges and coral because of the currents they create, making it easier for the sea star to filter feed. They can be found from depths of 0 to more than 2000 meters.
They feed upon detritus and plankton floating in the water and uses currents made by sponges or coral to make this process easier. Henricia feeds on plankton, sponge tissue, ascidians, and other invertebrates. It is in turn, eaten by other vertebrates.
It has five slender legs that taper evenly to tips that are connected by a central disc. They can grow up to 20 cm. The sides of the legs are curving and smooth. The legs contain many of its organs. On the tips of the rays are the eyespots. These are darkly pigmented organs that sense the presence of light. The legs also contain parts of the stomach, nervous system, and most other organs.
Like all other sea stars, they use water instead of blood. They pump filtered seawater in and out of their body. This seawater is transported through a vascular tube system and delivers nutrients to the different organs.
Fat Henricia Stars are also one of the only species of sea stars that broods its eggs. The female stays with the eggs while they hatch, and continues to stay with them as larvae. The larvae stay in a dome shape created by the female’s arms until they are ready to go into the ocean on their own.