Leptasterias aequalis (Stimpson 1862)

How to Distinguish from Similar Species: Species of Leptasterias are very hard to tell apart, and L. aequalis is probably a species complex. This species is very similar to Leptasterias pusilla but can be distinguished by its large, flat aboral spines, thicker arms, and darker color. L. hexactis is usually olive-green or indigo, and its pedicellariae are embedded in tissue at the base or midway up the aboral spines. L. epichlora is usually mottled and blue-gray, dark green, or indigo and its pedicellariae are few and randomly arranged around the aboral spines.

Common on rocky shores that are exposed to the surf.

Geographical Range: L. aequalis ranges from Vancouver Island, southern BC. Canada to Santa Catalina Island in the Channel Islands, southern CA.

Depth Range: Intertidal zone under rocks or algae.

This species generally has six rays and an arm radius to 5.2 cm. The color of the aboral surface is extremely variable, from olive-green, indigo or gray to coral-red or orange and usually mottled. The arms appear relatively broad and heavy when the animal is moving, and the aboral spines are flattened and mushroom-shaped. Pedicellariae on the aboral surface are numerous and randomly arranged around the aboral spines.

Biology/Natural History: L. aequalis is known to cling very tightly to rocks and it has the ability to conform closely to irregularities in the surface. It is a carnivore and feeds on sea cucumbers, littorine snails, limpets, chitons, small mussels, barnacles, and other small animals, including dead animals. L. aequalis often selects large, hard to capture prey that is often rich in calories. This type of prey supplies most of the sea star’s energy. It is often in direct competition with the much larger sea star, Pisaster ochraceus for food. Breeding occurs from November to April in the Puget Sound. The eggs are yellow, yolky, and about 0.9 mm in diameter. A unique feature of this species is that the broods of eggs are held by the female in the region of the mouth below the central disk. Because of this, brooding females cannot flatten themselves against the substratum and are only anchored by their outermost tube feet. Unfortunately, they are often dislodged by the waves, losing their eggs. It is necessary for the female to clean the egg masses, and if she does not do this then the eggs quickly die. The presence of the eggs blocks the female’s mouth and she will not feed while brooding, even if there is food readily available. The development of the embryos is direct and individuals reach maturity within 2 years.

Leptasterias aequalis, common names little six-rayed seastar or six-armed star, is a species of starfish.

This is a small species, with a total width of only about 5 centimetres (2.0 in). The coloration is extremely variable.

This seastar is found in the eastern Pacific Ocean, from Washington to Southern California. It lives on rocky shores, in the mid-intertidal zone.

Many sea-stars broadcast-spawn their embryos, where fertilization occurs in the water column; however, Leptasterias species brood their embryos locally. The stars form mating aggregations and the female sits on her brood for a period of 6–8 weeks while the embryos develop underneath. Eventually, the embryos fully metamorphose into juvenile sea-stars and walk away, and thus can only locally disperse. Larger females produce larger embryos of great quality; however, as larger broods are produced, a considerable proportion of them are lost.