Common Seastar

Asterias forbesi is doing fine. Currently, there is no special need to save the starfish. The population is thriving without human help.

Asterias forbesi can get into mollusk beds and compete with the farmers and fishermen for food. If there is an overpopulation of sea stars, they are hard to get rid of because if they break, they will regenerate, and then there will be many more.

Another species of starfish in the genus Pisaster is a keystone predator in the rocky intertidal zone off the Pacific Coast. It maintained diversity in the tidal region by keeping the strongly competitive bivalves at a low enough population level that they could not monopolize all the resources and form a monoculture. Although not studied, it is conceivable that A. forbesi plays a similar role on the Atlantic and Gulf Coast. (Raven and Johnson 1999)

Sea stars are carnivorous and like to eat other invertebrates, marine worms, crustaceans, gastropods, sea urchins, and molluscan bivalves like mussels, clams, and oysters. A. forbesi feeds chiefly on bivalve molluscs. They grasp the mollusk and use their tube feet to suction and pull the shells apart enough to extend their stomachs out through their mouth into the mollusk. Digestion (via possible toxic juices) occurs inside the shell, turning the mollusk into liquid that is guided into the sea star's mouth by the cilia on its arms. The sea star will win in the battle against the bivalve due to muscle endurance and its ability to insert its stomach through thin openings (Amaral, 2000; Amos and Amos 1985; Bertin, 1967; Dale, 2000; Pfeffer, 1989).

Asterias forbesi are commonly found in intertidal areas and shallow waters of the Atlantic Ocean on the North American Coast from the Gulf of Maine to the Gulf of Mexico (Dale, 2000; Pfeffer, 1989).

Biogeographic Regions: atlantic ocean (Native )

Asterias forbesi is found in the littoral zones of the North American Atlantic. They may be found in abundance, but they don't form colonies. They like rocks, boulders, and oyster/clam/scallop/mussel beds. Rocks are important to help prevent washing away and oyster beds have plenty of food within range (Moore, 1997).

Aquatic Biomes: coastal

Most A. forbesi range from 7-15 cm in diameter. They are tan, brown, or olive with tomes of orange, red, or pink. Like all sea stars, A. forbesi have "spiny skin" (a thin layer of skin covering spiny ossicles) covering their skeleton. The skeleton is made of plates called ossicles and bound by connective tissue so that they move like flexible joints. The small spines are surrounded at the base by pedicellariae which are little jaws that keep the body free of debris and maybe catch a little food, too. The spines of A. forbesi are large in diameter and are an obvious feature of the external appearance. There are little tufts of skin on the surface that serve as gills. The mouth is on the ventral (oral) side and the anus is on the dorsal (aboral) side. A. forbesi along with the rest of the echinoderms are radially symmetrical. They have five arms that are capable of regenerating. The ventral sides of the sea star's arms are covered with tube feet. These tube feet have suctions at the bottom that suck in water and channel it to canals that run through the body. There is a small hard spot on the dorsal surface of the body called the madreporite or sieve plate. In A. forbesi, the madreporite is pink in colors. The madreporite has pores that allow it to filter the water before it enters the sea star's water vascular system. The madreporite feeds into the ring canal in the middle of the sea star. Attached to the ring canal are radial canals that branch off. Each radial canal runs down an arm. The radial canals are surrounded by ampullae and tube feet on each side. Ampullae are the bulbs at the top of the tube feet. (Amaral, 2000; Amos and Amos, 1985; Bertin, 1967; Dale, 2000; Fox, 1999; Raven, 1999; Vodopich, 1999).

Other Physical Features: ectothermic

Sea stars aren't highly preyed upon due to their tough, non-nutritious calcified skin. There are some kinds of crustaceans and fish that will eat them, though. A. forbesi is also known as Forbes' Sea Star and as the common sea star. It is one of the most common starfish species on the North American Atlantic coast (Dale, 2000).

Sea stars can completely regenerate as long as they have one fifth of the central disk and one arm. There is one eyespot at the end of each arm.

Sea stars in general have separate sexes. There are gonads in each arm on the ventral side. There is external fertilization because sperm and eggs are shed into the water. Females can release up to 2.5 million eggs. When one female sheds her eggs, other females in the area are stimulated to shed their eggs and then males are stimulated to shed their milt. The eggs develop into bipinnaria larvae, which lasts for about 3 weeks before settling and metamorphosing. The larvae are free-swimming and bilaterally symmetrical. They develop into sessile radial adults (Bertin, 1967; Raven, 1999).

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Woods Hole, Maine

Asterias forbesi (Desor)

Asteracanthion forbesi Desor, 1848:67.

Asterias arenicola Stimpson, 1851:268.

Asteracanthion berylinus A. Agassiz, 1863:3; 1877:94, pl. 9.

Asterias forbesi.–Verrill, 1866:345.–H. L. Clark, 1902:552, pl. 1: figs. 1, 2, pl. 4: figs. 14, 15–Fisher, 1930:205.–Gray, Downey, and Cerame-Vivas, 1968:156, fig. 34.

Asteracanthion novae boracensis Perrier, 1869:41, pl. 1: fig. 9a.

This is probably the commonest shallow-water species on the east coast of North America; certainly, it is the best known, for it is the one commonly used in biology classes. The disc is small, and the five arms are moderately long, thick, and constricted at the base. There is an irregular carinal row of plates down the middle of each arm. The superomarginal plates define the ambitus and are connected to the inferomarginals by an elongate ossicle; the inferomarginal plates are connected to 3 or 4 adambulacral plates by a triangular, unarmed ossicle. All plates from the carinals to the inferomarginals are connected by small, elongate secondary ossicles, forming an open meshwork, and bear a single, thick, upright, thorny-tipped spine, the spines of the superomarginals being slightly larger than those of the other plates. The spines are all surrounded, about halfway up, by a wreath of small, crossed pedicellariae. The inferomarginals bear two thicker, blunter spines. The small, crowded adambulacral plates bear either one or two spines, alternately; they are usually chisel shaped and often grooved. Between the spines, over the entire surface, and on many of the adambulacral spines are straight, flat, oval or cordiform pedicellariae, larger than the crossed pedicellariae which wreath the spines. The papulae between the plates are small and numerous.

The long, narrow mouth plates consist of 3–7 adambulacral plates which meet across the interradius; each bears a long, straight, slender, somewhat flattened spine. The madreporite is large, irregularly round, raised, and wartlike, covered with many fine gyri.

This species ranges from Maine to the Gulf of Mexico, in shallow water. It is the southern form of Asterias vulgaris, which ranges from Labrador to the Carolinas (and, rarely, to Florida). It is sometimes difficult for even a specialist to distinguish these two species, and hybridization is not uncommon, particularly in the Cape Cod area. This is one of the many cases among marine invertebrates which compels us to realize how very unsatisfactory are any of the proposed definitions of “species.”

MATERIAL EXAMINED.–Oregon Stations: 5894 (1) [R=83 mm, r=21 mm, Rr=1:4]; 6300 (12) [R=45 mm, r=11 mm, Rr=1:4]; 5882 (1) [R=22 mm, r=6 mm, Rr=1:4], Silver Bay Stations: 1564 (1) [R=20 mm, r=5 mm, Rr=1:4]; 1710 (1, with four arms) [R=42 mm, r=10 mm, Rr=1:4]; 1952 (4, two with four arms) [R=80 mm, r=18, Rr=1:4].

Coscinasterias Verrill

Cosinasterias Verrill, 1867:248. [Type, by original designation, C. muricata Verrill.]

Stolasterias (subgenus) Sladen, 1889:583. [Type, by subsequent designation, Asterias tenuispina Lamarck, 1816 (Fisher, 1923:128).]

Lytaster Perrier, 1894:09. [Type, by original designation, L. inaequalis Perrier (=Asterias tenuispina Lamarck, 1816).]

Polyasterias Perrier, 1894:108. [Type, by original designation, Asterias tenuispina Lamarck, 1816.]

Disc small; variable number (5–12) of moderately long, angular rays; single series of spiniferous actinal plates; adambulacral plates monacanthid throughout; only outer of two inferomarginal spines carries cluster of crossed pedicellariae; fissiparous.

Only one species is known from the western Atlantic.

Asterias forbesi, commonly known as Forbes sea star, is a species of starfish in the family Asteriidae. It is found in shallow waters in the northwest Atlantic Ocean and the Caribbean Sea.

Gulf of Maine to Texas

infralittoral and circalittoral of the Gulf and estuary