Asterias forbesi

Asterias forbesi usually has 5 arms but occasionally has 4 or 6. Like many starfish species, the upper surface is covered in blunt conical projections giving it a rough feel. Some of these are pedicellariae, minute pincers that can grip objects. The arms are plump, broad at the base and tapering to a blunt tip. This starfish grows to about in diameter with an arm length of about . The madreporite is usually pink and is visible near the edge of the disc. There are several rows of tube feet on the underside on either side of the ambulacral groove that run down the centre of each arm. The colour of the upper side is variable, ranging from brown or tan to reddish-purple and the underside is usually pale brown. Near the tip on the underside of each arm there are small eyespots. These are not set on short stalks as they are in the otherwise similar Asterias rubens with which this species can be confused. ==Distribution==

Asterias forbesi is found in the intertidal zone of rocky shores on the Atlantic coast of North America from Maine southwards to the Gulf of Mexico. Asterias rubens has a more northerly range, being found from Labrador southward to Cape Hatteras, most commonly north of Cape Cod living in colder, deeper waters. ==Behaviour==

Asterias forbesi feeds on bivalve molluscs and other marine invertebrates. It can open shells by gripping the two halves with its tube feet and forcing them apart. It then inserts its stomach, turning it inside out in the process, and secretes enzymes, digesting the body of the mollusc in situ. The sexes are separate in Asterias forbesi. Sperm and eggs are liberated into the sea and fertilization is external. The starfish in any area may synchronise their emission of gametes which will increase the chance of fertilization taking place. The eggs hatch into bipinnaria larvae which form part of the zooplankton and develop over a period of about three weeks before settling on the seabed and undergoing metamorphosis into juvenile starfish. ==Ecology==

The ciliate parasite Orchitophrya stellarum has been found in the gonads of up to 20% of male Asterias forbesi in Long Island Sound. They feed on the tissue of the gonad and effectively castrate their host. A small number of females were also found to contain the parasite. ==References==