1. Vevers (1949) observed that with an abundant food supply, juvenile specimens of Asterias rubens could increase their radius at a monthly rate of slightly more than 10 mm in summer and autumn, and slightly less than 5 mm per month in winter.
2. Orton & Frazer (1930) recorded an increase in diameter of 2.5 mm per month on average, and 5.0 mm per month maximum in Asterias rubens.
3. Nichols & Barker (1984 b) followed the growth of annual cohorts in a population of Asterias rubens on an intertidal reef in Torbay, South Devon, UK, for three years. Growth was most rapid in the year following settlement and during the warmer months of the year. The average increase in starfish diameter over the first year was 28.5 mm, and over the second, 13.0 mm. The mean monthly increase in diameter over the three year period of the study was 2.2 mm. Starfish on the reef became sexually mature in their second year after attaining a diameter of 5 cm.

Feeding
Asterias rubens preys upon a wide range of living organisms and carrion that include molluscs, polychaete worms and other echinoderms. Occasionally, small crustaceans are caught on the suction discs of the tube feet. Asterias rubens preys upon bivalve molluscs by forcing the bivalve's shell open with its tube-feet, the tips of which attach to the bivalve shell by suction. Once a tiny gap (<0.1 mm) is established between the valves of the prey species shell, the starfish everts its stomach lobes into the bivalve and commences digestion.

Detailed experimental studies (Castilla & Crisp, 1970, 1973; Castilla,1972) have established that Asterias rubens has a well developed olfactory sense with adaptive preferences and avoidances. Asterias rubens demonstrates positive rheotaxis (purposeful movement of a motile organism in to a water current), which is enhanced in the presence of living prey such as Mytilus edulis (Castilla, 1972 ) and reversed in the presence of a predator Crossaster papposus (Castilla, 1972b).

Other species of the benthic fauna, including prey species Marthasterias glacialis, Buccinum undatumand several species of ophiuroids, demonstrate avoidance reactions in the presence of the predatory starfish Asterias rubens (Feder & Arvidssen 1967; Russell, 1984). These species can detect Asterias rubens owing to the release of a surface-active saponin from its body surface (Mackie et al. 1968).