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This paper describes a new asterinid starfish found first in southern Britain, but now also known from the Mediterranean and the Adriatic. Detailed comparison is made between the new species and the closely related Asterina gibbosa in terms of morphology, reproductive biology and life-history. The new species is adapted for life on the upper parts of rocks and on perennial algae in intertidal rock pools; it is small in size, matures early, lays large eggs, broods its young and has a short life span.

Very few field studies of the population dynamics of starfish have been undertaken; such work depends upon being able to age individuals and identify age classes in the field. Information regarding growth rates in asteroids is notoriously difficult to obtain, due primarily to the absence of any method of assessing age, except where clear and obvious recruitment and regular growth provide size/age relationships. Numerous investigations of skeletal structures in asteroids by Smith (1940), Feder (1956), Hatanaka & Kosaka (1959) and Crump (1971) have failed to reveal any trace of growth lines similar to those found by Moore (1935), Jensen (1969) and Ebert (1970) in echinoids. In forcipulate asteroids, it is well established that growth depends primarily on temperature (Vevers, 1949; Hancock, 1958) and the availability of suitable food supplies (Mead, 1900; Galtsoff & Loosanoff, 1939; Smith, 1940; Vevers, 1949; Feder, 1956, 1970; Hancock, 1958). The food availability factor acts in such a way that it is impossible to tell the age of an adult starfish from its size; for example, in the spinulosan asteroid Patiriella regularts (Verrill), Crump (1969) found that specimens kept without food for 44 weeks lost 33 % of the original body weight, whilst P. regularts which had been fed on freshly killed crabs, showed a mean net increase of 629% of the original net weight over the same period.

A nursery roost of the soprano pipstrelle bat Pipistrellus pygmaeus has been monitored continuously between 1 April and 27 September (Weeks 1−26) for 20 yr to promote conservation of the species, which declined over the last century. The long-term study, essential to estimate a reliable population trend, is linked to environmental changes as possible causes of decline. The main emergence was from May to July (Weeks 6−18) when 550 ± 190 (SD) P. pygmaeus were counted. Analysis showed that the year-to-year change in population size of female P. pygmaeus (ΔN) and the time of the peak exit count of the females from the roost in May to June could be predicted from the integrated air temperature (degree days, D) between 1 January and 31 March.