A comprehensive review of the literature on shallow-water asteroids (Echinodermata) recorded in Azores was carried out to establish a definitive list for the Archipelago. A total of 49 echinoderm species was compiled, comprising members of all extant classes; Crinoidea (1), Asteroidea (12), Ophiuroidea (11), Echinoidea (10) and Holothuroidea (7). References of asteroids occurence in the Azores, including historical records and distribution of asteroids from the Azores are given. Seven asteroid species recorded found in the Azores are found also in the Mediterranean and adjoining Atlantic coastlines, three are recorded from the Mediterranean and both sides of the Atlantic, one is limited to the Eastern Atlantic and one is circumtropical. Differences between the littoral hydrological conditions found on the North American coast and those in Azores makes the colonization from American coasts particularly difficult and probably are related to chance events like the episodic anomalies found in the general pattern of oceanic circulation. Asteroids are important in determining habitat structure for other species and can represent a substantial portion of the ecosystem biomass.

In September 2007, observations were made of a siphonophore in surface waters and near to the seabed by sea users off south Devon and south-east Cornwall. The same siphonophore was also recorded from regular samples collected offshore of Plymouth. The species is identified as Apolemia uvaria, which had not previously been recorded off Plymouth. It was sampled until March 2008 and re-appeared, in smaller numbers, in autumn 2008 until February 2009 but was not reliably reported in autumn 2009 (to end of October). The occurrence is unlikely to be due to sea warming, but more likely some variation in oceanic currents, possibly influxes of Atlantic water.