This study provides the first record of the beaded sea cucumber Euapta lappa at Madeira Island. A single individual was observed during a nocturnal scuba dive at 17 m depth, presumably feeding. After having its previous northern limit in the North-east Atlantic at the Selvagens Islands, this record expands the known distribution and northern limit of this tropical species by about 300 km. This new record of yet another tropical species expanding its range northwards can be seen as another indication of the ongoing tropicalization in the marine environment of Macaronesia in the North-east Atlantic.

Many of the most diverse clades of Late Palaeozoic echinoids (sea urchins) originated in the Devonian period. Our understanding of diversity dynamics of these Late Palaeozoic clades are thus informed by new systematic descriptions of some of their earliest members. The Proterocidaridae are a diverse and morphologically distinct clade of stem group echinoids with flattened tests and enlarged adoral pore pairs, which are first known from the Upper Devonian. We herein report on a new species of Hyattechinus, Hyattechinus anglicus n. sp., from the Upper Devonian of the North Devon Basin, Devon, UK. This is the first Devonian Hyattechinus known from outside of the Appalachian Basin, USA, and provides novel information regarding the palaeogeographic and stratigraphic distribution of proterocidarids in Late Devonian times. We additionally update the stratigraphic distribution of Devonian Hyattechinus from the Appalachian Basin, following recent biostratigraphic resolution of their occurrences. Hyattechinus appears to have been present in the Rheic echinoderm fauna during Late Devonian times, and comparison of the palaeoenvironmental setting of Hyattechinus anglicus with that of other Hyattechinus from the Famennian of the Appalachian Basin suggests that the genus may have preferred siliciclastic settings. Furthermore, this new taxon increases the diversity of echinoids from the Upper Devonian of Devon to three species.

The population size structure from a total of 876 individuals, together with published values of growth rate, maximum size and size at age were used to estimate an instantaneous rate of natural mortality (M) of 0.46–0.59 year−1 in a population of the sea star Archaster angulatus from south-western Australia. Peak abundance (17%) of all animals sampled was 105–109 mm arm radius (means of 4.2–4.8 years of age) and only one per cent of sea stars are predicted to live beyond 8 years in the population studied. There are few comparable studies on sea stars but when compared with rates of natural mortality in other echinoderms (sea urchins), A. angulatus is intermediate among species which exhibit the extremes of life history strategies, that is, those which grow very rapidly and may live just two years or less and those with very slow growth rates and which may live for decades.

Echinoderms are exclusively marine, osmoconformer invertebrates. Their distribution patterns are strongly influenced by salinity. Nevertheless, several species of the phylum inhabit the challenging intertidal zone, characterized by steep and fast salinity fluctuations. This study evaluated the response of coelomic fluid ionic concentrations (sodium, chloride, magnesium and potassium) of the intertidal sea cucumber Holothuria grisea to hypo- and hypersaline challenges. A stepwise protocol was performed for the whole animal exposure to both anisosmotic conditions: from 35 to 15 psu along 8 h, and from 35 to 45 psu along 6 h, to simulate intertidal conditions. Tissue water regulation by the longitudinal muscle, oesophagus and posterior intestine was also evaluated, upon hypo- and hyper-osmotic shocks of 20 and 50% of intensity with respect to the isosmotic control. Ionic gradients were observed between coelomic fluid and external water, mainly for potassium and magnesium, but also sodium, and in a greater extent under hyposaline conditions than under hypersaline exposure. Consistently, H. grisea shows retracted tube feet in 15 psu, but a more relaxed appearance and exposed tube feet in 45 psu. In addition, H. grisea showed greater capacity for tissue water maintenance during hyper- than in hyposmotic conditions. Holothuria grisea shows an avoidance behaviour in low salinity (thus sustaining ionic gradients), preventing its tissues from intense swelling. This strategy allows it to dwell in the intertidal region.

The sea cucumber stocks off the east and northwest coasts of Sri Lanka were estimated bysurveying 1307 km2 and 1779 km2 by an underwater visual census (UVC)in June and October 2008 respectively. The presence of twenty-five sea cucumber speciesbelonging to seven genera; Actinopyga, Bohadschia, Holothuria, Pearsonothuria,Stichopus, Thelenota and Acaudina was identified in fivehundred sampling sites randomly selected in each area. The overall average density (± SD) of sea cucumbers was higher in the northwest (350 ± 648 ind ha-1) than inthe east (90 ± 130 ind ha-1) and low-value species were predominant in bothsurvey areas (79 ± 125 ind ha-1 in the east, 244 ± 488 in the northwest) whencompared with medium (10 ± 34 ind ha-1, 105 ± 175 ind ha-1,respectively) and high-value category (<2 ind ha-1).The estimated total biomass in the northwest (13 024 t) was roughly four times greaterthan the east (3027 t). Holothuria edulis was the most abundant speciesin numbers while Holothuria atra had the highest stock biomass in bothareas. Sea cucumber densities were significantly different among the habitat(p < 0.001) and depth categories. The highestdensity was reported in rocky habitat associated with seagrass and / or macroalgae. Thedensity of low-value species was significantly high in 1–10 m depth category(p < 0.001) in the northwest while othercommercial groups were dominant in 20–30 m depth range in both areas. Temporal banning ofthe fishery for high and medium-value species would be a better management option to avoidfurther stock depletion.

New distribution information is given for three asteroid and one holothuroid species found in the eastern Pacific.

The impact of the “Erika” oil spill on the tidal rock pool community, and particularly on two species of sea urchin (Paracentrotus lividus and Psammechinus miliaris), was investigated over a 3-year period, at Piriac-sur-Mer (Department of Loire-Atlantique, France, 47°21.6' N; 2°31.7' W). A dramatic increase in the abundance of two macroalgae Ulva sp. and Grateloupia doryphora occurred following a 100% mortality of sea urchins observed three weeks after the oil spill. The density of sea urchins and of other main herbivores, the periwinkle Littorina littorea and the trochid mollusks Gibbula umbilicalis and Gibbula pennantii, were monitored between January 2000 and March 2003. There was significant inverse relationship between the overall density of herbivores (sea urchins, periwinkles and trochid mollusks) and the percent cover of algae in the tidal pools. The first urchins in the tidal pools were observed two years after the oil spill and it took three years to reach sea urchin densities comparable to the reference value of 63 ind.m−2 obtained before the oil spill.