Individual Variation in the Covering Behaviour of the Shallow Water Sea Urchin Paracentrotus lividus

Abstract

Abstract. A number of recent field‐based studies have investigated the possible functions of covering behaviour in a range of echinoid species. Some of these have found important relationships between covering behaviour and environmental factors, such as light (in particular, ultra‐violet light) and covering item availability. However, these studies have often shown considerable within‐species variation, thus making covering functionality both within and between species difficult to interpret. The present study experimentally investigates individual variability in covering behaviour characteristics of the sea urchin Paracentrotus lividus (Lamarck). Data were collected bimonthly over a 1‐year period at Lough Hyne, Ireland, by observing P. lividus in outdoor aquaria. Significant variations in covering behaviour characteristics were observed as a function of individual size and mobility but not as a function of sex. A significant relationship between water temperature, mobility and covering behaviour was also found and is hypothesized to have implications for grazing activity in P. lividus. In contrast to previous field studies of P. lividus at Lough Hyne, no summer ‘peak’ in the proportion of individuals covering was observed. However, there was a significant relationship between local solar radiation and ‘time to first cover’. Overall, these data highlight (i) the ecological significance of individual variation in P. lividus covering behaviour and (ii) the importance of investigating multiple factors as potential determinants of echinoid covering behaviour.

Spatial distribution patterns and population structure of the sea urchin <i>Paracentrotus lividus</i> (Echinodermata: Echinoidea), in the coastal fishery of western Sardinia: a geostatistical analysis

“…Its spatial distribution can vary on both small and large scales in relation to the interaction of abiotic and biotic factors (Boudouresque and Verlaque 2001). For example, the variability of water temperature and solar radiation can partially explain intraspecific variation in covering behaviour type in P. lividus (Crook 2003). The heterogeneity of the substratum plays a key role in providing P. lividus with shelter, thus influencing the structuring of populations, where predation pressure (which includes human harvesting) is particularly high (Bonaviri et al 2005.…”

Sea Urchin Covering Behavior: A Comparative Review

“…Glyptocidaris urchins, for example, were found to most likely heap for mechanical defense, and their place in the phylogeny suggests that this may be the ancestral reason for sea urchin crypsis (Figure 3). However, the effects of light intensity or the presence of predators have not been studied Strongylocentrotus urchins [7,19].…”

“…The reason for crypsis and the extent to which it is seen differs widely between species [14]. However, the behavior is also affected by size and mobility [19] as well as the energetic cost of covering [20]. It is possible, then, that the differences in the covering reaction between species are due to variations in animal size and mobility as well as energetic costs, rather than genetics.…”

Correlation analyses of covering and righting behaviors to fitness related traits of the sea urchin Glyptocidaris crenularis in different environmental conditions

“…Covering behavior, which is exhibited in species from both shallow (Verling et al, 2002) and deep (Pawson and Pawson, 2013) environments, refers to sea urchins using their tube feet and spines to move objects, such as shells, stones and algae fragments, onto their dorsal surface. A number of hypotheses have been tested to explain the evolutionary drives of covering behavior (Crook, 2003), including protection against exposure to solar radiation (Adams, 2001;Kehas et al, 2005;Dumont et al, 2007;Sigg et al, 2007), predation (Amsler et al, 1999;Agatsuma, 2001), desiccation (Orton, 1929), wave surge (Millott, 1976) and fl oating sand (Richner and Milinski, 2000), or/and as a refl exive action (Dambach and Hensel, 1970;Lawrence, 1976). Although it is considered that covering behavior is a behavioral avoidance strategy against UV radiation (Lamare et al, 2011), the fi tness benefi ts of this behavior remains largely unknown.…”

“…Correlation analysis is an important approach to investigating the fi tness basis of animal behaviors. Among the six hypotheses of potential functions of this behavior (Crook, 2003), protection against suspended sand is of particular interest. Richner and Milinski (2000) reported that covering behavior was signifi cantly enhanced in the sea urchin Paracentrotus lividus during exposure to suspended sand.…”