Preferential feeding by the crab Necora puber on differing sizes of the intertidal limpet Patella vulgata

Abstract

The crab Necora puber L. is a common predator of limpets, the major grazer on rocky shores in Northern Europe. Information on interactions between crabs and their limpet prey is limited, extending mainly to limpet defensive and predator offensive tactics, while the importance of prey size on the outcome of such interactions remains largely unknown. Here, a laboratory approach was used to test for preference in feeding habits. Predation by N. puber with cheliped height 3 to 27 mm (carapace width [CW]: 16 to 77 mm) was examined on Patella vulgata with shell length 5 to 60 mm. Predator size (10,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and 21-25 mm cheliped height) and prey size (5-10, 15-20, 25-30 and 35-40 mm shell length) were examined, with 2 replicate tests for each predator-prey size combination. Crabs >10 mm in cheliped height (35 mm CW) predominantly crushed the shell of limpets <10 mm, while in the remaining combinations of predator and prey sizes, crabs prised limpets from the substratum. Size of limpet shell (vulnerability to crushing force) and resistance to leverage force were both important factors influencing the outcomes of crab-limpet interactions. For the largest crab tested (27 mm cheliped height; 77 mm CW), there was a size refuge for limpets > 41 mm in shell length. Field observations showed that the majority (94%) of limpets present in the intertidal zone are of a size that is vulnerable to predation by N. puber. For all sizes of crab examined, there were clear preferences for limpets smaller than the maximum size that the crabs were actually able to consume. Intriguingly, however, the preference experiment showed that, when given a choice, crabs consistently consumed proportionately more limpets of a larger size-class than when presented only with a single size-class at a time. Although further in situ studies are necessary, the present study indicates that size-selective predation by N. puber and other crabs may have an important influence on limpet population structure. KEY WORDS: Handling behaviour · Intertidal · Size refuge · Size preferenceResale or republication not permitted without written consent of the publisher

Rocky shores as tractable test systems for experimental ecology

“…Most of the suspension feeders are sessile, and many of the grazers and predators are reasonably slow-moving and sedentary enabling removal and exclusion experiments. Work over the last 20 years, however, has emphasized the importance of mobile predators such as foraging by crabs (Silva et al, 2008(Silva et al, , 2010(Silva et al, , 2014Christofoletti et al, 2011) and fish (Taylor & Schiel, 2010) when the tide is in, and birds when the tide is out (Hockey & Underhill, 1984;Coleman et al, 1999;Coleman & Hockey, 2008) or by diving (e.g. eider ducks, Hamilton et al, 1999).…”

Barnacle cover modifies foraging behaviour of the intertidal limpetPatella vulgata

“…The presence of any predators was also recorded during these visual observations. Previous observations showed that the main tide-in predators were the crabs Necora puber (Linnaeus, 1767), Carcinus maenas (Linnaeus, 1758) and Cancer pagurus (Linnaeus, 1758) (Thompson et al ., 2000; confirmed by more recent work by Silva et al ., 2008, 2010 a , 2010 b ). Predation by floating gulls on emersed limpets at the waterline occurred very occasionally (RCT personal observation).…”

Factors affecting the prevalence of the trematode parasite Echinostephilla patellae (Lebour, 1911) in the limpet Patella vulgata (L.)

“…It is a protandrous hermaphrodite, becoming sexually mature around 9 months transitioning from male to female at around 2-3 years (Orton et al 1956;LeQuesne and Hawkins, 2006). P. vulgata is preyed upon by a range of predators including crabs, fish (Silva et al 2004(Silva et al , 2008(Silva et al , 2010 and birds, including oystercatchers, Haematopus ostralegus del Hoyo and Collar, 2014 (Feare, 1971;Coleman et al 1999Coleman et al , 2004. Although juveniles are known to recruit into rock pools (Bowman and Lewis, 1977), as adults they are typically more abundant on emergent rock (i.e.…”