Influence of the commensal gastropod Crepidula plana on shell choice by the marine hermit crab Pagurus longicarpus, with an assessment of the degree of stress caused by different eviction techniques

Examining the impact of a symbiotic lifestyle on the fecundity of the marine gastropod Crepidula plana

“…The only other study we know of that has previously quantified egg capsule production and brood size for free-living and symbiotic By contrast, we saw no significant difference in the median number of embryos per brood (p = .844, Figure 5a) as a function of female substrate. Conklin (1897) also reported a maximum brood size of 9,000 embryos per free-living female (Table 2), consistent with reports by Hoagland (1986) (Pechenik et al, 2015), corresponding to a periwinkle shell length of ~26.3 mm (Li & Pechenik, 2004). However, at some study sites, individuals of C. plana have been found living inside hermit crab-occupied shells of much larger gastropod species (e.g., moon snails and the whelk Busycon carica) (Coe, 1948;Conklin, 1897Conklin, , 1898Gould, 1917Gould, , 1952Shenk & Karlson, 1986), which should allow the symbionts to grow to sizes substantially larger than those of the symbionts examined in the present study; indeed, adults of C. plana living in the shells of larger gastropod species can be up to 13 times larger than those found living in periwinkle shells (Conklin, 1897).…”

“…To encourage hermit crabs to vacate periwinkle shells housing individuals of C. plana, the hermit crabs were offered a variety of empty shells to move into; given a choice, hermit crabs of this species prefer shells that do not contain large individuals of C. plana (Pechenik, Diederich, Burns, Pancheri, & Dorfmann, 2015). The following day, hermit crabs that had not abandoned their original shells (occupied by individuals of C. plana) were evicted from those shells (Pechenik et al, 2015;Scully, 1979), and were then provided with empty periwinkle shells of appropriate size. All hermit crabs were later returned to their initial site of collection.…”

The effects of changes in temperature and salinity on the quality of shells selected by the hermit crab Pagurus longicarpus

“…The periwinkle shells used in the current study were collected from Nahant, MA. Each shell was inspected to ensure it was free of damage (except for drill holes, where intended) and symbionts such as Crepidula convexa (Li & Pechenik, 2004), C. plana (Pechenik, Diederich, Burns, Pancheri, & Dorfmann, 2015), Hydractinia spp. (Bach et al, 2006) or barnacles (McDermott, 2001).…”

“…Hermit crabs carefully examine shells to determine size, because shells that are too small can reduce their growth rate and leave them more vulnerable to predation and desiccation; thus, hermit crabs often occupy shells that leave some room for them to grow (e.g., Angel, 2000;Briffa & Elwood, 2007;Brodie, 2005;Spight, 1985;Vance, 1972). Hermit crabs also examine shells to determine shape (Arce & Alcaraz, 2012), the presence of damage that might leave them vulnerable to predators (McClintock, 1985;Pechenik et al, 2001;Pechenik & Lewis, 2000), and the presence of symbionts attached to the shell that might take up space or add unnecessary weight (Conover, 1976;Li & Pechenik, 2004;Pechenik, Diederich, Burns, Pancheri, & Dorfmann, 2015). Shells can deteriorate over time or by the action of predators of hermit crabs or predators of the original gastropods that made the shells (Pechenik & Lewis, 2000).…”

Methods of detection, collection and preservation of parasitic isopods (Isopoda: Epicaridea)

“…For paguroids inhabiting gastropod shells, the hosts must also be extracted from their shells prior to examination. Various methods, such as inserting a small wire or piece of fishing line through a drilled hole in the shell and lightly prodding the crab's abdomen (e.g., Brooks 1988, Damiani 2003, Pechenik et al 2015, are known to induce live hermit crabs into moving out of their shells; however, processing large, previously preserved samples requires a faster method. A mortar and pestle constructed of galvanized steel (Fig.…”