Interspecific competition for space by hydroids and a sea anemone living on gastropod shells inhabited by hermit crabs

Coexisting hermit crabs may competitively interact for shells and microhabitats, mainly when shell availability is habitat-related. Three species of Clibanarius (C. antillensis, C. sclopetarius, and C. vittatus) coexist in the intertidal region of Pernambuco Islet, Araçá Region, São Sebastião Channel, southeastern Brazil. This study evaluated crab preferences for four substrate types used by these species in nature (rocky shore, pebbles, sand, and mud) in allopatric (single species) and sympatric (three species) treatments in simulations of high tide and low tide. The substrate preference of the three hermit crabs did not vary between low and high tide situations. At low tide the crabs either moved into holes in the highly complex rocky substrate or buried themselves in mud. Substrate selection may explain the patterns of substrate use in nature only for C. vittatus. Clibanarius antillensis and C. sclopetarius showed closer similarities in the pattern of substrate selection in the sympatric treatment with the substrate use in nature than in allopatric treatment, indicating a positive influence (dependence) of the presence of one species on the presence of another. Use of sub-optimal substrates, mainly by C. antillensis, may be caused by other factors such as its low desiccation tolerances. If competition for space takes place among these species, it would be more intense between C. sclopetarius and C. vittatus given their higher overlap in substrate preference than between them and C. antillensis.

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Ecology of a parasitic barnacle, Koleolepas avis: relationship to the hosts, distribution, left–right asymmetry and reproduction

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315401004593 ◽

2001 ◽

Vol 81 (5) ◽

pp. 781-788 ◽

Cited By ~ 21

Author(s):

Yoichi Yusa ◽

Shigeyuki Yamato ◽

Masahiro Marumura

Keyword(s):

Positive Relationship ◽

Sea Anemone ◽

Hermit Crabs ◽

Sea Anemones ◽

Gastropod Shell ◽

Wet Weight ◽

Left Right Asymmetry ◽

The Right ◽

Dwarf Males

The pedunculate barnacle Koleolepas avis is a symbiont of the sea anemone Calliactis japonica, which lives on gastropod shells carried by large hermit crabs, usually Dardanus arrosor. Relationships with the host sea anemone, distribution on the gastropod shell, left–right asymmetry and reproduction of the barnacle were investigated. A larger number of barnacles occurred on shells with greater ‘cylindroid dimensions’ of sea anemones. Distribution of barnacles on shells was not random: assuming the in situ position of the shell carried by the hermit crab (∼45° inclination), there were more barnacles along the lower part of the anemone disk than the upper part. Large barnacles lie on either the left or right sides of their capitula, and those lying on the left side (Type L individuals) tended to occur along the left side of the host, and those on the right side (Type R) along the right side. Barnacles [ges ]0·016 g in wet weight had egg masses, and there was a positive relationship between body weight and number of eggs. Koleolepas avis has both hermaphrodites and dwarf (complementary) males attached to them. Large hermaphrodites tended to have larger dwarf males than smaller hermaphrodites.

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Response To Con- and Heterospecific Male Odours By the Voles Micro Tus a Grestis, M. Arvalis and Clethrionomys Glareolus With Respect To Competition for Space

Behaviour ◽

10.1163/156853980x00276 ◽

1980 ◽

Vol 73 (3-4) ◽

pp. 277-302 ◽

Cited By ~ 14

Author(s):

Gerrit De Jonge

Keyword(s):

Interspecific Competition ◽

Home Cage ◽

The Other ◽

Clethrionomys Glareolus ◽

Microtus Agrestis ◽

Heterospecific Male ◽

Competition For Space ◽

Per Se

AbstractAdults of Microtus agrestis, M. arvalis and Clethrionomys glareolus were offered the opportunity to explore an experimental alley, a section of which contained male odours of either of the three species. Neither of the species explored one of the sections of the alley more than the other one if the choice was between a section with conspecific odour and a non-odorous section. Both M. agrestis and C. glareolus preferred the non-odorous section when the choice was between M. arvalis odour and a non-odorous section. If an encounter with another vole was arranged in the alley before the opportunity was given to explore the partly odorous alley, then some additional avoiding responses to odours were assessed. M. agrestis now avoided both alien male conspecific odours and its own home cage odours. M. arvalis now avoided both the odours of C. glareolus and M. agrestis. Other responses to odours were not affected by an encounter. An encounter per se did not lead a vole to avoid the place where it had taken place. The survival value and the possible role of the avoiding tendencies in intra- and interspecific competition for space are discussed. Probably, odour avoidance is only an additional way in the communication between voles.

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