What are the sympatric mechanisms for three species of terrestrial hermit crab (Coenobita rugosus, C. brevimanus, and C. cavipes) in coastal forests?

Abstract

Terrestrial hermit crabs play a significant role in coastal ecology. For example, as seed dispersers and debris scavengers in coastal forests, they accelerate the decomposition of organic substances. In the Indo-Pacific Ocean, Coenobita rugosus, C. brevimanus, and C. cavipes are the three most common species of terrestrial hermit crab. Because the mechanisms that contribute to the sympatry of these three species of crab have not been identified, this study investigated the three most likely explanations: niche differences, competition, and predation. The results showed that the three species displayed niche differences in terms of seasonal activity, habitat, utilization of shells, and food preference, suggesting that competition for resources is avoided. The habitat of terrestrial hermit crabs in Taiwan is closely associated with that of humans. Our study helps improve our understanding of the ecology of terrestrial hermit crabs and their conservation.

Seaward migration and larval release of the land hermit crab <i>Coenobita</i> <i>brevimanus</i> Dana, 1852 (Anomura: Coenobitidae) on Iriomote Island, Japan

“…Seaward migration of C. brevimanus showed clear seasonality, and many crabs migrated and entered into seawater in July to September when seawater temperature and monthly precipitation were higher ( 25°C and 200 or 100 mm), but only a few crabs were found on the beach in months with lower temperature and precipitation (May, June and November). This pattern was similar to the seasonal changes in the number of crabs observed by field survey on Ishigaki Island (Kosuge & Kohno, 2010) and Taiwan (Hsu et al, 2018). The peak period of seaward migration between July and September is the reproductive season for other coenobitid crabs on Yeayama Islands (Sato & Yoseda, 2008Doi et al, 2016Doi et al, , 2018a.…”

“…The land hermit crab Coenobita brevimanus Dana, 1852 (Anomura: Coenobitidae) is widely distributed and a common species throughout the Indo-Pacific area (Hartnoll, 1988;Vannini & Ferretti, 1997;McLaughlin et al, 2007;Hamasaki et al, 2015a;Hsu et al, 2018). The southern islands of the Japanese archipelago are the extreme northern limit of the biological range of this species.…”

Gastropod shell use by the land hermit crabs <i>Coenobita brevimanus</i> and <i>C. cavipes</i> in an abandoned village on Iriomotejima Island, Japan

“…Coenobita cavipes in Sakiyama and other areas, on the other hand, occupied shells of land snails (Shimamura, 1987;Yamashiro, 1987;Kosuge & Kohno, 2010;Kohno et al, 2015). Unlike in Taiwan (Hsu et al, 2018), among all Coenobita species in the Ryukyu Islands, C. cavipes is considered to be the most terrestrial one; they use shells of terrestrial and freshwater gastropods (Hamasaki et al, 2017).…”

“…Yet, C. brevimanus and C. cavipes from Sakiyama (this study) and Itona (Kosuge & Kohno, 2010) seem to be unable to use T. (M.) argyrostomus shells (as observed by smaller body sizes). This is likely due to the fact that C. brevimanus prey on its congeners (Hsu et al, 2018), thus suggesting C. cavipes, as well as other Coenobita crabs, are competing for T. (M.) argyrostomus shells.…”

“…This region is known to have one of the highest densities of Coenobita crabs in the world (Tohyama & Kurozumi, 1987), where several species can coexist in some habitats. One coexistence mechanism of Coenobita crabs includes differences in behavioral seasonality (Doi et Crustacean Research 49 Hsu et al, 2018) and specific preference in shell occupancy (Abrams, 1978;Barnes, 1999Barnes, , 2003Hsu et al, 2018;Steibl & Laforsch, 2020).…”