Unusual shelters occupied by Brazilian hermit crabs (Crustacea: Decapoda: Diogenidae)

NOTE AND COMMENTS

Unusual shelters occupied by Brazilian hermit crabs (Crustacea: Decapoda: Diogenidae)

Garcia, R. B.; Meireles, A. L.; Mantelatto, F. L.

Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (USP), Av. Bandeirantes 3900, CEP 14040-901, Ribeirão Preto, São Paulo, Brazil

^{Correspondence}

Hermit crabs are commonly found occupying gastropod shells. However, some hermits are known to utilize a variety of alternative shelters such as tusk shells, serpulid tubes, cavities of stones, sponges, dead corals, pieces of bamboo, bivalve shells (see Imafuku & Ando, 1999), and/or a variety of gastropod shells with the exterior surface colonized by organisms that affect shell selection (see Brooks & Mariscal, 1985). Despite the 47 hermit crab species recorded in Brazilian waters (Melo, 1999; Mantelatto et al., 2001; Nucci & Melo, 2003), there have been no reports on type of shelters other than gastropod shells occupied by hermit crabs on the Brazilian coast.

In December 2000, a male of Dardanus venosus (H. Milne Edwards, 1848), and a female of Paguristes erythrops Holthuis, 1959 (3.2 and 3.9 mm in shield length, SL, respectively), were caught by SCUBA methods on the rocky surface of the infralittoral area (9 m depth) of Anchieta Island (23^o33'S, 45^o05'W), Ubatuba region, São Paulo State. The male D. venosus inhabited a bivalve shell (shell aperture width, SAW = 10.0 mm; shell aperture length, SAL = 9.4 mm) of Chama congregata Conrad, 1833 (Fig. 1A), and the female P. erythrops a gastropod shell (SAW = 3.8 mm and SAL = 6.7 mm) of Favartia cellulosa (Conrad, 1846) totally covered by live corals of Astrangia rathbuni (Vaughan, 1906) (Fig. 1B).

On February 2001, one male and one female (6.9 and 3.0 mm of SL, respectively) of Dardanus insignis (Saussure, 1858) were collected on soft bottom substrate (35 to 45 m depth) with a double-rig trawl net in Caraguatatuba Bay (23^o 57'S, 45^o 28'W), and São Sebastião Island region (23^o44'S, 45^o02'W), northern coast of São Paulo State. The male inhabited a barnacle shell (SAW = 14.4 mm and SAL = 12.3 mm) of Balanus venustus (Darwin, 1854) covered by small cirriped shells of the same species (Fig. 1C); and the female inhabited a gastropod shell (SAW = 5.0 mm and SAL = 10.0 mm) of Fusinus brasiliensis (Grabau, 1904) covered by a colony of unknown bryozoan (Fig. 1D). Voucher specimens collected are deposited in the Crustacean Collection of the Biology Department of FFCLRP, University of São Paulo, Brazil (DB/FFCLRP/USP 1087 to 1090).

As far as we known, the present communication is the first report of uncommon shelters used by hermit crabs in shallow waters of the Brazilian coast. It is important to note that the majority of specimens in all species reported here were found occupying gastropod shells in the natural populations (99.8% of the total) studied in the same region (Mantelatto et al., 2001; Mantelatto & Garcia, 2002).

No deformities in pleopod, abdomen or pereopod morphology were observed in these hermit crabs. However, the length of the exopod of the uropods were measured, and the asymmetry index (AI) was calculated following Van Valen (1962); AI = (L – R)/(L + R), with L and R being left and right measurements, respectively. The index varies from +1 (left longer) to –1 (right longer), with 0 indicating perfect symmetry. The female D. insignis had almost symmetrical uropods (0.15), while the others presented markedly left-biased asymmetrical uropods (0.24 for D. venosus; 0.21 for male of D. insignis; and 0.24 for P. erythrops). The present study reports isolated cases of uncommon hermit crab shelters in the São Paulo coast.

Acknowledgments — The authors are grateful to FAPESP (Grants 98/07454-5; 99/11679-5; 00/02554-3; 98/07090-3) for financial support in sampling work. Special thanks are due to Drs. Osmar Domaneschi (IB – USP), Fabio Pitombo (UFRRJ), Alvaro Migotto (CEBIMar – USP), and Adilson Fransozo (UNESP) for assistance with shell, cirriped, and coral species identification, and for making available hermits collected during BIOTA/FAPESP program, respectively.

REFERENCES

BROOKS, W. R. & MARISCAL, R. N., 1985, Shell entry and shell selection of hydroid-colonized shells by three species of hermit crabs from the northern Gulf of Mexico. Biol. Bull., 168: 1-17.

IMAFUKU, M. & ANDO, T., 1999, Behaviour and morphology of pagurid hermit crabs (Decapoda, Anomura) that live in tusk shells (Mollusca, Scaphopoda). Crustaceana, 72: 129-144.

MANTELATTO, F. L. M. & GARCIA, R. B., 2002, Hermit crab fauna from the infralittoral zone of Anchieta Island (Ubatuba, Brazil). In: E. E. Briones & F. Alvarez. Modern approaches to the studies of crustacea. Kluwer Academic/Plenum Publishers, New York, pp. 137-143.

MANTELATTO, F. L. M., GARCIA, R. B., MARTINELLI, J. M. & HEBLING, N. J., 2001, On a record of Dardanus venosus (H. Milne Edwards) (Crustacea, Anomura) from the São Paulo State, Brazil. Revta. Bras. Zool., 18: 71-73.

MELO, G. A. S., 1999, Manual de identificação dos Crustacea Decapoda do litoral brasileiro: Anomura, Thalassinidea, Palinuridea e Astacidea. Plêiade Editora, São Paulo, 551p.

NUCCI, P. R. & MELO, G. A. S., 2003, A new species of Pagurus (Decapoda: Anomura: Paguridae) from Brazil. J. Mar. Biol. Ass. U. K., 83: 351-353.

VAN VALEN, L., 1962, A study of fluctuating asymmetry. Evolution, 16: 125-142.

Received May 10, 2002

Accepted July 11, 2002

Distributed November 30, 2003

(With 1 figure)

Publication Dates

• Publication in this collection
  15 Mar 2004
• Date of issue
  Nov 2003