On 31 January 2008 a recreational diver vacationing on the island of Kuramathi (4º58′08′′N 74º17′20′′E), Maldives, photographed an unknown species of hermit crab (Crustacea: Anomura: Diogenidae) inside an unusual shelter (Figure 1). This consisted of half of a plastic box, widely distributed throughout the world, inside chocolate eggs and containing a small toy. The crab's shelter was about 2.5 cm long and 3.0 cm in diameter.

Fig. 1.

Unidentified species of hermit crab inside a plastic box at Kuramahti Island, Maldives Archipelago, Indian Ocean, January 2008. Photograph: Jorge Ávila.

Hermit crabs have a wide variety of shelters detailed by several authors (e.g. Turra & Denadai, Reference Turra and Denadai2002; Nakin & Somers, Reference Nakin and Somers2007) and these play highly important roles in their overall ecology (e.g. Biagi et al., Reference Biagi, Meireles, Scelzo and Mantelatto2006).

Unusual shelters are also referred to by authors (Garcia et al., Reference Garcia, Meireles and Mantelatto2003) while plastic shelters are even proposed as alternative shelters for hermit crabs with, apparently, important ecological results albeit for terrestrial species (Elizabeth Demaray, unpublished data).

Increased pollution and shell collection together with greater influx of tourism especially in tropical areas such as the case here described, may well have a negative effect on hermit crabs' long term survival and population stability. Aspects such as non-stable, light, predator attracting, brightly coloured and poor hydrodynamic shelters are important study subjects that do deserve our attention. The question of plastic debris in the oceans is, of course, a matter of much wider relevance already emphasized more than 20 years ago (Wilber, Reference Wilber1987).