Distribuição e padrões de utilização das conchas de caranguejos eremitas (Anomura) da Costa do Algarve

Almeida, Cheila

http://hdl.handle.net/10400.1/352

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Authors

Almeida, Cheila

Advisor(s)

Erzini, Karim

Gonçalves, Jorge

Abstract(s)

The hermit crabs population of Algarve Coast on soft bottom, until 30 meters depth, between Faro and Portim?o, was analysed within the scope of a project on the biologic characterisation of the sea bed. Samples were made with a beam trawl. Weight and morphometric data were taken from the specimens as well from their associated shells with the objective to characterise the shell use. Eleven species were identified, presenting a new record of Pagurus chevreuxi to Portuguese coast. Diogenes pugilator was the specie most abundant and most relevant in the community, being the most important in all seasons except in winter and dominant in the 0-10 meters range depth. This dominance can be related with the continuously reproduction during all year, it has a dominant attitude in regard with the others and an adaptation to some environmental conditions like hydordinamism. Two more species, Anapagurus laevis and Spiropagurus elegans, together with the last one were permanent in the community, being the first one the most important between the 20-30 metres depth, and the second in the winter. A total of 38 gastropods species, a sponge and a cnidaria covering all the shell were identified with hermit crabs. From these just 19 have been found in the habitat as living gastropods what can represent a preference of shells apart of the availability. The gastropod shell more used was Turritella communis, apart being the fourth species in the gastropod community of the sampled area. Diogenes pugilator was the most versatile specie using the highest number of gastropod species. The shell diameter was the best factor to explain the use of shells by the hermit crabs. These crabs seem to choose the shell that better adjust to their body because it makes easier the movement and protect them when confronting with other individuals or predators.