Masking material as a form of food storage in Tiarinia cornigera and Micippa platipes (Brachyura, Majidae)

Abstract

Masking or decorating, which means attaching materials to the body, was investigated in two spider crabs Tiarinia cornigera and Micippa platipesin the subtropical waters of Okinawa, Japan. This life strategy was compared between sites over a period of time. All crabs of different ages and sizes attached materials, in one combination or the other, on their bodies proportionate to their carapace sizes. Older or larger crabs had their carapaces more completely covered with the materials than young or smaller crabs. Similar materials were found at all sites and had equal selective precedences by crabs. Red algae, particularly Gelidiella sp, was the most frequently selected material over the other groups of brown, green algae and sand. The brown algae Dictyota linearis was the most dominant species in the stomach contents. However, this species like a few others was not selected for masking. Availability and probably the nutritive values of the algal species are discussed as probable reasons for selection of these materials for masking. These materials were strategically selected, stored on carapaces and used as food sources.