Sex, size and colour in a semi-terrestrial crab, Heloecius cordiformis (H. Milne Edwards, 1837)

Tanya Detto*, Jochen Zeil, Robert D. Magrath, Sarah Hunt

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)

    Abstract

    We investigated the relationship between sex, size and colour in the little studied Australian endemic semaphore crab, Heloecius cordiformis, and related it to the crabs' social system with the aim of identifying the potential signalling function of claw colour. Equal sampling of crabs from all size classes revealed a strong relationship between sex, size and claw colour. Purple-clawed males were larger and had larger claws than pink-, orange- or green-clawed males. Male claws showed positive allometric growth: relative to body size, purple-clawed males had larger claws. The largest females had pink claws; the few with purple claws were no larger than immature green-clawed crabs. Female claws grow isometrically with the body so the relative claw size did not differ among the female colour classes. Quantitative measurements of claw colour revealed spectral differences between these subjectively described colours. The purple claws typical of large males also contrasted more strongly against the mudflat background than the other colours. Heloecius copulate outside female-owned burrows and probably within male-owned burrows. The male's waving display, in which both claws are raised and lowered, may feature in both mating strategies: as a territorial display and to attract wandering females. Large males are competitively superior so size, and potentially colour, are important in territorial disputes and may also feature in mate choice.

    Original languageEnglish
    Pages (from-to)1-15
    Number of pages15
    JournalJournal of Experimental Marine Biology and Ecology
    Volume302
    Issue number1
    DOIs
    Publication statusPublished - 29 Apr 2004

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