Platypodiella spectabilis Credit: Ellen Muller
With all due respect to Neoliomera, perhaps the most coveted carcinological treasure to be found on coral reefs are the Clown Crabs of the genus Platypodiella. Like a red and yellow Rorschach test, these diminutive invertebrates epitomize the visual splendour we associate with marine life. No two specimens ever share the exact same pattern, always showing some amount of variation in their spots and colors, like so many crustaceous snowflakes. The vibrant patterning isn’t merely for ostentation either, as these crabs actually sequester palytoxin, one of the most lethal poisons known in nature.
A sponge-associated specimen, reportedly feeding on a commensal zoantharian. Credit: Ellen Muller
In total, five species are described, split along the geographic boundaries of the major ecoregions of the Atlantic and East Pacific. The crab most likely to find its way into aquarium exports is the Caribbean P. spectabilis, known in field guides as the Gaudy Clown Crab. It can be found from Florida south to Brazil, the latter of which may represent an undescribed cryptic species. On the other side of the Atlantic, P. picta is recorded from tropical reefs along the West African coastline, while the recently described P. georgei hales from St. Helena. A pair of species are found in the East Pacific: P. rotundata along the Mexican coastline and the possibly conspecific P. gemmata from Panama to the Galapagos Islands, neither of which are well-documented in photographs. These crabs have a fascinating ecological relationship with zoantharians, seemingly relying on them for both shelter and nourishment. Juveniles are reported to somehow settle into the internal cavity of their preferred host (Palythoa spp.), eventually burrowing beneath the colony as they mature into an adult 30mm in carapace width. This burrow and its small opening to the outside world is where this industrious fellow will call home for the remainder of its days.
Picking apart its Palythoa host. Credit: Garcia-Hernandez et al 2014
There are, however, other places they are known to reside. One of the more interesting is their reported association with certain sponges (a ropelike grey sponge and the vaselike Niphates digitalis) which harbor an entirely different type of zoantharian, the commensal Umimayanthus parasiticus. Since these polyps don’t form any appreciable mat, the crabs instead burrow directly into the sponge, creating a small alcove from which they emerge at night to feed.… More:
The post The Kaleidoscopic Platypodiella Clown Crabs appeared first on Reefs.com.