Guess what’s being released early this week as another nut crushing issue of Impurest’s Guide to Animals arrives on Comicvine. Last week the perplexing Paradox Frog and its giant tadpole hopped into the spotlight. This week’s creature is a tree climbing, coconut smashing behemoth. Hope you enjoy
Issue #25 - Robber Crab
Kingdom – Animalia
Phylum – Arthropoda
Class – Malacostraca
Order – Decapoda
Family – Coenobitadae
Genus – Birgus
Species – latro
Related Species - The Robber Crab’s closest relatives are the Terrestrial Hermit Crabs (1)
The Coconut Crusher
The Robber or Coconut Crab is the largest terrestrial invertebrate, reaching a leg span of just under a meter and a weight of four kilos. Adult Robber Crabs are truly terrestrial, possessing only vestigial gills and an organ called a Branchiostegel Lung to extract oxygen from the atmosphere. In fact Robber Crabs will drown if submerged in water for too long. The only connection to the ocean comes when the crabs breed, mostly due to the larval stage that spends four months drifting in the zoo-planktyon.
Robber Crabs forage using a sense of smell that has evolved to be similar to the type used by insects (2). While predominantly herbivorous Robber Crabs will scavenge on any vaguely organic material. Despite earlier assumptions very few Robber Crabs eat coconuts, despite climbing trees to remove the nuts. It’s been discovered that the crabs were mostly removing the husk to line its burrow, used when the crab has to moult its tough exoskeleton. Only the largest Robber Crabs can smash open coconuts to eat the flesh hidden inside the nut, although group efforts between multiple smaller crabs have been recorded
Robber Crabs have no natural predators save for Man (Homo sapiens sapiens), who in parts of its range, view the crab as food. It’s likely that before its extinction, on larger islands the Robber Crab had other natural predators. Besides subsistence hunting, some cultures believe that Robber Crab flesh is an aphrodisiac, although there is no scientific evidence to support this. In addition a large number of Robber Crabs are killed on roads criss-crossing their island homes
Five Fun Robber Crab Facts
Colouration of a Robber Crab varies from island to island. The exact reason why is still unknown.
Before you tuck into a Robber Crab stake beware that the species bio-accumulates toxins from the plants it eats within its own body tissues (3)
That said sometimes the crabs eat people. The amazing aviatrix Amelia Earhart was believed to have been scavenged on by Robber Crabs, after skeletal remains of a woman dating back to the 1930s were found in crab burrows (4)
Juvenile Robber Crabs are not so thick skinned. Instead they lug around an abandoned gastropod shell on their back until they get bigger.
Robber Crabs are real wanderers, they can be found kilometres inland, often in dense tropical forest
2 - Marcus C. Stensmyr, Susanne Erland, Eric Hallberg, Rita Wallén, Peter Greenaway & Bill S. Hansson (2005). "Insect-like olfactory adaptations in the terrestrial giant robber crab"(PDF). Current Biology
3 - S. S. Deshpande (2002). "Seafood toxins and poisoning".Handbook of Food Toxicology. Food Science and Technology119. New York, New York: Marcel Dekker. pp. 687–754.
4 - http://news.discovery.com/history/us-history/amelia-earhart-resting-place.htm
1 - http://upload.wikimedia.org/wikipedia/commons/c/c1/Birgus_latro.jpg
3 - http://www.sv-doodlebug.com/Pics2006/robber_crab2.jpg
4 - http://www.notcot.com/images/2011/10/crabs6.jpg
Thanks for reading guys; I hope you enjoyed the rowdy Robber Crab. Make sure to drop me a comment and suggest an animal to be covered in future issues, and as usual you can check out past issues in Impurest’s Bestiary.