Hermit crabs aren't fussy creatures. Faced with a housing crunch, in many parts of the world, they have taken up abode in plastic and junk left by humans. But this is not without peril
It's tough being a hermit crab these days. Typically, these soft-bellied crustaceans protect themselves by living inside empty snail shells. But hermit crabs, today, face a housing crunch of epic proportions. People overharvest shellfish for food or pick up large numbers of shells on the beach to make door curtains or sundry other home embellishments, leaving very few seashells for hermit crabs.
In many parts of the world, these crabs have adapted. Ironically, they have been helped out of the housing shortage by trash left behind by humans. For instance, at Taiwan's Kenting National Park (knp), hermit crabs have taken to suitably persistent rubbish such as plastic containers, bottlenecks and bottle tops and light bulbs.
Usually, shells discarded by snails fit the bill, splendidly. What's more the crab's second home does not hamper its mobility: it just snuggles in on the creature's hind legs and protects its soft body, especially the abdomen -- that holds the delicate digestive glands and reproductive system.
Once a hermit crab adopts a shell, it carries its home, rucksack like, on its back -- until it outgrows the shell. This is no easy feat, considering a properly fitting shell has to be larger than the hermit crab that wears it.
Once a hermit crab senses danger, it withdraws into its shell, the hook like tail coils around the creature's home to seal it from inside, while the fourth and fifth pair of the crab's legs shrink to enable it to hold on to the insides of the shell.
There is another danger for the beleaguered crabs. Terrestrial hermit crabs have to return to the seas during the breeding season. This is a dangerous journey in fragmented habitats of protected areas such as the knp: the crabs have to cross highways, and are often squashed to death by speeding vehicles.
Plastic and glass products have left their imprint on the evolutionary history of hermit crabs. It's uncertain if these creatures will ever return to their original splendour.
With inputs from Kirtiman Awasthi
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