From Deep Look.
Hermit crabs are *obsessed* with snail shells. These crafty little crabs, found in California’s rocky intertidal zone, are more than happy to let the snails build them a perfect home. When the crabs find a snail shell they like, they hop right into their new abode.
DEEP LOOK is an ultra-HD (4K) short video series created by KQED San Francisco and presented by PBS Digital Studios. See the unseen at the very edge of our visible world. Explore big scientific mysteries by going incredibly small.
Hermit crabs are one of the most recognizable and adored inhabitants of tide pools. But they aren’t just cute (for a crab).
“They’re one of the most important creatures in the intertidal zone because of their role as scavengers,” said Stephen Dunbar, a professor of biology at Loma Linda University. “They begin the process of cleaning up dead materials, like dead seaweed, fish, crabs, snails or whatever else.”
While hermit crabs scavenge for food, they also keep an eye out for new shells to call home.
Grainyhand hermit crabs seem to prefer turban snail shells. That’s good because turban snails are incredibly abundant in the intertidal zone. The snails can spend 20 years growing and building their shells as they graze on the algae that grows all over the rocks.
— What do hermit crabs eat?
Hermit crabs are scavengers. They eat decaying plants and algae in addition to dead animals.
— How do hermit crabs mate?
When it’s time for hermit crabs to mate they leave their shells briefly, mate, and then return to their shells. They are vulnerable outside of their shells so they do so quickly.
— Why do hermit crabs need shells?
Hermit crabs have stiff armored shells to protect their head, claws and walking legs. The back half of the hermit crab’s body, including it’s long curved abdomen, is soft to better fit inside a snail’s spiral-shaped shell. Without a snail shell to protect it, a hermit crab is vulnerable to predators.
—+ Find additional resources and a transcript on KQED Science:
—+ More great Deep Look episodes:
For Pacific Mole Crabs It’s Dig or Die | Deep Look
Decorator Crabs Make High Fashion at Low Tide | Deep Look
Whack! Jab! Crack! It’s a Blackback Land Crab Smackdown | Deep Look
🏆Congratulations🏆 to the following 5 fans on our Deep Look Community Tab for identifying the specially modified limbs hermit crabs use to grip their shells – urupods!
—+ Thank you to our Top Patreon Supporters ($10+ per month)!
Chris B Emrick
Allison & Maka Masuda
Joshua Murallon Robertson
Elizabeth Ann Ditz
Roberta K Wright
Shelley Pearson Cranshaw
—+ Follow KQED Science and Deep Look:
—+ About KQED
KQED, an NPR and PBS affiliate in San Francisco, California, serves Northern California and beyond with a public-supported alternative to commercial TV, radio and web media.
Funding for Deep Look is provided in part by PBS Digital Studios. Deep Look is a project of KQED Science, the largest science and environment reporting unit in California. KQED Science is supported by The National Science Foundation, the Dirk and Charlene Kabcenell Foundation, the Vadasz Family Foundation, the Gordon and Betty Moore Foundation, Campaign 21 and the members of KQED.