These Feisty Hermit Crabs Brawl Over Snail Shells | 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.

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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.

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---+ 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

---+ Shoutout!

🏆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!

Lucas
Octo Valley
Sarmad Nasim
Harry To
Akash Chaturvedi

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[terramater]

Home is where your shell is! 🐚
Did you know that sometimes when a new shell turns up, hermit crabs will form a line, biggest to smallest, to see which animal fits the new shell? Crabs in general amaze us in so many different ways. Lately, we filmed Sally Lightfoot crabs while walking on water to escape from eels and octopuses. It was stunning!

[zoereidinger]

I love how many things live on the shell with the hermit crabs. You caught a whole bunch of species in your footage including barnacles, many kinds of algae, sponges, and hydroids.
Great work, as always!

[crakolington]

Hermit crab finds a dead snail corpse..
Hermit Crab: "It's Free Real Estate."

[Chezmeralda]

Hermit crabs are so cute I love how they scuttle around 😊

[kandyrew]

excellent this is exactly what i needed to watch this morning ❤️

[tannercarlson]

I would sit through these videos even if they were an hour long.

[MsWinterlife]

They are called “boarding crabs” or “tenant crabs” in Chinese, so I always knew they lived in someone else’s shells. Common name of animals can sometimes be quite efficient in explaining their lifestyle or behaviour, if the people giving those names have been observing very carefully.

[salsadipbox]

I remember thinking hermit crabs grow with their own shells and learning they grab snail shells to protect their soft yummy body blew my tiny 12 year old mind. This is sending me back to that moment, thank you! <3

[brianpj]

So cute and funny!! I love when they whip their little butts into the new shell 😂

[tgnm]

I always wonder how Hermit Crabs got their shells. Its actually from the snails!

[SpencerKlouds]

The way Laura narrates it and the background music makes me so interested to listen❤️❤️❤️

[dmedwards]

The way they swoop out quickly so nobody sees their little lower body 😂😍

[etsyziii]

Another worth the wait mini documentary. Keep it up, Deep Look! 😌❤

[avahampton]

i love the little shuffling sounds they make when switching shells

[teumehamada]

Man this Type of video is so relaxing, I love the narrator's voice.

[takayanagi-senseissurprise]

Basically when people hear about a sale in the mall but in the sea 🦀 🛍 🛒 🌊

[WorldScott]

Brings back memories of catching these guys up in Jenner. Great to see Deep Look cover them! Got another topic for your consideration: Click beetles! They are fairly common in the Bay Area and they'd make an excellent creature to cover. Cheers!

[TheAaa]

The crabs waiting for the snail to die before occupying its shell 👏 that even humans could learn. Big respect for these you too Deep Look 🙂

[danielzvids]

As always an amazing quality video! I loved watching it and learned something new 😍 Especially the footage of the crab with the open shell was really educational to see how they always keep hold of their shells. Thank you Deep Look ✌️

[jakubsolar]

Parents: Youtube is not a good entertaiment
After seeing this: Maybe I treated you too harshly