How Hermit Crabs Find Their Shells

September 29, 2015
A hermit crab is crawling on a sandy beach near virgin islands ecotours

Ever wonder how a hermit crab finds its perfect shell? Some shells are too big and some are too small and pretty soon this becomes a retelling of Goldilocks. But several different species, both terrestrial and marine hermit crabs, have developed their own system of finding one that’s “just right.” How? They’ve been known to form vacancy chains as a way to exchange shells between them.


It works like this. One crab finds a vacant shell, but alas, it’s too big for him. Instead of moving on he waits there. Soon, other hermit crabs arrive, they see that the vacant shell is too big for them as well, but they wait, and they all begin to form an orderly line ranging from the biggest among them to the smallest. Finally, when the right size hermit crab comes along he sees that the vacant shell is just what he needs: the perfect upgrade, room-wise, for him to continue to grow. He abandons his old shell, and all the hermit crabs waiting in line rapidly exchange theirs in sequence, so by the end of it, they all have a larger shell that is just right for them.


Hermit crabs are fascinating creatures and on our Mangrove Lagoon Cas Cay tours you get a chance to see them face to face and even participate in a hermit crab race!

Please join our monthly newsletter!

You May Also Like


Three people are in a yellow ocean kayak

Cas Cay Kayak, Hike & Snorkeling Ecotour

A black map pin with a circle in the middle on a white background.

St. Thomas

A black and white hourglass icon on a white background.

3 Hours

Embark on an exclusive morning adventure through the serene beauty of Cas Cay, where tranquil mangroves, vibrant marine life, and breathtaking volcanic vistas await—discover this hidden gem with knowledgeable guides.

A group of people are walking down a path towards the ocean.
A black map pin with a circle in the middle on a white background.

St. John

A black and white hourglass icon on a white background.

3 Hours

Hike & Beach Adventure Tour: Discover Honeymoon Beach on St. John

Looking to pack a BIG experience into a short amount of time? Then we’ve got just the adventure for you! This tour is designed for groups of 4 or more.

A group of people are swimming with sea turtles in the ocean.

Swim alongside graceful Hawksbill and Green Sea Turtles in the crystal-clear waters of St. Croix on this unforgettable guided snorkel tour. Explore vibrant coral reefs and encounter diverse marine life with expert guides ensuring a safe and memorable experience. Perfect for all skill levels, this unique adventure offers an up-close look at St. Croix’s stunning underwater world—an experience you’ll never forget.

A black map pin with a circle in the middle on a white background.

St. Croix

A black and white hourglass icon on a white background.

1.5 Hours

St. Croix's Best Snorkeling with Sea Turtles

Other Blogs


sustainable ecotourism in the US Virgin Islands
By Chrissann Nickel April 23, 2025
Sustainable ecotourism is about curating a mindful way for our visitors to explore the Virgin Islands in ways that protect the environment, respect the local culture, and support the VI economy.
A person is sitting in a chair on a beach under a palm tree.
By Chrissann Nickel March 27, 2025
St. John is an incredibly picturesque island. Those white sand beaches, the sparkling aquamarine water, and those dramatic green hillsides… both locals and visitors alike can’t resist pulling out their phones to snap one more picture, again and again. And don’t get us started on those Virgin Islands sunsets! Whether you’re a first time visitor to the island, or will be coming back soon on your 36th annual vacation, every trip to STJ is special—and every trip is worth commemorating with fresh photos. One of our newest experiences that we’re excited to offer is our Private Photoshoot Tour . On it, you’ll be matched with a talented professional photographer who will take you to some of St. John’s most stunning photo ops and take photos of you that are 1,000x better in framing, lighting, and style than those your well-meaning taxi driver took for you off the side of the road (he tried his best, but… we said what we said ;) ). In celebration of this new tour, we thought we would share some of our personal favorite photography spots on St. John. Here they are, in no particular order:
A large body of water with boats in it and a city in the background
January 16, 2025
Discover what to do in St. John—from hiking scenic trails to snorkeling with sea turtles. Explore unforgettable, family-friendly adventures on this Caribbean paradise!
Two women are paddling yellow kayaks in the water.
January 1, 2025
Discover the best of St. Thomas with kayaking, snorkeling, and hiking adventures! Explore mangroves, vibrant reefs, and scenic trails with Virgin Islands Ecotours for unforgettable island memories.
A woman sits in a yellow ocean kayak
December 26, 2024
Explore the best outdoor adventures in the U.S. Virgin Islands! From kayaking mangrove lagoons to snorkeling with sea turtles, discover top activities on St. Thomas, St. John, and St. Croix.
A walkway leading to the ocean on a sunny day.
December 24, 2024
Join Virgin Islands Ecotours' award-winning tours on St. Thomas & St. John. Combine USVI tours to kayak, hike, & snorkel into an unforgettable experience. Book now!
A beach with the words merry christmas written in the sand
December 11, 2024
Join Virgin Islands Ecotours' award-winning tours on St. Thomas & St. John. Combine USVI tours to kayak, hike, & snorkel into an unforgettable experience. Book now!
St. Thomas Virgin Islands
November 20, 2024
Explore Virgin Islands St. Thomas with the ultimate guide to kayaking, snorkeling, hiking, and more. Discover top adventures and plan your trip today!
A boat is floating on top of a large body of water surrounded by small islands.
October 10, 2024
Join Virgin Islands Ecotours' award-winning tours on St. Thomas & St. John. Combine USVI tours to kayak, hike, & snorkel into an unforgettable experience. Book now!
Show More