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Hermit Crab


Most species have long, spirally curved abdomens, which are soft, unlike the hard, calcified abdomens seen in related crustaceans. The vulnerable abdomen is protected from predators by a salvaged empty seashell carried by the hermit crab, into which its whole body can retract. Most frequently, hermit crabs use the shells of sea snails (although the shells of bivalves and scaphopods and even hollow pieces of wood and stone are used by some species). The tip of the hermit crab's abdomen is adapted to clasp strongly onto the columella of the snail shell. Most hermit crabs are nocturnal.


At Cove Bay, near the sea shore, at the foot of the Volcano, Mount Scenery, on Saba in the Caribbean Sea. Off course released after photoshoot.


As the hermit crab grows in size, it must find a larger shell and abandon the previous one. Several hermit crab species, both terrestrial and marine, have been observed forming a vacancy chain to exchange shells. When an individual crab finds a new empty shell it will leave its own shell and inspect the vacant shell for size. If the shell is found to be too large, the crab goes back to its own shell and then waits by the vacant shell for up to 8 hours. As new crabs arrive they also inspect the shell and, if it is too big, wait with the others, forming a group of up to 20 individuals, holding onto each other in a line from the largest to the smallest crab. As soon as a crab arrives that is the right size for the vacant shell and claims it, leaving its old shell vacant, then all the crabs in the queue swiftly exchange shells in sequence, each one moving up to the next size. Hermit crabs often "gang up" on one of their species with what they perceive to be a better shell, and pry its shell away from it before competing for it until one takes it over. There are cases when sea shells are not available and hermit crabs will use alternatives such as tin cans or any other types of debris or even custom-made shells.

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Super spotting Muckpuk,congrats on the well deserved SOTW and thanks for sharing.

Neil Ross
Neil Ross a day ago

A wonderful spotting, Muckpuk. Congrats on your SOTW.

Muckpuk 2 days ago

Thank you Sergio Monteiro, Brian38 and Ornithoptera80 for the congratulations!

Muckpuk 2 days ago

Thank you very much MichaelS and all other Rangers!
I am very honored!

Ornithoptera80 3 days ago


Brian38 3 days ago

Congrats, Muckpuk on SOTW!

Congratulations for the SOTW, Muckpuk.

MichaelS 3 days ago

Hi Muckpuk,

Congratulations! Your hermit crab spotting has been voted Spotting of the Week! The Project Noah community looks forward to seeing your next nature discovery!

Muckpuk a week ago

Thank you VERY much AntónioGinjaGinja!
Very honored to be considered!

Your spotting has been nominated for the Spotting of the Week. The winner will be chosen by the Project Noah Rangers based on a combination of factors including: uniqueness of the shot, status of the organism (for example, rare or endangered), quality of the information provided in the habitat and description sections. There is a subjective element, of course; the spotting with the highest number of Ranger votes is chosen. Congratulations on being nominated!

Muckpuk 3 months ago

Hi Neil Ross and Ava T-B

Isn't it just amazing that as soon as you think you can't get surprised anymore, plop, pops up another amazing thing in nature.....a row of waiting hermitcrabs... hope to see that one day!

Ava T-B
Ava T-B 3 months ago

Fascinating notes!!

Neil Ross
Neil Ross 3 months ago

I love these guys. Cool spotting, Muckpuk. Wonderful notes, as always :)

Spotted by

Zions Hill, Saba, Caribbean Netherlands

Spotted on Jul 10, 2020
Submitted on Aug 10, 2020

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