Wikipedia calls this a "vacancy chain"

> In a vacancy chain, a new resource unit that arrives into a population is taken by the first individual in line, who then leaves his/her old unit behind, this old unit is taken by a second individual, leaving his/her old unit behind, and so forth

Neat!

https://en.wikipedia.org/wiki/Vacancy_chain

Hermit crabs are wondrous and hilarious. I had a couple as pets decades ago. That's before I knew about that industry and how it deprives these creatures of a beautiful, wild existence. The following is worth considering.

http://www.peta.org/living/companion-animals/7-reasons-never...

Crabsort: O(n)? It's a small set. Although there is a 4 plate/ five customer contention problem to boot. I can't tell if Crabsort is stable though.

Fortunately, everyone leaves with some spaghetti even if it's not a 100% optimal solution.

It should be 5 plates / 4 consumers, were it not for the late-arriving crab throwing a wrench in at the last minute.

Why was there only one shell left for the crab at the end?

There was an extra shell at the very beginning, so at the end it should be able to choose between 2 shells.

The Brits really are obsessed with queuing.

Hermit crabs are great scavengers and mostly peaceful, but they hardly wait for a shell to be vacant before moving in. They will definitely kill a live snail to take their shell if they need a bigger home. Or another crab.

I have a reef tank on my desk at work I get to watch this process happen on a daily basis. I have to keep adding larger shells to the tank because if I don't they will kill the snails and steal their shells. If there are enough shells available they leave the snails alone. Recently one of the medium size crabs decided to take the a shell that used to belong to a turbo snail, much too big for him as he can barely drag it around. I've come to the conclusion this crab is American and is going to fake it until he makes it.

you need a camera there. my old crabs where boring...

Maybe a stupid question... But if each hermit crab grows their first shell and the sheds it for something larger. Where do the larger shells come from? also why can't they grow subsequent shells after shedding?

The hermit crabs don't grow the shells. They use snail shells.

http://en.wikipedia.org/wiki/Gastropod_shell

Hermit crabs don't grow their first shell. They find all the shells they live in, often from sea snails apparently.

One of many reasons why everyone wants to be a crab.

https://en.wikipedia.org/wiki/Carcinisation

Well, this is not so simple as wikipedia says. Crustaceans are a really big and wide group of life forms, and Carcinisation can be applied only to some groups of decapods (about 15.000 extant species). There are also about 11.500 species of Copepoda, 10.000 Isopoda, 13.000 Ostracoda, 9.500 Amphipoda and 1.300 Thecostraca, for instance, and none of these are crabs.

I've seen this happening on the beach in Costa Rica. We'd been told about it and then to happen upon it actually occurring was quite a neat experience.

But where are the shells coming from?

Shellsort :D

Crab's have resolved homelessness , but were still screwing are species over with sub-prime loans.