Dupond & Dupont

Dupond and Dupont came to me as rehomes from a family whose kid had moved on to other things, and many years later they’re still teaching me something new every season. They’re named after the Tintin detectives because they kept swapping shells, making it impossible to tell who was who. One has since outgrown the other, which finally blew their cover.

Their home is two 30 gallon aquariums stacked into a climbing tower, because hermit crabs are surprisingly athletic explorers, with 8 inches of sand for digging, both saltwater and freshwater pools, and humidity kept above 80%. That last part isn’t optional: hermit crabs breathe through modified gills and would slowly suffocate in dry air. They’re observe-only pets, though after all these years they no longer hide when I approach. Favorite treats include worm castings and the fresh clover sprouts I plant right in their enclosure.

Land hermit crabs (genus Coenobita) are not true crabs and are not actually hermits. In the wild, they live in large social colonies along tropical shorelines, and they can live several decades with good care, often outliving the family dog. Because their soft abdomen has no shell of its own, they borrow discarded sea snail shells and trade up as they grow. Dupond and Dupont are partial to turbo shells, which get genuinely hard to find in their size now that they’ve grown so much.

Fun fact: when a good empty shell washes ashore, hermit crabs will line up beside it from biggest to smallest and wait. When the biggest crab moves into the new shell, the next one takes its old home, and so on down the line, so one lucky find can rehouse the whole queue. It’s called a vacancy chain, and it’s one of the animal kingdom’s best examples of an orderly housing market.