Champion Crab Races Day

What the day is

Champion Crab Races Day is observed on February 17. No origin is documented. Crab races are real, generally run with hermit crabs at seaside resorts, and the animals themselves are more interesting than the racing.

Origin and background

The sideways walk is a matter of joinery. A crab's legs hinge in a single plane that runs across the body rather than along it, so the efficient direction of travel is lateral. Moving forward would mean working the joints against their range. Some crabs with differently proportioned legs, including spider crabs, do walk forward, which confirms that the gait follows the anatomy rather than the other way around.

The hermit crab's housing problem produces the remarkable behavior. Hermit crabs do not grow shells; they occupy empty snail shells and must move to a larger one as they grow, and suitable shells are scarce. When a new shell arrives on a beach, crabs gather and arrange themselves beside it in a line ordered by size. Once a crab large enough to take the vacant shell appears, it moves in, and the next crab down takes the shell just vacated, and so on down the queue, so a single new shell can rehouse a dozen animals in a few seconds. Biologists call it a vacancy chain, the same term used for job or housing markets, and it is one of the few places the structure appears outside human economies.

The welfare note matters if the day tempts anyone. Hermit crabs sold as souvenirs are almost all wild-caught, they need humidity, deep substrate for molting and a supply of larger shells, and they can live for decades when properly kept.

How to take part

• Watch footage of a vacancy chain. It looks organized enough to seem staged.
• Race on hands and knees, which is the version the day intends.
• Leave empty shells on the beach. Collecting them removes housing stock.
• Watch a crab's legs and see why sideways is the efficient direction.
• Do not buy a hermit crab as a prize or an impulse.