Putting "shoes" on your Toyota Land Cruiser is an unusual mod for a 4x4. Photographer Chris Bray did it (we showed it here) to prevent crushing crabs as he and his wife traverse Christmas Island, where some 40 to 50 million of the little red crustaceans conduct an annual mass migration.

Since not everyone is crafty enough to DIY such things, Christmas Island authorities have funded crab-centered infrastructure, like these overpasses:

Image credit: Kirsty Faulkner

Workers place crab-deterring barriers along the sides of certain roads, to steer crabs towards the overpasses and/or the underpasses they've created:

You might think maintaining infrastructure for crabs is easier than for humans--at a minimum, there's no graffiti to remove--but Parks Australia, which is responsible for the maintenance, writes that it still presents challenges:

"Five km of temporary fences has been added to the 12 km of permanent fencing that funnels the crabs along the sides of roads and into the underground crossings and a year's worth of leaves and debris has been raked out of the tunnels so the crabs can get through – it's a mammoth job that needs to be done quickly."