Donald Trump cats (#TrumpYourCat) have doting owners to fashion their hair into yellow, Trumpy coiffures. Sponge crabs, of the family Dromiidae, manage without such luxury. The sponge crab is drawn toward its hairpiece by a deep, evolutionary need for protection. A young crab will approach a sponge and "feel around with its pincers and snip off a piece," says Mary Wicksten, a biologist at Texas A&M University. It then tailors the sponge to fit its shell and goes through a rather elaborate hairdressing ritual, hoisting the sponge onto its back with a pair of short, hooklike legs. Only then is the crab complete.

Once the crab is sponged, its fear of death is somewhat eased, as sponges smell bad to kani-loving octopuses and fish. It is then free to troll the ocean floor for seaweed, worms, and other morsels of protein. (When it comes to food, says Wicksten, "the crab is not fussy at all.")

For its part, the sponge feels no pain (sponges lack nervous systems). Actually, it benefits from the relationship. The sponge needs a good flow of water through its pores. As the crab scurries along, the sponge gets a ride through the water column, where its mesh body fills with nutrients.

This article appeared as "Trump Crab" in the November/December 2015 print edition of Sierra.