If you’re a mite looking to travel, you could do worse than being swallowed by a slug. These spherical arachnids (pictured), most shorter than a millimeter, can trek up to 4 meters in the belly of a gastropod—about 2000 times farther than they can get on their own, according to a new study.
To make the find, researchers collected slugs and snails from a forest in Germany and examined their feces for live and dead mites. Then, they determined how well mites can survive digestion by feeding a known number to slugs and counting how many emerged alive in the feces. Finally, they let slugs defecate on sterilized soil without mites and checked the soil for mite populations 3 weeks later.
Thirty-one out of 42 slugs, and seven out of 15 snails swallowed mites. Their combined feces contained at least 36 species of mites, and more than two-thirds of them were alive. Various other organisms also popped up alive in the mollusk feces, including springtails, ciliates, nematodes, mosses, and plant seeds.
This form of dispersal, called endozoochory, is also how fruit seeds are dispersed by the birds that eat them. The findings, published this month in Oecologia, suggest that snails and slugs could be transporting whole communities of soil invertebrates and plants. And that means entire communities of animals and plants could move together, perhaps even into new habitats.