Many single-celled organisms collect genes from other organisms — a process known as horizontal gene transfer — but multicellular organisms tend not to. Tiny invertebrates called bdelloid rotifers were found to buck this trend, taking on genetic material from a range of other species, including bacteria, fungi and plants.
Multicellular creatures rarely do this because their germ line is sequestered in the gonads, explain Eugene Gladyshev, Matthew Meselson and Irina Arkhipova at Harvard University. Bdelloid rotifers are different. They often experience desiccation, potentially opening up their cell membranes to chunks of outsider DNA. This unusual way of injecting diversity into their genomes may help to explain why these rotifers have gone 40 million years without having sex.