Bone worms are called ‘zombie worms’ for a good reason: They don’t have mouths or guts. Yet, that doesn’t prevent them from eating whale carcasses and otherwise proliferating deep in the ocean and puzzling scientists.
The 6-inch creatures, which use acid to dissolve their meals and absorb the nutrients, were known to be mostly female bone worms, with males living only as larvae within their bodies. Now, researchers have just found a new male species that can grow to the same size as females and display very uncanny characteristics during mating.
The findings about the male bone worms were detailed in a study published in the December issue of Current Biology. Author Greg Rouse, a marine biologist at Scripps Institution of Oceanography at UC San Diego, wrote that worm’s entire body “has evolved as a tool for mating, and that’s why we named it Osedax priapus, the mythological god of fertility.”
Scientists collected bone worms at a depth of nearly 2,300 feet by an Monterey Bay Aquarium Research Institute remote-operated vehicle and were surprised to find that the male worms of the new species they observed were “tens of thousands of times larger than those of other Osedax worms,” Phys.org reported.
The male bone worm has evolved from living within females to being able to stretch ten times its usual length to reproduce, which is considered an “evolutionary reversal” with “retained genes that allowed them to grow to full size,” according to a UT San-Diego report.
“Evolutionary reversals to ancestral states are very rare in the animal kingdom,” the study’s co-author Robert Vrijenhoek wrote. “This case is exceptional because the genes for producing full-sized adult males should have deteriorated over time due to disuse. But apparently the genes are still there.”