Scientists Need Your Help Peeping on the Lugworm’s Weird Mating Habits

UK scientists are recruiting volunteers to look for the critters’ “sperm pools”

Lugworm "casts" on a beach. Cdling/Wikimedia Commons

The lugworm, a slimy red-tinged critter that is often used as fishing bait, can be found on beaches across the British Isles and northwest Europe. The worms cluster in large groups—with populations as dense as 100 to 150 per square meter—but for such a ubiquitous species, lugworms’ mating habits are a little … unusual. They would rather stay buried in the sand than venture out into the world to find a partner (the lugworm is all of us), so the males cast their sperm onto the beach and the tide carries it to the burrows of the females.

Scientists don’t know much about the environmental conditions that foster this weird mating ritual, so as the BBC reports, researchers at the University of Newcastle have asked “citizen scientists” to help them learn more about how the lugworm— Arenicola marina, if you will—gets it on.

The initiative, part of a broader survey called “Capturing Our Coast,” asks UK residents who live near beaches to walk down the waterline at low tide. Participants are instructed to count lugworm sperm pools and casts—tube-like ribbons of sand that are created when the worms burrow into the beach, by keeping a stopwatch running as they walk across a 50 meter transect. More detailed instructions are available on the Capturing Our Coast website, along with answers to pertinent questions like “What’s the difference between bird poo and sperm puddles?”

Dubbed “Spermwatch” (there’s really no doubt about what participants are getting into here), the survey will help UK scientists learn more about the conditions that trigger lugworm breeding. Lugworms are an important part of the marine ecosystem: they are a primary food source for birds and fish, and help circulate nutrients in the sand. Their hemoglobin-rich blood may also be a viable blood substitute for humans. As the Spermwatch survey instructions note, however, “impacts of climate change on our marine environment could affect the lugworm's ability to breed, endangering the population.”

The project is now in its second year, Natasha Frost reports for Atlas Obscura, but the surveys have yet to yield any clear results. Jacqueline Pocklington, project coordinator of Capturing Out Coast, tells the BBC that lugworms were spotted “quite patchily from shore to shore in different regions” last year.

“We urgently need more surveys again this year to better understand what is affecting the worms' reproduction,” she adds.

A little effort from volunteers can go a long way in unlocking the mysteries of lugworm romance. “It is an easy survey,” Capturing Out Coast’s website says, “as you don’t need any training and all the family can take part,” Forget board game night, everybody. Spermwatch is where it’s at.

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