New Aquatic 'Roly-Poly' Found in Los Angeles

The new species Exosphaeroma pentcheffi. Kelsey Vo Bailey

During a field trip to a seaside park less than a mile from the Port of Los Angeles, a class of college students and their professor found a bizarre-looking new species of aquatic pill bug, also known colloquially as a roly-poly.

The students, from Loyola Marymount University, found the creature clutching the arm of a sea star. "As soon as we saw this bumpy little guy, we knew it was something special," said their professor, Natural History Museum of Los Angeles scientist Dean Pentcheff, in a statement.

They took the specimen back to the museum, where other scientists helped identify it using a scanning electron microscope. Due to its small stature, roughly the size of a BB (the 4.5-millimeter round pellets shot from BB guns), they couldn't use a regular microscope for taking pictures of it, Pentcheff says.

The species, named Exosphaeroma pentcheffi (after Pentcheff), is recognizable because of the raised, peg-like protrusion on its back, and its unique tail-like uropod, which it uses to swim.

"It is amazing to think that you can discover a new species in one of the most urban places in the world like the Port of Los Angeles," said museum scientist Adam Wall, the lead author of the study describing the species, published in the journal ZooKeys.

In the process of describing the new pill bug, the scientists looked through the museum's collections for something similar. They accidentally found that a separate specimen, collected in Alaska 142 years ago, had never been fully described and was in fact also, technically, a new species. They named it Exosphaeroma paydenae in honor of Joan Payden, a supporter of science at the museum.

Pill bugs are actually crustaceans, and the roly-polys that many are familiar with actually have gills. That is why they are always found in moist environments, such as in leaf litter, and why, if you put them in a terrarium without plenty of water, they will quickly suffocate.

A male and female of Exosphaeroma pentcheffi, the newfound Los Angeles marine pill bug species. Kelsey Vo Bailey