Previous studies had associated nematodes with manatee skin. One in 2011 described an “extraordinarily” long-tailed diplogastrid nematode, Cutidiplogaster manati, found in skin lesions on West Indian manatees in an aquarium in Okinawa, Japan. That piqued the interest of these authors, who hoped to learn more about C. manati. In 2013, they began collecting samples from Florida manatees in the Crystal River National Wildlife Refuge, and the project became Mr. Gonzalez’s master’s thesis.
The team found what was probably C. manati — and two other nematodes.
Mr. Gonzalez, working alongside researchers conducting an annual health assessment of manatees, collected dead skin from the tails of seven of the mammals in 2018 and another seven in 2019. The collection process is comparable to a human back scratch, and the animals are swiftly returned to the water, Mr. Gonzalez said, to minimize stress.
The samples were examined under a microscope, then their DNA was extracted. The new nematodes had large teeth — maybe for eating other nematodes, or for “something tricky,” such as splitting open diatom algae and consuming their insides, said Robin Giblin-Davis, a recently retired nematologist at the University of Florida and a co-author of the study. The team speculates that C. manati and one of the others, a previously unidentified species they called “Long Tail,” might use their lengthy tails to anchor themselves in the waves.
Though more work is needed for formal species descriptions of the two new nematodes, “I think you could comfortably say these are new species,” said Adler Dillman, an associate professor at the University of California, Riverside, who was not involved in the study.
The nematodes, the study suggests, are specially adapted to flourish in this decaying micro-landscape, where structures on the skin would be as tall to them as trees are to people. All three manatee nematodes were found on all of the manatees sampled in 2018 and 2019, but no skin lesions were found; the authors concluded that it was unlikely that the nematodes were hurting their hosts. Perhaps, they suggested, they’re passed between manatees like human skin mites.
For now, the researchers hope to generate more enthusiasm for nematodes as well as their gentle manatee hosts.