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One of the science blogs I check regularly is Darren Naish’s Tetrapod Zoology, currently hosted by Scientific American. Naish has a taste for the gratifyingly obscure, and the blog’s science-to-polemic ratio is high. He recently wrote about a remarkable case of mutualism—a reciprocally beneficial cooperative relationship between organisms of different species—that was described by a group of Japanese scientists in the journal Marine Biology. 

Two years ago the research vessel Oshoru Maru, conducting a hydrographic survey in the western North Pacific, encountered a school of 57 ocean sunfish. These truly odd fish are among the stars of the Monterey Bay Aquarium. They’ve been called “swimming heads”; to Milton Love, author of Probably More Than You Want to Know About the Fishes of the Pacific Coast, an ocean sunfish resembles “a Frisbee designed by Salvador Dali.” Also known as molas, sunfish feed mainly on jellyfish, salps, and other gelatinous creatures. They’re often seen at the surface, lying on their sides and waving their fins in what appears to be a random manner. Most of the fish seen from the Japanese ship had several 

parasitic copepods (marine crustaceans) attached to the bases of their dorsal fins. 

At some point a Laysan albatross—the same species as the celebrated Al, who has been visiting Point Arena every winter—joined the fish. “As time elapsed, the fish followed this particular bird,” wrote lead author Takuzo Abe and his colleagues. Eventually it approached a sunfish and picked off a copepod. This attracted another Laysan and three black-footed albatrosses. “Some ocean sunfish appeared to present themselves by swimming sideways next to birds. Sequential pictures showed a number of birds removing and ingesting at least four ecto-parasites.” 

One interesting thing about this observation is that it isn’t altogether new. In 1940, UCLA ornithologist Loye Miller speculated in a Condor article that black-footed albatrosses gleaned parasites from molas off the California coast: “A sunfish was actually seen to swim toward a pair of resting albatrosses and turn on its side. However, the birds were disturbed before I could see any actual delousing take place. It does seem likely that they might act as ‘tick birds’ for the great inert molas.” 

My friend John Westlake, a veteran whale-watching guide, says he has seen albatrosses associating with, even standing on ocean sunfish. Milton Love describes an interaction between a sunfish and a gull of uncertain species: “On two occasions, I have seen sunfish come to the surface, flop on their sides and wave their exposed pectoral fins about. On both of these occasions, a sea gull paddled over and pecked at the fish for a little while. When the bird finished, it moved away and the fish turned over and went through the same motions. The gull returned and pecked for a few moments more. Perhaps heavily parasitized fish come to the surface to elicit cleaning.” 

Such relationships have been described for a number of aquatic and terrestrial species: cleaner wrasses and cleaner shrimp that remove external parasites from a variety of reef fish; freshwater fish that perform the same service for hippos; the African tickbirds that Miller alluded to, although they may take a little blood from their ungulate associates along with the ticks. Western scrub-jays have reported to harvest ticks from black-tailed deer. It’s just one variant among the numerous ways that different organisms can interact, from casual commensalism to committed symbiosis. 

The Japanese scientists’ report would have made Petr Kropotkin, the anarchist prince and contemporary and critic of Darwin, very happy. In his book Mutual Aid, Kropotkin emphasized cooperation over competition as the key to evolution. It’s been pointed out that while Darwin and Wallace developed their evolutionary ideas after spending time in the crowded tropics, Kropotkin’s thinking bore the stamp of Siberia. With his field experience in a place where both human and animal life was sparse and widely dispersed, the Malthusian model didn’t make a lot of sense to him. What he saw was the cohesion of the reindeer herd and the tactical coordination of the wolfpack. 

Kropotkin overstated his case, of course, as the so-called Social Darwinists overstated theirs. It’s always risky to construct a theory of society from observations of animal behavior. At least he, unlike the Ron Paulite cowboy libertarians and the Black Bloc yahoos, had a theory of society. Smashing or shrinking the state only gets you so far. As Dylan didn’t say: to live outside the law you must have a high tolerance for committee meetings. 

The prince was clearly onto something important, though. (Kropotkin’s true intellectual heir is the late Lynn Margulis, who was convinced that evolution was driven by symbiotic mergers.) Cooperation, either within or across species boundaries, can enhance the fitness of the cooperating individuals. The molas that developed a way to lighten their parasite loads by getting a seabird’s attention presumably left more descendants than those that didn’t.