Pass the Pufferball

Photograph by Henley Spiers

Photographer Henley Spiers was in the water with members of a sea lion rescue group near the island of Espíritu Santo, Mexico, when something caught his eye. Two healthy young California sea lions (Zalophus californianus) were batting around a fully inflated guineafowl pufferfish (Arothron meleagris) like a ball. They seemed “delighted by the interaction” and showed no interest in eating the fish, Spiers later wrote. The behavior is apparently common enough to earn a name—“pufferball.” Photographers have also documented it among California sea lions elsewhere in Mexico, as well as among Galápagos sea lions in Ecuador and monk seals in Hawai‘i.

Pufferball might be a risky game. While pufferfish tend to be easy targets because they’re slow and, when harrassed, change into a tempting-to-bop ball by sucking water or air into their elastic stomachs, many are covered with spikes. Most dangerous of all, the majority of the 200 or so species of pufferfish contain a potentially lethal neurotoxin called tetrodotoxin, concentrated in their liver and ovaries. Only a handful of specialized creatures actually prey on pufferfish, including tiger sharks and sea snakes. But in Japan, pufferfish flesh, called fugu, is a delicacy—as long as it’s prepared to avoid the poisonous parts. Even when properly prepared, diners can sometimes experience tingles and lightheadedness. 

It may be that pufferball players experience similar sensations. After BBC Earth filmed juvenile male bottlenose dolphins playing catch with an inflated pufferfish—handling it gently, never biting down, and acting “blissed out”—some observers speculated that the animals were intentionally getting high on tiny doses of the toxin. Others believe sea lions may do the same. 

Whether or not that’s true, pufferball is one among many playful pinniped behaviors.

Australian and New Zealand sea lions throw kelp into the air and try to catch it. Antarctic fur seals kill penguins and toss them around like footballs but rarely eat them. Walruses splash seabirds, hit them with their tusks, or catch them in their mouths—usually without killing them. Meanwhile, sea lions bodysurf and practice underwater acrobatics. And when they combine those behaviors to play group games like pufferball, as Spiers witnessed, California sea lions may build skills for cooperative hunting.

Other play may similarly help pinnipeds prepare for dynamic social lives on land and for evading predators and pursuing prey at sea. Play-fighting, for instance, could prime them for the sparring that comes at mating time. Manipulating parts of their own bodies might help them distinguish between themselves and their environment. And manipulating inanimate objects and other living creatures likely prepares playful mammals for hunting.

Maybe all these behaviors are also just plain fun; research conducted with captive sea lions suggests that play and games measurably improve the animals’ well-being.