The brilliant blue waters of O'ahu's West Side serve as both shelter and playground for nai'a, Hawai'i's beloved spinner dolphins.
Following a long night of collaborating to catch lantern fish, shrimp, squid, and other deep-ocean prey, nai‘a (spinner dolphins, or Stenella longirostris) seek refuge at spots along Wai‘anae’s coastline like Mākua Bay and Pōka‘ī Bay. The sandy-bottomed bays offer more safety from predators and respite from big swells and wind.
After twice-daily journeys out to open sea to feed— once at sunset and again at midnight—nai‘a return to their beloved bays in sleep mode, brains half disengaged but still vigilant, young dolphins secure in the center of the pod. Upon awakening in the early morning hours, the dolphins celebrate their full bellies and safer surroundings with nose and tail slaps, “salmon leaps,” aerial spins, and somersaults.
"Of the 11 different species of dolphins and whales that are resident to Hawai‘i, spinner dolphins are the only ones that tend to display such strong fidelity to specific bays for resting,” says Robin Baird, a research biologist who has been observing local marine mammals for more than 20 years.
Though the motivation behind the spinning behavior of the nai‘a remains a mystery, Baird has a theory: Highquality images of the dolphins in aerial rotation almost always reveal parasitic remora fish (also referred to as “suckerfish”) on their bodies. While adults are usually effective at removing remora, juveniles struggle—and spin—more frequently.
With a population of 300 to 400, the collective of spinner dolphins that frequents O‘ahu and Maui is of a fission-fusion society. This means that spinners relaxing in one bay may head offshore together for foraging around sunset, mingle with groups from other shoreline resting spots, and then return home anew with a different set of companions.
Known for their aerial acrobatics, nai‘a have protective displays and curious social habits that offer humans a glimpse into a special world where cooperation and loyalty reign.