FAR FROM BEING FREE-RANGING LONERS, MANTA RAYS BOND WITH EACH OTHER in relationships that often last for extended periods, according to a five-year study of manta ray socializing in Indonesia.
Some mantas form loosely connected groups to hang out with. Not surprisingly, like their human counterparts, female mantas form much tighter friendships with other females than males do among themselves. The males? Well, the boys’ groups were looser and they tend to cruise more.
MANTA RAY SOCIALIZING COMES IN TWO DIFFERENT STYLES
The findings resulted from a five-year study of reef mantas (Mobula alfredi) at Indonesia’s Raja Ampat Marine Park. As a richly diverse, relatively isolated site, the rays were more likely to act naturally. Over the course of their research they tracked individual mantas by their spots and markings in some 3,400 encounters, observing more than 500 groups of the gentle giants.
They found two trends in the manta population. Mature females tended to group together with fairly strong social bonds. Males, other females and juveniles tended to hang out in less tightly-knit groups.
The all-female groupings possibly reflect efforts to minimize harassment from males looking to mate, the authors suggest, while the males’ less-intense style may reflect interest in feeding and finding mating opportunities.
Whatever, there’s no suggestion that the mantas form lifelong relationships, as do some species of other fishes. The manta group friendships tend to last for periods of weeks to months, not years or decades.
For Manta Ray Facts: Manta Rays: Gentle Giants Explained
FAVORED SPOTS: CLEANING STATIONS
Cleaning stations appeared to be significant rendezvous points for the mantas, places where they could be cleaned of parasites and dead scales by wrasses and other cleaning fishes.
But while cleaning stations are a logical place to find lots of mantas, the researchers found that specific social groups – more often females – were consistently spotted at these locations, and that some had strong preferences for specific sites.
The study suggests that the mantas choose “to socialize with other individuals that they know , and that they remember their social contact with those individuals,” study lead author Rob Perryman told National Geographic. “They have friends, to put it in quite and anthropomorphic way.”
The paper, by scientists from the Marine Megafauna Foundation, Australia’s Macquarie University, the University of Papua and the U.K.’s University of York, was published in the journal Behavioral Ecology and Sociobiology.
NOT NECESSARILY NEWS TO DIVERS
The study deals with manta-to-manta socializing, but the gentle giants’ propensity for making friends perhaps isn’t news to divers who’ve found themselves encountering them in other situations.
In news coverage of a report last year about juvenile manta rays and Flower Garden Banks National Marine Sanctuary off the Texas coast, one sanctuary staff member noted that the gentle giant rays seemed to like just hanging out with them during dives. I found this to be the case during my own 20-minute dance with an adult female manta at Flower Garden Banks last summer.
IMPORTANT FOR PROTECTIONS
Pristine environments like Raja Ampat are of increasing interest to tourists, the study’s authors note, suggesting that understanding manta behavior is important for protecting them in habitats and furthering sustainable ecotourism and conservation initiatives.
Reef mantas, experiencing population declines in some regions and threatened by issues ranging from plastic pollution to habitat destruction, are listed by the International Union for the Conservation of Nature as vulnerable to extinction. They are sometimes hunted for their gill plates, used in traditional Chinese medicine.
PRINCIPAL SOURCES: Manta Rays Form Social Bonds with Each Other, Study Shows, Marine Megafauna Foundation Newsroom; Manta rays form close friendships, shattering misconceptions, National Geographic; Reef manta rays make friends — but some are more social than others, Australian Broadcasting Company; These manta rays form ‘friendships’ that last longer than a summer fling, Science Magazine Daily News Feed; Social preferences and network structure in a population of reef manta rays, Study Abstract, Behavioral Ecology and Sociobiology.