Featured Image Credit: Ryan Williams via National Geographic
By Kira Krall
National Geographic’s Crittercam program has documented the secret lives of over 70 species since its inception in 1986. And for the first time, they’ve successfully been deployed on manta rays in Mexico’s Pacific waters. The cameras worn by the animals themselves record video and audio as well as data like temperature, depth, acceleration, and GPS location. Joshua Stewart collaborated with Crittercam creators Greg Marshall and Kyler Abernathy on the project.
While the cams are a technological feat, the suction cup normally used for smooth marine mammal skin had a difficult time sticking to the manta rays. Rays, sharks, and their relatives (the cartilaginous fish) have hydrodynamic armor called “dermal denticles” that make their skin feel like sandpaper. This texture practically refused to hold on to the suction cup, and some of the cameras fell off the mantas in under a minute.
However, some cameras stayed on for nearly three hours. Using good, old fashioned scientific observation, the team determined that the more mucous the manta’s skin had, the better the suction. So how did they replicate the sticky substance in the field with no spare equipment? They used peanut butter.
Suction cups attached with this average pantry item stayed on for about six hours, doubling the recording time of the nut-free cameras. Stewart and his team collected a total of 180 hours of footage. Watch a video of the Stewart deploying the Crittercams below:
What we know of mantas comes from studying them where we can see them, usually in the brightly lit waters that humans frequent on SCUBA and snorkel trips. The Crittercam documented mantas foraging at much greater depths than we thought. They were found diving to the thermocline, or the area in the water column where surface water suddenly begins to cool.
The thermocline can be anywhere from 660-1,000 feet or beyond depending on factors like where you are on the planet and oceanic weather patterns. Revelations like this are not uncommon in the Crittercam world. Last year, the cams discovered the secrets of leopard seal foraging.
Knowledge like this is vital to the protection of the species. Mantas are frequent victims of bycatch and are a targeted fishery species. They are collected for their meat, skins, and highly valuable gills, which are sold in China for $309 dollars a pound. However, science like the manta Crittercam project has helped communities switch from fishing to ecotourism. This can end up benefiting local people, as global manta ecotourism brings in $180 million annually. Manta fisheries make a mere 3% of that figure.
Here’s to hoping that simple solutions like peanut butter can keep saving the world!
You can read more about the Crittercam and watch exclusive videos here.