Devils of the Mediterranean
Off the coast of Corsica, a group of volunteers seeks to find out more about the elusive giant devil ray population living in the Mediterranean Sea.
It’s 6am and my alarm is ringing in my ears. I wipe my tired eyes, get dressed quickly and am ready for another day aboard one of two research vessels floating off the French island of Corsica. On deck, the team prepares for a long day of monitoring the ocean. I’m on the first shift, getting in position to spot any movements in the water around us. After hours of looking out at the deep blue, one of us sees a disturbance in the water. Our boat slowly and carefully approaches the estimated point under sail so as not to scare away the animals we are looking for. We count on the curiosity of this intelligent species to not disappear while we inch closer. I get my underwater camera ready to document the events, while others set up the scientific protocols before hopping into the water.
I slip calmly into the ocean at the back of the boat with the help of a lifeline and gaze down into the depths of the Mediterranean Sea. Only endless blue below me. In this moment, I think about the several dozen kilometres that separate me from the Corsican coastline, while I wonder how many thousands of metres of water lie under me. Suddenly, all other thoughts disperse as I spot what we are looking for on our mission: the giant mobula rays (Mobula mobular) of the Mediterranean. I see their graceful dance in the distance, their flat, diamond-shaped bodies and long fins moving in the sunlight, and wait for them to come closer. With luck, the rays will show interest in the divers and the boat so that the scientific procedures can be easily carried out. If the team is careful enough, the interaction might last several minutes and give the team vital information on the giant devil rays that inhabit the Mediterranean Sea.
The giant devil ray feeds on krill and small pelagic fish and has a dark back, a darker black scarf on its head and a white belly. The mouth is positioned on its ventral side and is framed by cephalic lobes, a criterion that for a long time served to distinguish mobula rays from manta rays, in addition to size and distribution. The filter feeder’s pectoral fins are long and triangular, with a wingspan able to reach 3,2m. On average, however, an individual’s wingspan measures between 1,8m and 2,80m. As the only species of the genus observed in the Mediterranean Sea, it was long believed that the species was endemic. However, researchers established that its range extends over all temperate and tropical waters. As a pelagic species, it can be found at the surface off the coast, as well in depths of up to 1,200m. Individuals of this species sometimes form impressive shoals; the largest aggregation to be observed in the French Mediterranean happened on July 3 in 2018 when 39 individuals were counted.
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