A group of giant manta rays swimming in the Indian Ocean. Photo: ImageSelect
Enormous giant manta rays with a wingspan of four to seven metres dive far deeper than previously thought. This may enable them to cross entire oceans.
The giant manta ray (Mobula birostris) can dive far deeper than marine biologists ever thought possible. Research on tagged giant manta rays off the coasts of northern Peru, eastern Indonesia, and northern New Zealand shows that they dive to depths of up to 1,250 metres. These dives may serve to escape predators and could explain why the species is found worldwide in (sub)tropical waters, an international research team reports in Frontiers in Marine Science of 15 October.
Tags
Giant manta rays, with a spectacular wingspan of up to seven metres and a weight of up to three thousand kilograms, are observed worldwide primarily in coastal waters of the (sub)tropics. To study their diving behaviour, twenty-four giant manta rays have been fitted with tags since 2012 that record data including depth; some can be read via satellite when they detach after several months, whilst others are recovered in their entirety when they wash ashore and are found.
In total, 2,705 days of swimming data from the manta rays were recorded in this way. On 79 days, manta rays dived to extreme depths, reaching a maximum of 1,250 metres. The majority of the deep dives (71) took place in New Zealand waters, where the seabed drops away relatively steeply.