Giant manta ray
|Giant manta ray|
Giant Manta ( Mobula birostris )
|( Walbaum , 1792)|
The giant manta ray ( Mobula birostris , Syn .: Manta birostris ) is a species of ray from the family of devil rays . “Manta” is Spanish and means “ceiling”. The head fins finally brought the animals the name "devil rays".
Giant mantas can reach a span of seven meters and a weight of two tons. In contrast to many other types of rays, they do not have a poison sting. In contrast to their relatives, they usually stay near the surface of the water where they can find their food. Apparently they only spend their rest periods near the ground. Mantas have a head fin on either side of the head. With these fins, they add extra plankton-rich water to their mouths. For a long time it was believed that they only feed on plankton , which they catch while swimming. However, isotope studies of the muscle meat of giant manta rays showed that the giant manta rays also had to eat other foods. Almost 75% of their diet is likely made up of fish and pelagic molluscs . These are likely to be hunted at depths of 200 to 1000 meters.
Like the cow-nosed rays , the giant manta ray uses its fins in a similar way to bird wings. The top speed is 9–12 km / h. Sometimes they jump out of the water. Jumps over 2 meters have already been measured in smaller devil rays.
Giant mantas are distributed worldwide in all tropical oceans in shallow water. They prefer waters near the coast.
Mantas can be found both in the fringes of the Indian Ocean and on the fringes of the Atlantic and Pacific as well as in the adjacent seas such as the Gulf of Mexico. In the western Atlantic, the distribution area extends from the Gulf of Mexico to tropical Brazil. In the Indian Ocean, the distribution extends from South Africa to India. The western Pacific is populated from northern Australia to Southeast Asia and in the area of the oceanic islands. The giant mantas are also at home in the adjoining seas such as the Bay of Bengal, the Red Sea and the Arabian Sea. Mantas can often be found at the cleaning stations in the reefs and are usually accompanied by ship keeper fish.
Mantas are listed on the IUCN red list in the "NT" category. They are not yet considered to be threatened with extinction, but their populations are very sensitive due to the low rate of reproduction.
The giant manta ray is sexually mature when it is five years old. When mating, the male introduces one of his so-called clasps into the cloaca in the female . It takes 13 months for the boy, about 1.9 m wide and 10 kg, to be born. Emergency births in harpooned pregnant females have been observed several times. In June 2007 the first giant manta ray was born in captivity at the Okinawa Churaumi Aquarium . The female, 1.9 m wide, however, died just five days after its birth - it may have been harassed and injured by its father.
Like other very large cartilaginous fish (e.g. whale or basking sharks), manta rays occur in small stocks, grow slowly, become sexually mature late and have a low number of offspring.
In addition to humans, who only fish for mantas to a limited extent worldwide, predatory sharks , including tiger sharks , are among the larger enemies of this species. Humans hunt the devil rays by harpooning. Their meat is considered a local specialty, their liver is rich in oil, and their skin is made into abrasives. Other animals fall victim to drift nets and gillnets. Gradually the hunt for the manta is also gaining commercial interest.
The giant manta ray was described in 1792 by the German naturalist Johann Julius Walbaum under the scientific name Raja birostris . In 1829 the English zoologist Edward Nathaniel Bancroft introduced the genus Manta . Since both the morphological and the genetic characteristics of the genus Manta lie within the range specified for the genus Mobula , the genus Manta was synonymous with Mobula in June 2017 , so the giant manta now has the scientific name Mobula birostris .
Giant mantas and man
The type of movement, appearance and size of the manta rays as well as the name "devil rays" probably contributed to the fact that all kinds of horror tales circulated about them among seafarers in the 18th and 19th centuries. It was therefore previously wrongly believed that giant mantas were dangerous for humans. Most animals even tolerate divers by their side. In March 2013, the CITES Species Conservation Conference in Bangkok decided to regulate the trade in manta rays; the regulation came into force on September 14, 2014.
Keeping in captivity
Giant Mantas are currently only kept in four zoo aquariums around the world, including the Georgia Aquarium and the Okinawa Churaumi Aquarium . In the latter, a baby manta ray was even born in 2007, but died a few days later due to an injury to the pelvic disk. "Animal rights activists blamed the keeping conditions in marine zoos for this".
- Katherine B. Burgess, Lydie IE Couturier, Andrea D. Marshall, Anthony J. Richardson, Scarla J. Weeks and Michael B. Bennett: Manta birostris , predator of the deep? Insight into the diet of the giant manta ray through stable isotope analysis. The Royal Society Publishing, doi: 10.1098 / rsos.160717
- Mobula birostris in the endangered Red List species the IUCN 2006. Posted by: Marshall et al , 2006. Retrieved on 12 May, 2006.
- William T. White, Shannon Corrigan, Lei Yang, Aaron C. Henderson, Adam L. Bazinet, David L. Swofford, Gavin JP Naylor: Phylogeny of the manta and devilrays (Chondrichthyes: mobulidae), with an updated taxonomic arrangement for the family. Zoological Journal of the Linnean Society, 2017, June, 1–26, DOI: 10.1093 / zoolinnean / zlx018
- Cites resolution: Endangered shark and manta ray species should be protected Spiegel Online from March 11, 2013
- Species protection: These sharks must now be better protected by humans. The time of September 12, 2014
- Archived copy ( memento of the original from November 29, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- Spiegel-Online: Death in captivity - Ray baby dies a few days after birth