Tuesday, 31 March 2015

Manta Ray

These gentle giants of the ocean are very interesting creatures. Not only are they intelligent, they are also the largest of all the rays with the Giant Oceanic Manta Ray being the biggest. They also have their very own cleaning service.
The Manta ray is a large eagle ray, with a flat body and sizes ranging from 5.5m (18ft 1in) to 7m (23ft) wide. The length is usually about half the width, and they can weigh as much as 1350kg (2980lb). They have triangular pectoral fins, broad heads and horn shaped fins (cephalic) on either side of their mouths. They also have a skinny tail which does not have skeletal support and is shorter than their body. They are usually a black or dark colour on the top of their body and white or pale colour with distinctive black markings on the underside; these marks are how they recognize each other. There is mucus that covers their body to protect them from infection. They look like stealth bombers of the sea!
Even though the manta ray is a cousin of the shark they are filter feeders and eat only zooplankton in the form of shrimp, krill and planktonic crab. In one week they eat about 13% of their weight in zooplankton ~ 175.5kg (378.4lb) which is a lot considering they are so small they are invisible to the naked eye. When hunting, the manta ray will swim slowly with its mouth open around its prey and make them form into a dense ball, then swim through the ball and swallow as much as it can. If it is particularly dense they will somersault through it. It is very enchanting to watch as it looks sort of like they are dancing. Manta rays are preyed upon as well by large sharks, killer whales and parasitic copepods. They have also been known to be bitten by the cookie cutter shark.
When it comes to the parasites they have a very cool way of dealing with them. In coral reefs they will swim very slowly so they appear to have stopped and smaller fish will get close to them, eat their parasites and dead skin, or clean out wounds. Different fish do different jobs. If there are multiple rays they will swim around each other and create a queue with the dominant rays in the front, similar to elementary school line ups. They will make multiple passes through the car wash or “ray wash” until they are happy with their services and maybe even tip! They have been known to visit the same reefs more than once giving the impression they keep cognitive maps of the ocean and where certain reefs are. I bet they are frugal and try to return to the cheapest reefs. There is a remora fish which has a flat sort of barbed head that acts like Velcro on the manta rays skin and they hitchhike on them, the gentle manta ray does not mind them.
The manta ray is also considered to be very intelligent; they have the largest brain to body size of any fish and we are still discovering the limit of their smarts. They can tell humans apart by their faces and will bond with certain people more than others. They do enjoy playing with us and will take you for rides when you hold on to their big fins. They have discovered this because some manta rays will get used to a diver and will be very friendly with them but if that same diver were to hide his face in the mask the manta ray will be shy or nervous around the “new” diver.
Manta rays have known to take as long as ten years to mature and when they mate they gestate for about one year ending in a live birth of one or two pups. The new born pup is ready to survive on its own and there is no more needed parental care. I guess they do not collect childcare bonuses then.
Manta rays used to be called devils of the seas and sailors used to consider them a bad sign if they saw one while at sea and an even worse sign if one jumped (or breached) into your boat. Although they have been known to jump in boats (we believe the breaching is a method to remove parasites) they have never been known to attack humans. They have only been known to curiously swim around us and playfully bump into us. They always remember that humans are friends not food. It also goes to show that just because something looks scary does not mean it is.
Manta rays are considered at risk and since 2011 are strictly protected in international waters. Over time more and more places are banning the fishing of them as people use them for food and many other things as well. In 2014 Indonesia put a ban on fishing them as studies show that purchasing a dead manta ray costs $40 but a live one for a tourist to swim with costs $500 and can bring one million dollars of tourism during their lifespan (which is around 50 years).
Manta rays are big, look like stealth bombers, are intelligent, have their own natural self-sustaining ray wash, and are big time money makers! Of course I would consider the manta ray to be an EPIC CREATURE OF THE MONTH!

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