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Neat to know ~ Creature of the week
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The Manta Ray
2020-11-21
– Manta Rays, who get their name from the Spanish word, “manta,” meaning “blanket,” are the biggest rays out there. There are two species of manta ray: the giant manta ray, which is found around the equator in oceans worldwide, and the reef manta ray, which lives near coastlines in the tropical waters of the Indian and Pacific oceans.
– Their shapes are distinctive. They have large wing-like pectoral fins which have extensions on either side of the mouth. These look like devil’s horns, hence the manta ray’s nickname, “Devil Ray.” These giants of the deep are far from devilish, though! They are intelligent drifters, gracefully making their way through the oceans as they feed on tiny plankton and krill. They are not dangerous to humans and have in fact been known to approach divers with innocent curiosity.
Read on to learn more about the gentle manta ray.
Life cycle
- Female manta rays become first-time moms around age 9 or 10. Pregnancy lasts for 12-13 months. A female usually gives birth to one pup at a time, sometimes two. The newborn looks just like an adult manta, only smaller. It has the ability to survive on its own immediately, without any care from its parent. A female manta ray might give birth once every two years.
- Manta rays have a lifespan of 50 years. Giant manta rays spend most of their lives either alone or in small groups that get together to feed.
A giant hunter with tiny prey
- A giant manta ray can weigh up to 5,000 lbs. (2,267 kg). It can have a wingspan of up to 29 ft. (8.8 m). How does it manage to eat enough to sustain its massive size?
- Manta rays have an efficient way of catching their food. They are “filter feeders,” which means that they move through the water with their mouths open to gather food. The fins on either side of their mouths (called the cephalic fins) sweep in zooplankton (tiny organisms found in huge quantities in the oceans, particularly closer to the surface) and krill (tiny crustaceans that live in swarms, found in all the world’s oceans). The manta ray has rows of small gill plates, which filter out the stuff they don’t want to ingest and keep that which they do want to eat. In this way, manta rays don’t have to do much strategic hunting. Their only job is to find where the krill and zooplankton are and open their mouths!
- Sometimes manta rays find a place with lots of food. Several mantas might team up and follow each other in circles, creating a kind of funnel that traps the prey in the spinning water. They then just open their mouths and let their meal flow in. Manta rays have been seen doing somersaults in areas where they find lots of krill. The flips they do, allow them to stay in that one spot and devour everything in sight before moving on.
- When the water doesn’t seem to have much krill or plankton in it, manta rays sometimes stir up the ocean floor to reveal any hidden prey and push it up out of the sand.
Big brains
- Manta rays have relatively big brains. Scientists believe that they are able to recognize themselves in a mirror. This demonstrates a high level of intelligence, also found among primates, elephants, and dolphins.
- They seem to be able to remember the lay-out of an area after they have left it. This demonstrates a long-term memory and the ability to recreate maps of their environment in their brains.
- Manta rays go to “cleaning stations” where smaller fish land on them and eat away parasites and dead skin from their bodies. These stations are near coral reefs. Despite the distances they travel, Manta rays are known to return to the same cleaning stations repeatedly. This is thanks to their ability to make mental maps of their area and remember how to get to specific locations.
Threatened
- Manta rays have a few natural predators, namely, orcas and sharks. But the biggest threat to their continued existence comes from humans. They are currently endangered.
- People kill manta rays for their meat, but also for the gill plates in their mouths. These are seen as a precious resource for Chinese medicine. It is claimed that the gill plates can cure illnesses and improve blood flow. Each year thousands of manta rays are hunted for their plates.
- Many manta rays are killed each year in collisions with boats.
- Climate change and the resulting warming of the oceans is affecting the life cycles of the plankton that manta rays depend upon for food. If the number of plankton dwindles, then manta rays are in trouble.
- The habitat of manta rays is deteriorating. Pollution in the oceans creates toxic waters filled with dangerous debris that kills manta rays.
- Concerned people are recognizing the vulnerable status of the manta ray and are taking action. The Convention on Migratory Species is an agreement among many different countries to protect migrating animals. Manta rays are currently protected under this agreement. Some countries, like Mexico and New Zealand among others, have also banned the fishing of the manta ray. Indonesia discovered that protecting manta rays also pays off. More tourists are attracted to their shores if they can view these remarkable creatures.
Sources: National Geographic, “Manta Rays,” https://www.nationalgeographic.com/animals/fish/group/manta-ray/; Manta Ray World, “Manta Ray Facts,” https://www.mantaray-world.com/facts-about-manta-rays/; Encyclopaedia Britannica, “Manta ray,” https://www.britannica.com/animal/manta-ray.