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Manta Ray

October 21, 2015 in Uncategorized

Dharavandhoo_Thila_-_Manata_Black_Pearl

Picture of a manta ray showing the big triangular pectoral fins credit: Shiyam ElkCloner

The manta ray (Manta birostris) is one of the largest rays to belong to the Myliobatidae family, growing up to 7 metres in length. Manta rays are classed as Elasmobranchii, along with sharks, but they don’t share the same family as manta rays are part of the Myliobatidae family.

The manta ray is much larger in comparison to most other rays as they have two large triangular pectoral fins allowing the manta ray to move through water by the wing like movements from the pectoral fins, causing water to be driven backwards (Deakos, Mark R. 2010). Manta rays also have two cephalic fins located on the head of the ray in front of both eyes, the cephalic fins are horn shaped in nature and can be rolled up, when the ray is swimming, and can be rolled down, when the ray is searching for food (http://www.mantaray-world.com/manta-ray-anatomy/).

Despite the giant size of the manta ray, the primary source of food for the ray is tiny planktonic organisms. The manta ray is able to feed off tiny planktonic organisms due to the ray constantly filtering water through its mouth. The planktonic organisms are then filtered from the water passing into the mouth using gill rakers, sponge like tissue around the gills capable of filtering water passing through the gills. Whilst the manta ray is searching for food the cephalic fins unravel and are used to direct more water into the mouth whilst searching for food. Manta rays often swim along a sea bed whilst searching for food often scooping up plankton from along the sea floor. Manta rays only have a handful of predators including large sharks and orca (http://www.mantatrust.org/) (http://www.elasmo-research.org/index.html).

The mating process in manta rays is initiated through the formation of a “mating train”; several male manta rays following a single female competing for the right to mate, this courtship can last several days. One of the male manta rays then grabs the tip of the female’s pectoral fin with its teeth and the pair mate belly to belly. Fertilized eggs then remain in the female rays for up to 12 months. The eggs then hatch internally so the female ray ends up giving birth to live young. Generally the manta ray only gives birth to one or 2 pups at a time. These new born manta rays are an impressive 1.2-1.5 metres across. The manta ray doesn’t reproduce quickly with births taking place only once every 2-5 years. (http://www.flmnh.ufl.edu/fish/Gallery/Descript/MantaRay/MantaRay.html) (http://www.mantatrust.org/) (http://www.elasmo-research.org/index.html).

Manta rays are generally found in tropical, sub-tropical and temperate waters in the major oceans of the world and has been sighted as far north as new jersey and as far south as South Africa. Generally the manta ray is found between the latitudes of 31 degrees North and 36 degrees South. The manta ray is believed to travel vast distances across the ocean and is a seasonal visitor to various coastlines and offshore sites, this shows the manta ray to be more of an oceanic species than other rays such as the reef manta ray. (http://www.iucnredlist.org/) (Marshall, A.D., Compagno, L.J.V. and Bennett, M.B. (2009) Redescription of the genus Manta with resurrection of Manta alfredi (Krefft, 1868) (Chondrichthyes; Myliobatoidei; Mobulidae). Zootaxa, 2301: 1-28.)

 

 

1 response to Manta Ray

  1. Great stuff James! Interesting article, lots of references used, but not all mentioned at the end or with correct source attribution. That’s something for us to work on. Try to be more focussed, your article is very broad and doesn’t go into great detail on anything. But as a general introduction to the Manta Ray, it is an interesting read.

    Some minor comments:

    1) Try to use a stronger title, something to capture imagination or readers to it. Just Manta Ray is a bit bland, doesn’t tell me what to expect from your article.

    2) Your opening paragraph fails to attract me to read the rest of your article, it is a bit heavy and slightly disorganised, I would start off saying largest rays…, same major group as sharks and stop there. Here you need to end with what this article is about, i.e. this article will introduce the general biology of the Manta Ray…etc etc, tell the reader what to expect.

    3) The writing in the second paragraph could be more focussed, as it could throughout. Your link sentences often repeat and often you are lacking data, i.e. what exactly is the function of the cephalic fins? You never say this. I assumed feeding? But that leads to ambiguity.

    4) Giant size, this is an ambiguous term, I would bring that down, and mention here the 7m size and the size of it’s planktonic prey, this gives you a stronger sense of scale and a more robust argument.

    5) In the feeding paragraph, you are repeating the unravelling of the cephalic fins again, this is a waste of text, and should be removed. Try not to repeat oneself.

    6) Manta rays only have a handful of predators, OK, what is the mortality rate from predation? Rare? Try to get some more quantification in rather than just saying something.

    7) Impressive 1.2-1.5 m, not to a giraffe it’s not, try to avoid using massive, impressive, giant etc. Stick to the facts, compare this to a shark or a closely related ray species to give a sense of scale.

    8) The geographic distribution para should go towards the top of your article to help it flow better.

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