Manta giving birth or intestinal eversion?

By Angelina Cecchetto on 9 February 2013

Photography: ©2013 Martin Ureta. All Rights Reserved.

Photography: ©2013 Martin Ureta. All Rights Reserved.

Following the great feedback I received from the last post “The first breathtaking photo of a giant oceanic Manta Ray giving birth??” it would seem that the picture could well show a case of what is called “gastro-intestinal eversion” where the manta actually ejects the lower part of its intestine out of the cloaca in order to clean its intestine from indigestible debris.

This is an event which has so far been rarely recorded in the wild. One other case has been recorded in 2007 at a cleaning station in waters off Maui[1].

Since I am no marine biologist I will leave it to the specialists to decide whether the picture shows a manta giving birth or everting its intestine. In any case this is a very rare and lucky shot!

What this information leads me to wonder is whether the regularity at which the mantas evert their intestine has been increased by the anthropogenic pollution factor? It would also be interesting to know what sort of impact this has on the mantas habits and behaviors if any.

It would also seem that the shot could be of a Manta alfredi rather than Manta birostris, this is still to be defined with other shots. The differentiation between Manta alfredi and Manta birostris is fairly recent and dates back from 2009[2]. In fact Manta alfredy, also known as Reef Manta Ray and Manta birostris are both part of what is called the “genus Manta” family and they can easily be confused. It would seem that manta birostris do not display markings between the gills.

What is pretty certain is that the situation of the mantas alfredy is also critical. The same over fishing threats apply to both species and the population is drastically decreasing. The IUCN[3] categorized the manta rays as “Vulnerable” in between the “Near Threatened” and “Endangered” species and states that “Overall, the rate of population reduction appears to be high in several regions, up to as much as 80% over the last three generations (approximately 75 years), and globally a decline of 30% is strongly suspected.”

As I mentioned in the previous article, there are various factors that led to this critical state of affairs: overfishing, very low fecundity rate and anthropogenic pollution.  It would seem that in the wild female mantas give birth to a single pup every 2 to 3 years cycle. When we add this factor to the overfishing trends we can easily understand that populations are being easily depleted.

Whether this picture shows a Manta birostris or a Manta alfredi and whether it is showing a birth or a gastro intestinal eversion (I leave it to the knowledgeable marine specialists and scientists to decide), the important message is that Mantas are in danger and they need a strong global protection. I am hoping that this picture will raise awareness, open up discussions, ideas exchange and humbly contribute towards global mantas protection.

Angelina Cecchetto

[1] “Intestinal eversion in a free-ranging manta ray” by Springer-Verlag 2007. http://www.himb.hawaii.edu/sharklab/Clark_et_al_manta%20intestine%20eversion.pdf

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