The glow-in-the-dark shark that fits in your pocket

A team of researchers have identified a new species of pocket shark in the Gulf of Mexico. The unusual elasmobranch sheds light on just how little we really know about our deep oceans.

pocket shark
The new species is based off this single specimen collected from the Gulf of Mexico

For all those people who still think sharks are bloodthirsty monsters of the deep, look away now. The newly discovered pocket shark will haunt your dreams with a frightening length of 5½ inches and the terrifying ability to glow in the dark! Ok… so this little guy is hardly Jaws. But being only the second ever pocket shark to be discovered and being a brand new species makes this mini-menace potentially a lot more interesting. It was initially found by accident in a survey of the deep waters of the Gulf of Mexico in 2010 and left on ice. That was until a new team of researchers stumbled upon it and realised what it was, or at least wasn’t. Being significantly different to the only other known pocket shark the new species has been named the American pocket shark, Mollisquama mississippiensis. Not only is it an extremely interesting and informative find, it also highlights just how little we know about the marine life in our deep oceans.

A rare find

This adorable new species of shark is just the second pocket shark specimen to ever be recovered. The first was discovered in the Pacific back in 1979 by Russian ichthyologist Nikolai Vasilevich Parin, after who it was named Mollisquama parini.  But in 2010 another specimen was captured somewhat accidentally by researchers studying the diets of sperm whales in the eastern region of the Gulf of Mexico. It was collected along with the rest of the anomalous specimens and stored away for future research. That was until Dr Mark Grace from the National Oceanic and Atmospheric Administration (NOAA) came across it whilst examining the collection in 2013.

A more detailed look at the 5 and a half inch specimen

Knowing of its Russian relative Grace decided to take it back to his labs in Mississipi where it could be studied by him and some of his fellow researchers including Dr Henry Bart from Tulane University. After lots of work and multiple different scans and genetic tests it was determined that the specimen was significantly different enough to be its own species. Earlier this year Grace and his team released their findings in a paper in Zootaxa where they also revealed its new title. It was named the American pocket shark, Mollisquama mississippiensis, not after the US but the North American Mississippi River Basin that helps support life in the Gulf of Mexico. According to the team the name was given to recognize the diversity of marine life in the “extraordinary Americas of the Western Hemisphere”.

What is a pocket shark?

Pocket sharks are a type of kitefin shark, a group of slim and flat bodied sharks that stay close to the ocean floor. Although the name ‘pocket shark’ is an apt name for such a small shark it actually has nothing at all to do with its diminutive stature. It instead refers to the two pocket structures, located behind the pectoral fins, that store bio-luminescent fluid. The purpose of these fluids is unkown but are likely to either attract prey or scare off predators. But one of the big differences that made the American pocket shark its own species is the presence of light-producing photophores located across most of its body. This gives it the ability to double-down on its glow in the dark properties and amplify whatever benefit its bio-luminescent fluids give it. Unfortunately we have no real way of seeing how this would look in the wild.

The tiny teeth of the American pocket shark helps to inform us what it might eat

The American shark also differs in size being shorter than its pacific counterpart and having ten less vertebrate. The specimen was believed to be fully grown and also male meaning its 5½ inch length (14cm) is likely to be the max length it can grow to. As they have never been observed in the wild all we can really say for sure about their behaviour is what we can determine from their physiology. For example we don’t know what they eat but their teeth suggest that they are probably bottom feeders. As a result there is still lots we are unsure of and more specimens and observations will be needed to fill in the gaps.

A gulf in knowledge

As well as being an incredibly rare find and a very interesting creature, the discovery of the new American pocket shark also highlights a serious lack of understanding of deep water marine ecosystems. In particular areas like the Gulf of Mexico where there is believed to be a diverse abundance of marine life that we just haven’t managed to discover yet. Dr Bart told Mongabay “the fact that only one pocket shark has ever been reported from the Gulf of Mexico, and that it is a new species, underscores how little we know about the Gulf”. Just last month a NOAA exploration team recorded the first wild footage of giant squids in the area. But as well as what is down there we are also unaware of how we are effecting this ecosystem which is equally as worrying. There is now a fear among scientists that these amazing new species may have been wiped out before we have a chance to discover them.

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