Stomach bacteria of elasmobranchs

The gastrointestinal microbiome is the collection of all bacteria and microorganisms living in our stomachs and intestines, as well as in those of many animals, such as sharks and rays. These bacteria are crucial as they aid sharks and rays in digesting their food and maintaining health, while also stimulating the immune system. Given that elasmobranchs have a relatively simpler digestive system compared to other animals like humans, these bacteria are even more critical for their well-being.

What’s interesting is that the quantity and variety of bacteria can vary from one species of shark or ray to another. This can depend on what they eat as well as where they live.

In a project we conducted in the Gulf of California, Mexico, we used DNA sequencing technology to identify different types of bacteria in the stomachs of four species of sharks and rays. And we made a fascinating discovery: some families of bacteria found in these elasmobranchs have the ability to break down molecules like collagen and chitin, which are found in the skin of fish and in the skeletons of crustaceans. We showcase some examples in the following infographic.

Infographic of the Stomach bacteria of elasmobranchs. Image © Miguel A. Tripp Valdez

Now, our next step is to delve deeper into the types of bacteria present in each species and to investigate whether there’s any relationship between certain bacterial groups in the stomachs of sharks and rays living in contaminated areas.