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Why do Animals have Stomachs?

Why do Animals have Stomachs?



The appearance of the stomach marks an important step in vertebrate evolution, dating 370 million years ago. Before this time, animals did not have an acidic stomachs.

Surprisingly, some creatures naturally lost their stomachs. Goldfish and platypus are examples of such creatures. They can still digest food because digestion mainly happens in the intestine in all animals. However, scientists do not know how digestion changes when there is no acid in the stomach to help the process.

The stomach is commonly thought of as a sac-like structure, but its function transcends that of mere storage.  The stomach holds food so that digestive enzymes can begin to break down food for nutritional absorption by the intestine. It also helps in stopping pathogens from entering and infecting the intestine. The stomach does all of this by producing acid that activates enzymes that break down food. The stomach acid is produced through the action of a proton pump.

How important is the stomach? How does it contribute to the efficient digestion and absorption of nutrients? How does it help the animal grow?

I like to think that the best way to see exactly how important something is, is to take it out, unplug it or shut it down and see what happens. And that is what I am doing in my research

In my PhD research, I am working with Dr. Jonathan M. Wilson, in the Department of Biology at Laurier, to create genetically modified fish that do not have the gastric proton pump, and thus, lack the capacity to produce acid and begin to digest food in their stomachs.

These transgenic fish will help us understand what changes in the pathways that lead to nutrient absorption further down in the gut (intestine) when there is no gastric acid production. We are particularly interested in finding out:

  • Will the absorption of nutrients in the intestine be impacted because that may compromise the growth and survival of the fish?
  • Will it affect satiety and food consumption?
  • What effects will a missing stomach, as a site of the beginning of digestion, have on an organism?

Knowing how these mutant fish change in growth, intestinal absorption, and digestion will allow us to understand what special adaptations exist in the body of the animals that lack a stomach, to make them able to grow and meet their body energy requirements.

This research will help scientists understand digestion, and hopefully, in the future apply these findings to understanding how animals who have lost their stomachs are able to thrive without one.

 

About Patrícia

Patrícia Ferreira is a comparative physiologist who is pursuing a PhD in Biological and Chemical Sciences at Wilfrid Laurier University. To address her research questions, Patrícia creates knockout models in fish (and previously in mice) that target specific genes/proteins to better unveil their function and mechanisms of action.

She has been awarded two Ontario Graduate Scholarships and the Laurier Centre for Women in Science Hypatia Award for Women in Science. She holds a bachelor's degree in biology and a Master of Science degree in Marine Sciences from the University of Porto, Portugal.

 

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