The Atlantic Mudskipper are primarily carnivorous benthic feeders that feed using a suction and small sharp teeth. Their opportunistic feeders with a preference of insects, crustaceans, polychaetes (worms), and small fish.

Suction and the “Water Tongue”

On Land the Mudskippers have the unique ability of what some to refer to as a “water tongue” first it covers its prey with its mouth the submerges that pray in water from its buccal cavity in the mouth. Creating a suction force within its mouth by expanding the volume sucking up the water within its mouth into its body. Study shows the buccal water is necessary for the prey to be caught.

However it’s a different case when feeding in water, as they have specialized muscles to open their gill openings. They use this to pump water out of their gill cavity outwards then lowers its jaw and slowly expands the back of its mouth larger than on land creating a stronger suction, as to prevent releasing water that would normally push prey in an aquatic environment.

Truth about that The True Stomach

Curiously about the Goby Family is that they do not have what is considered a “true stomach” in the gastrointestinal tract where there’s a widening in the anterior position containing a gastric gland for storing and dissolving food. Mudskippers being part of the subfamily Oxudercinae in the Gobiidae family were assumed to also lack a true stomach due to their association with their ‘stomachless’ family for a while. Two characteristics they share with other animals that don’t have or need a developed stomach were also seemingly evidence as to why they wouldn’t have or need a true stomach. One being the fact they contain a set of pharyngeal teeth located in their throat used for grinding up food, which functionally overlaps with true stomachs. The second trait is their feeding behavior of eating small amounts of food in a short amount of time, is a habit that doesn’t necessitate a true stomach unlike in animals that eat larger amounts of food for a longer amount of time. However with lack of research that would conclusively declare them as having or not having a true stomach and the trend of carnivorous animals utilizing a true stomach, research has examined the gastrointestinal tract of the Atlantic Mudskipper.

(Wołczuk et all, 2018) A sketched diagram of the Atlantic Mudskipper’s track.

The study did find that they did evolve to have a true stomach, and utilized this feature to. Though it is a relatively, simple and smaller stomach, as well as having lower amounts of digestive proteins to fit its feeding behavior A trait unique to a true stomach and further differentiated the gastrointestinal track from the rest of their taxonomical family was that gastric glands. Mudskipper gastric glands were densely packed and distributed specifically in the lining of the stomach as opposed to other gobies more widely distributed and less concentrated gastric glands. These glands found in the Mudskipper’s true stomach were packed with cells that contain large amounts of mitochondria, and smooth membrane that secretes hydrochloric acid. To protect themselves from its own hydrochloric acid, neutral mucus was lined all across the stomach, something other gobies didn’t possess which not only prove that Mudskippers have a true stomach, but they also use it as well.

A section of note within the gastrointestinal track was the oesophagus. Analyzed results of the oesophicus shows that there are numerous tracks of goblet cells that produce both acid and neutral mucus. This is a mechanism that helps it swallow solid material easier while also indicating the ability to adapt the ability to different kinds of prey easier, which would be helpful since the Mudskippers has two different sets of food from different habitats (aquatic and terrestrial). Interestingly not only do the mucus produced by Goblet cells help protect with hydrochloric acid, but they’re also studied to help with ion regulation indicating their GI tract may have an important role to how they’re able to adapt to wide ranges of salinity.