While scientists have theories about how fish first crawled onto land and breathed air , it 's a mystery as to how vertebrates evolved tongues instead of feeding using suction . But now , a slow-motion video of mudskippers eating shrimp may help reveal the evolutionary secret . It shows the creatures , which live in and out of water and forage for food on the ground , taking a mouthful of water to act like a tongue , allowing them to swallow food on land . Scroll down for video . A slow-motion video of mudskippers feeding may help reveal an evolutionary secret . It shows the creatures , which live in and out of water and forage for food on the ground ( pictured in a stock image ) taking a mouthful of water to act like a tongue , allowing them to swallow food on land . Experts believe the finding may shed light on how terrestrial tetrapods - four-legged vertebrates - with tongues evolved from fish between 400 and 250 million years ago . When underwater , mudskippers suck water containing food particles into their mouths , which are swallowed when they reach the back of their throats , New Scientist reported . However , this method doesn ’ t work on land , so terrestrial vertebrates evolved tongues to move the food to the back of the throat . A team of researchers led by Krijn Michel at the University of Antwerp , Belgium , captured slow-motion X-ray footage ( shown ) of Atlantic mudskippers eating pieces of brown shrimp out of water . The video revealed that mudskippers combine the sucking method of fish ( stock image left ) with the grabbing tongue action of amphibians such as nexts ( right ) , meaning they could reveal a missing evolutionary link . Mudskippers are members of the gobies family , which is one of the largest fish families comprising more than 2,000 species . They are completely amphibious that can use their pectoral fins to walk on land . They appear to move in a series of 'skips ' and can use their muscular bodied to catapult themselves two feet ( 60cm ) in the air . Mudskippers are uniquely adapted to intertidal habitats , meaning that they do n't have to hide in rock pools or retreat when the tide goes out . They feed out of water and even fight to defend their territories . The creatures breathe through their skin and the lining of their mouth and throat , but this only works when mudskippers are wet , limiting them to humid and watery habitats . Enlarged gill chambers enable them to retain a bubble of air and they close tightly when the animal is out of water to keep gills moist . A team of researchers led by Krijn Michel at the University of Antwerp , Belgium , captured slow-motion X-ray footage of Atlantic mudskippers eating pieces of brown shrimp out of water . They found that it takes the gelatinous creatures less than half a second to pounce and eat . By watching the video , which was slowed down 50 times , the experts were able to see that the mudskippers carry water in their mouths . They spit it forward to grab the shrimp and then suck it back into their mouths quickly , to mimic the action of a tongue . The team also placed food on an absorbent surface and found that the mudskippers could still grab the food using their unusual technique , but had problems swallowing it . The scientists worked out that mudskippers move the hyoid bone in the floor of their mouth upwards , before they attempt to gulp down food . Their finding is reported in Proceedings of the Royal Society B : Biological Sciences and is the opposite of what fish do underwater . However , it closely resembles the feeding habits of newts , which have tongues . This means that mudskippers combine the sucking method of fish with the grabbing tongue action of amphibians , so they could reveal a missing evolutionary link . Dr Michel said : ‘ This could be an in-between , from which a fleshy tongue could have evolved . ‘ This has never been considered a possibility , until now .
Slow motion video captured by University of Antwerp researchers shows mudskippers eat on land with the help of a glob of water . Amphibious creatures take a mouthful of water that acts like a tongue . Find could help solve the evolutionary mystery of how tongues evolved .