It's been an mystery for centuries, how isolated water bodies can be populated by fishes. But recent research shows a very interesting side of fish eggs. Orsolya Vincze, an evolutionary biologist at the Centre for Ecological Research in Debrecen, Hungary got the merit for this research. Vincze says,
Birds' feathers, feet and feces can spread hardy plant seeds and invertebrates. But since many fish eggs are soft, researchers didn’t expect that they could survive a bird's gut.
When eaten by ducks or other birds as food, most of the fish eggs get destroyed by stomach acids. But a few eggs can still survive in a duck's excrement, possibly helping to spread those fish, including invasive species, to totally different places.
In the lab, Vincze and her colleagues fed thousands of eggs from two invasive carp species to eight mallard ducks. About 0.2 percent of ingested eggs, 18 of 8,000, were intact after defecation, the team found. Some of those eggs contained wriggling embryos and a few eggs hatched, the team reports June 22 in the Proceedings of the National Academy of Sciences. It's not clear yet whether eggs survive in this way in the wild.
A single carp can release hundreds of thousands of eggs at a time. And there are huge numbers of mallards and other water birds throughout the world who feast on those. Migratory ducks could travel hundreds of kilometers before excreting those eggs. So there is a good chance that some lucky fishes can see a whole new country once in a while.