There is something magical about small things. While hooking a striper is certainly thrilling, scooping up a tiny shining fish with a hand net is exciting in a different way. You can put it in a bucket and look at it up close – its finely spined fins and smooth body. One of my favorite tiny fish to catch is also a pretty common one – the mummichog. As is the case with many common species, mummichogs have many alter egos – mummies, killifish, gudgeons, chubs, mud dabbler and mud minnows are just a few of their many other identities.
Their scientific name, Fundulus lineolatus, aptly describes them. They are lovely little olivey colored fish that feed on the bottom (Fundulus) in shallow coastal waters and have black lines (lineolatus) on their sides. They have rounded fins and are usually no bigger than a few inches. They also have a bit of an underbite if you look closely – their lower jaw specially designed to “dabble” in the mud. They eat just about anything from bits of plant material to tiny crustaceans – and sometimes even each other. Although, most of the time, the school together rather than eating each other, an homage to their common name, mummichog, which means “going in crowds” in Narragansett.
Despite their small size, mummichogs are quite hardy. That’s one of the reasons they can live in shallow waters where conditions can change drastically. For example, they can survive in temperatures from ranging from 43-95 F. When it gets too cold, they burrow into the mud several inches deep until temperature warm up again. They can tolerate salinity ranges from quite fresh to very salty as well. And, they can somehow gather enough Oxygen out of the water even when there isn’t much Oxygen in it. When there really isn’t enough, they can actually breathe air, coming to the surface to gulp oxygen out of the air, a rare capability for a fish. Lastly, they are somehow resistant to lots of common environmental pollutants like heavy metals and dioxins present in industrial areas. All of this means that they can live in a large variety of habitats from estuaries to marshes to tide pools all along the Atlantic coast and up into Canada.
So, if they are so adaptable and common, are they useful to us aside from being part of the coastal ecosystem? They’re not great for eating, but lots of sport fish like to eat them, making them an important source of bait. Aside from that, they have been used to help control mosquito populations, as they like to eat their larvae. They have been also been used in lab experiments to help understand how they are able to survive such a wide range of environmental stressors. Their entire genome has been sequenced, which means that scientists can understand genetic changes that might occur in response to different toxins.
But, most interesting, perhaps, is that mummichogs are the first fish to be sent into space. They traveled in a plastic bag aboard the Skylab, the United State’s first space station, back in 1973 to see how they would react to conditions in space. They apparently repeatedly swam in little circles, likely the result of having no sense of gravity to otherwise guide them. But, after just a few weeks, they had already adapted to the new conditions and swam normally. Even their eggs hatched normally in space – 48 of 50 that had been bagged up on earth and flown nearly 300 miles up into space. That’s a pretty exciting journey for fish that typically only live to be four years old.
The thrill of hooking a striper may trump watching a tiny mummichog wriggle in a net. But, there is much to learn from these small creatures that are so well adapted to change.
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