Those are Jumping Fish, Not Flying Fish
A relatively recent article was published by Noah Bressman, Stacy Farina, and Alice Gibb on the importance of how mummichogs can move (Bressman et al., 2016). Mummichogs, known scientifically as the Fundulus heteroclitus, is a fascinating aquatic creature that can travel in the sea and breathe the air around us and move on land (Teo & Able, 2003). To the average Ichthyologist, that does not seem very shocking; other creatures like the Cyprinodontiformes, for example, can do the same (Bressman et al., 2016). However, the way they do it is the fascinating aspect of it and the central point of the paper. It is a complex set of movements in coordination to gauge where they are and where they want to go. This collaboration of multiple senses (visual from the fish’s eyes and touch from its body) to travel is so prominent and unique.
The actual movement is consistent with a tail flip jump but requires a couple of unique steps. The Mummichog needs to prep their bodies after the first thrashing jump by moving upright to be in a proper prone position to perform subsequent tail flip jumps. They also perform several rotations vertically and laterally to adjust and aim towards wherever they want to go, whether it be towards the sea base or to travel more of the land. The study done by Mr. Bressman and his colleagues showed that these jumps would reach up to 10 cm high vertically and 20 cm long horizontally (Bressman et al., 2016). The fish quickly reached the water (40 cm) away in as little as two jumps.
That jump requires another aspect to succeed, the Mummichog’s ability to visually discern a target location. In the study, the fish in a light-based experimental environment was able to see and go towards the water 40 cm away (Bressman et al., 2016). They found that light is a significant factor in how well the fish can travel to its internally designated location. If there is no light, then the fish will not know where it is going and jump in whatever direction it sees fit. If there are no sunny skies, then the Mummichog will literally “flop like a fish.” The ability to perform a complicated jump requires looking before you leap and knowing where you want to go.
The final aspect that ties the Mummichog’s peculiar movement is their one-of-a-kind ability to use visual cues to guide their jumps toward the water. The study found that more fish would jump toward the foil when they covered bodies of water in foil (Bressman et al., 2016). The fish use the light being reflected in the water to guide where they want to go. The more intense the reflection, the more likely they want to go towards it.
The Mummichog is a fascinating fish in its unique properties in how it travels from land back to sea. Its movement is a wondrous collaboration between visual and physical senses that have not been seen in other types of fish. The only question remaining is how the fish evolved to develop this specific jump and toned eyes for reflection off the water. Ichthyologists must do more scientific research to find the origins of this fantastic way of movement in a fish.
References
Bressman, N. R., Farina, S. C., & Gibb, A. C. (2016). Look before you leap: Visual navigation and terrestrial locomotion of the intertidal killifish Fundulus heteroclitus. Journal of Experimental Zoology Part A: Ecological Genetics and Physiology, 325(1), 57–64.
Teo, S. L. H., & Able, K. W. (2003). Habitat use and movement of the mummichog (Fundulusheteroclitus) in a restored salt marsh. Estuaries, 26(3), 720–730.
