The mangrove killifish or mangrove rivulus, Kryptolebias marmoratus (formerly Rivulus marmoratus), is a species of fish in the Aplocheilidae family. It lives along the east coast of North, Central and South America, from Florida to Brazil. It is about 75 mm long.
The mangrove rivulus is a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration, National Marine Fisheries Service, has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. Endangered Species Act (ESA).
Scientists have recently discovered that Mangrove rivulus can spend up to sixty-six consecutive days out of water, which it typically spends inside fallen logs, breathing air through its skin. It enters burrows created by insects inside trees where it relaxes its territorial, aggressive behavior. During this time it alters its gills so that it can retain water and nutrients, while nitrogen waste is excreted through the skin. The change is reversed once they re-enter the water.
When jumping on land, the mangrove rivulus does a "tail flip", flipping its head over its body towards the tail end. The rivulus' jumping technique gives it an ability to direct its jumps on land and to make relatively forceful jumps. A team of scientists associated with the Society for Experimental Biology released a video in 2013 showing the jumping technique.
The species consists mostly of hermaphrodites which are known to reproduce by self-fertilization, but males do exist, and there is strong genetic evidence for occasional outcrossing. They are also the only simultaneous hermaphroditic vertebrates, and the concentration of males to hermaphrodites can vary depending on the local requirement for genetic diversity (for example, if there was an increase in the local parasite population, secondary male numbers would increase).
This species is extremely vulnerable to habitat modification and fragmentation, environmental alteration, and human development/encroachment.
- IUCN: Least Concern
- American Fisheries Society: Vulnerable
- Species of Greatest Conservation Need: Florida
Taylor (1999) is the last status review for the species.
- Ong, K. J.; Stevens, E. D.; Wright, P. A. (2007). "Gill morphology of the mangrove killifish (Kryptolebias marmoratus) is plastic and changes in response to terrestrial air exposure". Journal of Experimental Biology 210 (7): 1109. doi:10.1242/jeb.002238.
- "Tropical fish can live for months out of water", Reuters, Wed Nov 14, 2007 9:05pm GMT
- "The fish that can survive for months in a tree", Daily Mail, 17 October 2007
- "Tropical fish can live for months out of water", Reuters, Nov 14, 2007 9:05pm GMT
- Lublnski, B. A.; Davis, W. P.; Taylor, D. S.; Turner, B. J. (1995). "Outcrossing in a Natural Population of a Self-Fertilizing Hermaphroditic Fish". The Journal of Heredity 86 (6): 469–473.
- MacKiewicz, M.; Tatarenkov, A.; Turner, B. J.; Avise, J. C. (2006). "A mixed-mating strategy in a hermaphroditic vertebrate". Proceedings of the Royal Society B: Biological Sciences 273 (1600): 2449. doi:10.1098/rspb.2006.3594.
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