Mangrove rivulus: Rivulus marmoratus
Genus/Species: Kryptolebias marmoratus
Common Name: Mangrove rivulus
Federal Status: Not Listed
FL Status: Not Listed
FNAI Ranks: Not ranked
IUCN Status: LC (Least Concern)
Mangrove rivulus are the only member of the rivulus family that occurs in North America (Taylor and Snelson 1992). This species can reach a body length of 2.4 inches (6.1 centimeters). Mangrove rivulus are olive-colored with a flat back body, rounded tail fin, and small black dots located throughout the body surface (sometimes) (National Oceanic and Atmospheric Association 2009).
The diet of the mangrove rivulus primarily consists of worms, copepods (small crustaceans), mosquito larvae, and their own eggs when held captive (National Oceanic and Atmospheric Association).
Mangrove rivulus are self-fertilizing hermaphrodites (have both male and female reproductive organs), which makes them the only known vertebrate to practice this style of reproduction. However, a small non-hermaphroditic population has been discovered in Belize. Eggs hatch two to four weeks after being laid (National Oceanic and Atmospheric Association 2009).
Habitat and Distribution
The mangrove rivulus inhabits mangrove forests from southeastern Brazil through the Antilles and Central America to Florida (Taylor 1999). In Florida, this species is found on the Atlantic coast from the Keys to Volusia County and from the Keys to Tampa Bay on the Gulf Coast (Taylor 1999, Briggs and Brown 1986, S. Taylor pers. comm. 2012). They are an amphibious/fossorial species (they are capable of living on land and water, burrowers on land). Most of their time is spent on land where they can be found hidden in rotten wet logs or under moist leaf litter (Taylor et al. 2008).
The main threat to the mangrove rivulus is the destruction and fragmentation of mangrove habitat caused by development, encroachment, and mosquito control (National Oceanic and Atmospheric Association 2009). Other threats include habitat pollution from pesticides (Taylor 1999).
Conservation and Management
The mangrove rivulus is protected from take by 68A-4.001, F.A.C.
Florida’s Endangered and Threatened Species Rule .
Biological Status Review (BSR)
Supplemental Information for the BSR
Species Action Plan
Other Informative Links
International Union for Conservation of Nature
National Oceanic & Atmospheric Administration
Smithsonian Marine Station at Fort Pierce
Printable version of this page
Briggs, J. C. and Brown, J. E. 1986. Effect of reditching mosquito control ditches on the fish community of the mangrove habitat in Tampa Bay, Florida. Report to Pinellas County Mosquito Control District. 10 p.
National Oceanic and Atmospheric Association. (2009). Mangrove rivulus. Retrieved April 21, 2011, from NOAA National Marine Fisheries Service.
Taylor, D. S. 1999. Rivulus marmoratus status review: consideration for listing under the Endangered Species Act. National Marine Fisheries Service. Final Report. 46 p.
Taylor, D. S., Turner, B. J., Davis, W. P., and Chapman, B. B. 2008. A novel terrestrial fish habitat inside emergent logs. American Naturalist 171(2):263-266.
Image Credit FWC