The mangrove killifish or mangrove rivulus, Kryptolebias marmoratus (formerly Rivulus marmoratus), is a species of fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 in the Aplocheilidae

Aplocheilidae

Aplocheilidae are a family of bony fishes containing about 15 species. Formerly, the name "Aplocheilidae" was used for the Aplocheiloidei as a whole, i.e. including the Nothobranchiidae of Africa and the mainly South American Rivulidae as subfamilies. This obsolete system is sometimes still seen,...

 family. It lives along the east coast of North

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, Central

Central America

Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 and South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, from Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

 to Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

. It is about 75 mm long.

The mangrove rivulus is a U.S. National Marine Fisheries Service

National Marine Fisheries Service

The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...

 Species of Concern. Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration

National Oceanic and Atmospheric Administration

The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...

, 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).

Ecology

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 inside the trees created by insects where it relaxes its territorial, aggressive behavior. During this time it alters its gill

Gill

A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s so that it can retain water and nutrients, while nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 waste is excreted through the skin. The change is reversed once they re-enter the water.

The species consists mostly of hermaphrodites which usually reproduce by self-fertilisation, but males do exist, and there is strong genetic evidence for occasional outcrossing.

Conservation

This species is extremely vulnerable to habitat modification and fragmentation, environmental alteration, and human development/encroachment.

Conservation designation

• IUCN: Least Concern
• American Fisheries Society: Vulnerable
• Species of Greatest Conservation Need: Florida

External links

• IUCN Red List: Rivulus marmoratus.
• NMFS: Species of Concern Fact sheet
• Grupo Rivulus