''Synbranchus marmoratus'', the marbled swamp eel, neotropical swamp eel, marmorated swamp eel, mottled swamp eel, zange, or muçum is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

swamp eel The swamp eels (also written "swamp-eels") are a family (Synbranchidae) of freshwater eel-like fishes of the tropics and subtropics. Most species are able to breathe air and typically live in marshes, ponds and damp places, sometimes burying them ...

native to

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

, including the island of

Trinidad Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...

and Grenada .

Description

The marbled swamp eel has an elongated cylindrical body and can grow to a maximum length of about , although a more normal adult length is . The dorsal and anal fins are vestigial and the paired pectoral and pelvic fins are missing altogether. The lining of the mouth is rich in blood vessels and provides an additional surface for gas exchange when the swamp eel breathes air.

Ecology

When in water, the marbled swamp eel is able to use its fully functional gills to breathe, whereas on land it can breathe with the lining of the mouth and pharynx. It is a nocturnal predator and feeds on any small prey in its environment such as frogs, tadpoles,https://sta.uwi.edu/fst/lifesciences/sites/default/files/lifesciences/documents/ogatt/Synbranchus_marmoratus%20-%20Swamp%20Eel.pdf fish, spiders, insects and other invertebrates. It moves through dense vegetation on river banks, searches shallow water areas for prey and descends into burrows to find concealed animals. When on land it lives in a burrow, and tunnels more deeply as the ground becomes drier so as to keep below the water table. In the laboratory, these eels have remained alive in drying-out burrows for over six months, moving about through the tunnels. The marbled swamp eel is one of the few fish found up-river of large waterfalls and is a major predator of

tadpole A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found i ...

s in locations that other fish cannot access. It is a

sequential hermaphrodite Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...

, and this is an advantage when it colonises new areas or encounters severe habitats. Juvenile fish can be either male, known as a primary male, or female. Females transition into male fish, known as secondary males, at a length of between . Secondary males can be told from primary males by examination of their gonads. The male digs a burrow and guards the nest.

References

{{Taxonbar, from=Q2403789 Synbranchidae Fish described in 1795