#synbranchiformes

Fire Eel (Mastacembelus erythrotaenia), family Mastacembelidae, order Synbranchiformes, found in freshwater habitats in SE Asia

This species is not a “true eel”, but is in a group called the spiny eels.

Think all eels live in water? Think again! In 2018 scientists described a new species of swamp eel which they believe resides almost entirely on land. The eel, dubbed Rakthamichthys rongsaw, is bright pink and has extremely tiny, almost non-functional eyes; a result of its subterranean lifestyle depriving it of the need for sight or pigment. Only one individual has been found in north-east India, so the extent of its distribution is currently unknown.

(Sources - 1, 2, 3, 4)

Order: Synbranchiformes

Common Name: “swamp eels”

Families: 4 - Synbranchidae (“swamp eels”), Chaudhuriidae (“earthworm eels”), Mastacembelidae (“spiny eels”), and Indostomidae (“armoured sticklebacks”)

Anatomy: long, eel-like body; poorly developed gills with small openings; dorsal and anal fins are low and continuous around the tail tip; no pelvic fins; no or very small scales; no swim bladder

Diet: crustaceans, worms, amphibians, small fish, turtle eggs

Habitat: tropical parts of America and Africa, southeastern and eastern Asia, East Indies, and Australia; most species live in swamps, caves, and sluggish fresh and/or brackish waters

Evolved in: possibly Late Cretaceous, but no synbrachiform fossils are known

Propaganda under the cut:

Synbranchiformes. This order is made up swamp eels, which are eel-like but have spiny rays in their fins.

Gobiiformes. This order is made up of gobies, some of the smallest fish there are.

Fire Eel (Mastacembelus erythrotaenia), family Mastacembelidae, order Synbranchiformes, found in freshwater habitats in SE Asia

This species is not a “true eel”, but is in a group called the spiny eels.

Asian Swamp Eel aka Rice Paddy Eel (Monopterus albus), family Synbranchidae, order Synbranchiformes, found in East and SE Asia

Swamp eels get the best of both worlds in just about everything! They feed readily on animals, plants, and carrion. They have gills to breathe in water, and thanks to the high number of blood vessels present in the mouth and throat, most species are also able to breathe air, and can even move across land to find new bodies of water. Lastly, many species are also protogynus, beginning their lives as female and transitioning to male as they get older.

Spiny Eels, family Mastacembelidae, order Synbranchiformes, found in fresh water environments in SE Asia

L - Black Pearly Eel (Mastacembelus notophthalmus) R - Panther Eel (Mastacembelus pantherinus)