Western Lesser Siren

Photo of researcher holding a gilled siren
Scientific Name
Siren intermedia nettingi
Sirenidae (sirens) in the order Caudata (salamanders)

The western lesser siren is an eel-like, permanently aquatic salamander with external gills, small eyes, small forelimbs with four toes, and no hind limbs at all. The 3 pairs of external gills are red or grayish red and have a bushy appearance. Body color varies from dark gray to brown to almost black. The belly is lighter than the back. Tiny dark brown or black flecks or spots are usually scattered over the back. There are 31 to 38 costal grooves (vertical grooves on the sides of the body). Sirens produce a large amount of mucus on their skin. This, plus their ability to wriggle and squirm, makes them almost impossible to hold. They do not bite and are completely harmless to humans.

Similar species: The three-toed amphiuma (Amphiuma tridactylum) lacks feathery external gills and has forelimbs and hind limbs; in Missouri, its range is limited to the Bootheel. Both of these salamanders can be distinguished from eels and lampreys (which are fish) by their limbs with fingers, tiny eyes, and lack of fins and scales.


Length: 7–16 inches. Potentially to nearly 20 inches. Males are generally larger than females.

Where To Find
Western Lesser Siren Distribution M

Along the eastern edge of the state, near the Mississippi River, and in southeastern Missouri.

This permanently aquatic eel-like salamander lives in a variety of permanent to semipermanent wetlands, including sluggish streams, ditches, ponds, sloughs, and swamps. By day it hides under clumps of aquatic plants and submerged roots or branches. It forages at night.

If the pond or slough begins to dry up, the animal burrows into the bottom mud. As the mud dries, the siren’s skin glands produce a thick mucus layer that becomes a parchmentlike cocoon that prevents the salamander from drying out. It can aestivate this way for several months, until rains again fill the pond.

Forages at night for small crayfish, aquatic insects, snails, and worms. This species can apparently obtain food by filter feeding through bottom material and in aquatic vegetation, gleaning small crustaceans such as water fleas, aquatic pill bugs, scuds, seed shrimp, and so on.

Life Cycle

Little is known of the courtship and mating of this species. In spring, typically in March and April, the female lays from 100 to over 350 eggs in small pockets in the bottom mud of a pond or ditch or in aquatic vegetation. The male fertilizes the eggs by spraying sperm on the eggs within the nesting area. The male protects the nest by biting other sirens that get too close. He also provides paternal care to the eggs by constantly fanning them with his tail, which increasing the aeration, and by keeping the nest cleaned. The eggs hatch in 6 to 10 weeks. It takes two years for a western lesser siren to reach maturity.

If you are fishing and catch a lesser siren (or any other amphibian), cut the line and release it unharmed. Most amphibian populations are declining, none are venomous, and none threaten our fisheries. They are an integral part of our aquatic fauna. Western lesser sirens are completely harmless to humans.

The name siren originates with Greek mythology, where sirens are characters that ensnare people with their beautiful songs. There are many stories about them in Classical literature, and in some cases they are aquatic, similar to mermaids. As it turns out, the western lesser siren is known to produce two kinds of sounds, which they apparently use for communication. When captured, sirens produce a yelp; when another siren approaches, a siren makes clicking sounds, often accompanied with head movements, apparently as a form of territorial defense.

The western mudsnake of southeastern Missouri specializes in eating our two eel-like amphibians, the amphiuma and the lesser siren. The slippery amphibians thrash wildly, but the snake pokes its prey with its pointy tail tip. This makes the amphibian uncurl and easier to swallow.

Other animals that prey on western lesser sirens include minks and great egrets.

This species is one of four members of the siren family; all are restricted to North America. Sirens have external gills, an eel-like body, and only forelimbs. There are various subspecies. The closest relative to our siren is the greater siren (Siren lacertina), which is one of the longest salamanders in the United States, reaching more than 3 feet in length. It occurs in America's southeast coastal plains. The other two sirens are called dwarf sirens (genus Pseudobranchus); both are small, slender salamanders the live in the extreme southeastern United States.

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Similar Species
About Reptiles and Amphibians in Missouri
Missouri’s herptiles comprise 43 amphibians and 75 reptiles. Amphibians, including salamanders, toads, and frogs, are vertebrate animals that spend at least part of their life cycle in water. They usually have moist skin, lack scales or claws, and are ectothermal (cold-blooded), so they do not produce their own body heat the way birds and mammals do. Reptiles, including turtles, lizards, and snakes, are also vertebrates, and most are ectothermal, but unlike amphibians, reptiles have dry skin with scales, the ones with legs have claws, and they do not have to live part of their lives in water.