In contrast to most other salamanders, they have external gills bunched together on the neck in both larval and adult states.

Sirens are generally eel-like in form, with two tiny, but otherwise fully developed, fore limbs.

These amphibians are omnivorous, feeding mainly on worms, small snails, shrimps, and filamentous algae.

[8] If the conditions of a water source are unsuitable, a larva will shrink its gills to mere stumps, and these may not function at all.

[7] They are also able to burrow into mud of drying ponds and encase themselves with a cocoon of mucus to survive periods of drought.

[1] This has finally been confirmed in captive breeding experiments, showcasing that males also engage in parental care, building nests for their offspring.

[9] This is critical to phylogeny, as Salamandroidea, the third suborder, use internal fertilization which may be pair with maternal care, meaning that sirens are one of the oldest groups of salamanders.