Sirenidae

 ( Cenomanian First Appearances ) 

Although they are primarily carnivore, they are the only salamanders observed eating plant material.Hill, R. L., Mendelson, J. R. & Stabile, J. L. 2015. Direct observation and review of herbivory in Sirenidae (Amphibia: Caudata). Southeastern Naturalist 14, N5-N9.

Sirens are generally eel-like in form, with two tiny, but otherwise fully developed, fore limbs. They range from in length. They are Neoteny, although the larval are small and functionless at first, and only adults have fully developed (but inefficient) gills. They are obligate air-breathers with well developed lungs. Proving they likely evolved from a terrestrial ancestor with an aquatic larval stage. Like , they are able to cross land on rainy nights.

These amphibians are omnivorous, feeding mainly on , small , , and filamentous algae.John Farrand Jr., The Audubon Society Encyclopedia of Animal Life, 1982 They are notable among salamanders (and most amphibians, aside from a few frog species) due to their semi-herbivorous habits. Their jaws possess sharp-edged keratinised and toothless ridges, like many anuran tadpoles, but the coronoid bone in the lower jaw and the vomer and palatine bone in the upper jaw have patches of monocuspid and unbladed teeth arranged in patterns.

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. They are also able to burrow into mud of drying and encase themselves with a cocoon of mucus to survive periods of drought. During such periods, they breathe with their small but functional .

Unlike other salamanders, an interventricular septum is present in the heart. At least two of the species can produce vocalizations.

The structure of sirens' reproductive systems suggests they employ external fertilization. This has finally been confirmed in captive breeding experiments, showcasing that males also engage in parental care, building nests for their offspring.Reinhard, S., Voitel, S. & Kupfer, A. 2013. External fertilisation and paternal care in the paedomorphic salamander Siren intermedia Barnes, 1826 (Urodela: Sirenidae). Zoologischer Anzeiger 253, 1–5. Parental care among sirens is paternal due to external fertilization. In S. intermedia males circle around females and may rub or bite her flank region. Both male and female will go on their backs and turn. It is assumed here where the female spawns and the male fertilizes her eggs. After the courtship is over, the female leaves and the male guards the eggs. Males could potentially guard more than one brood, but they are known to bite females who enter a nesting site. Paternal care has also been observed in Cryptobranchoidea, the other suborder with external fertilization. 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.

The combined biomass of Lesser Siren species in a Texas pond exceeded the total biomass of the pond's seven species of fish.

• Genus † Habrosaurus Gilmore 1928
• † H. dilatus Gilmore 1928
• † H. prodilatus Gardner 2003
• Genus † Kababisha Evans et al. 1996
• † K. humarensis Evans et al. 1996
• † K. sudanensis Evans et al. 1996
• Genus † Noterpeton Rage et al. 1993
• † Noterpeton bolivianum Rage et al. 1993
• Genus Pseudobranchus Gray 1825
• † P. robustus Goin and Auffenberg 1955
• † P. vetustus
• P. axanthus Netting & Goin 1942 southern dwarf siren
• P. striatus LeConte 1824 northern dwarf siren
• Genus Siren Österdam 1766 sirens
• † Siren dunni Goin and Auffenberg 1957
• † Siren hesterna
• † Siren miotexana
• † Siren simpsoni
• Siren intermedia Barnes 1826 lesser siren
• Siren lacertina Carl Linnaeus, 1766 greater siren
• S. nettingi Goin, 1942 western siren
• Siren reticulata Graham, Kline, Steen & Kelehear, 2018 reticulated siren
• S. sphagnicola Fedler, Enge, & Moler, 2023 seepage siren

• Tree of Life: Sirenidae