Sirenidae
| Sirenidae | |
|---|---|
 | |
| Siren intermedia | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Urodela |
| Family: | Sirenidae Gray, 1825 |
| Genera | |
Sirenidae, the sirens, are a family of neotenic aquatic salamanders. Family members have very small fore limbs, and lack hind limbs altogether.[1] In one species, the skeleton in their fore limbs is made of only cartilage. In contrast to most other salamanders, they have external gills bunched together on the neck in both larval and adult states. Sirens are found only in the Southeastern United States and northern Mexico.[1]
Although they are primarily carnivorous, they are the only salamanders observed eating plant material.[2]
Description
[edit]Sirens are quite distinct from other salamanders, and in some classifications they form their own suborder, Sirenoidea, or as a completely distinct order (Meantes or Trachystomata). Genetic analysis variously places them as the sister to other Salamandroidea[3][4] or as sister to all other salamanders.[5] Many of their unique characteristics seem to be partly primitive and partly derivative.
Sirens are generally eel-like in form, with two tiny, but otherwise fully developed, fore limbs. They range from 25–95 cm (9.8–37.4 in) in length.[1] They are neotenic, although the larval gills are small and functionless at first, and only adults have fully developed (but inefficient) gills. They are obligate air-breathers with well developed lungs,[6] proving they likely evolved from a terrestrial ancestor with an aquatic larval stage. Like amphiumas, they are able to cross land on rainy nights.
These amphibians are omnivorous, feeding mainly on worms, small snails, shrimps, and filamentous algae.[7] They are notable among salamanders (and most amphibians, aside from a few frog species) due to their semi-herbivorous habits.[2] 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