Sirenoidea
| Sirenidae Temporal range: Late Cretaceous - Present, 95–0 Ma |
|
|---|---|
 |
|
| Siren intermedia | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Urodela |
| Suborder: | Salamandroidea |
| Family: |
Sirenidae Gray, 1825 |
| Genera | |
†Habrosaurus
Pseudobranchus
Siren
Sirenidae, the sirens, are a family of aquatic salamanders. Family members have very small fore limbs, and lack hind limbs altogether. 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.
Although they are primarily carnivorous, they are the only salamanders observed eating plant material.
Sirens are quite distinct from other salamanders, hence they form their own suborder, Sirenoidea. Sometimes, they are even referred to as a completely distinct order (Meantes or Trachystomata). Genetic analysis confirms the sirens are not closely related to any other salamander group. 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. They are neotenic, although the larval gills are small and functionless at first, and only adults have fully developed gills. Because of this, sirens most likely have evolved from a terrestrial ancestor that still had an aquatic larval stage. Like amphiumas, they are able to cross land on rainy nights.
Except for some patches of small teeth on their palates and on the splenial bone on the inner side of their lower jaws, their mouths have lost all dentition and have been replaced with a horny sheath that resembles a beak. Sirens are omnivorous, feeding mainly on worms, small snails, shrimps, and filamentous algae. They are notable among salamanders (and most amphibians, aside from a few frog species) due to their semi-herbivorous habits.
...
Wikipedia