The Sirens are a family of aquatic salamanders. The have small front extremities and lack hind ones. In contrast to most other salamanders they have external gills not only in larvae state, but also in adulthood. The Sirens are limited to North America.
Sirens are quite distinct from other salamanders, hence they form their own suborder Sirenoidea of the Caudata order. Sometimes they are even referred as a completely distinct order Meantes or Trachystomata. Genetic analysis also confirms that the Sirens are not closely related to any other Salamander groups.
The Siren family (Sirenidae) is subdivided into two genera, with two species each: