» Not to be confused with order Sirenia (manatees and dugongs) The Sirenidae, or 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 forelimbs's made of only cartilage. Sirens are found only in the south-eastern United States, and northern Mexico. If the conditions of a water source are unsuitable, a larva will shrink its gills to mere stumps, and may not function at all. They're also able… (More on Sirenidae)