I’m currently working on a book titled A Lotl About Axolotls, an amphibian who never fully matures into an adult salamander with lungs. They keep their juvenile features, complete with frilly exterior gills—a very interesting adaptation to their environment.
Recently, I learned about an equally unusual salamander found in the Rio Grande River: the Rio Grande Siren or lesser siren (Siren intermedia). Its range includes southern Texas and northern Mexico. I didn’t know the US had its own paedomorphosic amphibian! Thrilling!
An Eel-Like Amphibian
The siren is another aquatic salamander. Its species name, intermedia, means intermediate because they are smaller than the greater siren (Siren lacertina) but bigger than the dwarf sirens (Pseudobranchus species).
These sirens have the expected elongated body, which is described as eel-like. They possess only two limbs, emerging just behind the head, complete with legs that have four toes. Like the axolotl, sirens retain their external gills.
Interestingly, unlike many other salamanders, male sirens are typically larger than females, and they often sport a particularly large head. They can be olive green, blue-gray, or black, sometimes featuring spots.
Masters of the Swamp
Sirens spend their entire lives in swamps and ponds, rarely leaving the water. Their distribution is limited because of this, as their short legs are not of much use on land.
In their aquatic environment, sirens are bottom dwellers, sifting through the muck for small fish, insects, and crustaceans.
Their most remarkable survival strategy is their ability to aestivate (a state similar to hibernation) for up to two years in dry ponds. To retain water and electrolytes during this dry period, they create a protective mucoid cocoon. This ability to wait out severe drought is quite remarkable.
The Rio Grande Siren is considered one of North America’s most elusive amphibians, thanks to its secretive nature and specific habitat requirements. I didn’t realize there were so many interesting salamanders right here!
Discover More Unique Amphibian Adaptations!
Are you fascinated by amazing creatures like the Axolotl and the Rio Grande Siren? You can find fun and educational content, including workbooks, based on unique regional animals, like those in the Southern Arizona and The Bahamas!