Sirens are a unique group of permanently aquatic salamanders. Sirens are neotenic or paedomorphic animals, meaning that they retain their juvenile characteristics into adulthood. A baby salamander, or larva, typically hatches with a set of external gills for breathing water and front legs develop shortly afterward if they aren’t already present – with back legs coming in some time later. As the salamander grows, it usually develops eyelids, thicker skin for living outside of water, and it will absorb its gills and move at least partially onto land. Sirens, however, stop the metamorphosis process after developing the front arms – they never grow hind legs, never lose their gills, and never leave the water.
This creates a problem for the siren – what do they do if their pond dries up? Ephemeral (temporary) wetlands are some of the best places for amphibians to live, since the fish that would eat adults, larvae, or eggs can’t survive without water. Most frogs and salamanders can simply leave the wetland and will do fine if they can stay moist, but sirens can’t survive in the surrounding forest. Instead, sirens aestivate, which is similar to hibernation. When a wetland dries up, sirens burrow deep into the mud and secrete mucus through their skin that hardens into a water-tight cocoon around them. In this state, the siren can survive for months until the water returns. Scientists have done studies on a larger species, the greater siren, and have found that they can survive for over a year and a half like this, living off of energy stored in their body as fat.
One neat thing about sirens is that they’re extremely good at surviving. In addition to their aestivating abilities, sirens are able to breathe in three different ways – through their gills, through their skin (all amphibians can breathe partially through their skin, some more than others), and through lungs. Sirens often times live in water with very poor quality and limited dissolved oxygen for fish to survive – this acts as extra protection from many kinds of predators. Sirens are also extremely slippery, helping them to escape being eaten. In the wild, wading birds like herons, large fish, and snakes are some of the more common predators – mud and rainbow snakes are two species of snakes that almost exclusively eat sirens or another aquatic salamander called an amphiuma. In turn, sirens will eat dead fish, tadpoles, and aquatic insects.
Sirens are found almost exclusively in the south-eastern United States living in wetter areas, though the western lesser siren can be found as far west as Texas and north into Michigan and Illinois. In South Carolina, sirens can be found throughout the sandhills and coastal plains regions. South Carolina has three species of siren – the eastern lesser siren (Siren intermedia intermedia), the greater siren (Siren lacertina) and the state threatened northern dwarf siren, (Pseudobranchus striatus). The two sirens on display at the center were captive bred animals, with the parents collected near Columbia, SC – they mainly eat worms, pieces of shrimp, and artificial crab meat.
Our two sirens are Aglaope (agh-lah-OH-pee) and Peisinoe (pee-see-NOH-ee), named after two of the sirens from Greek myth. Money from ADOPT donations will mostly go toward buying worms to feed them, a new filter, or for additional plants.