Siren

Family Sirenidae

Amphibian

Transcript:

Today on Animal Fact Files we’re discussing sirens. These salamanders are eel shaped and have external gills like an axolotl or water dog. Though sirens, axolotls, and water dogs have a similar appearance, they aren't classified in the same family. There are currently five described living members of the siren family and these are further split into the sirens and the dwarf sirens. They can be told apart by their toes! We'll be discussing all five species in today's episode and using the common name "siren" to describe the family as a whole.

Sirens live from the southeastern United States to northern Mexico. Unlike some salamanders who require clean, moving waters, sirens actually prefer murky, stagnant water with lots of dense vegetation. Sirens live in swamps, slow moving streams, ditches, and even ephemeral ponds that dry up during part of the year. When their home goes dry, a siren will burrow into the mud at the bottom and build a cocoon for itself out of its own skin! They'll enter a low energy state kind of like hibernation until the water returns. During this time they won't eat, instead surviving on fat stored in their body. They can lose up to 80% of their body mass and survive for years while in this state. Their gills shrivel during this time, as well. Sirens can breathe through their skin, their lungs, and their gills, so their gills aren't always necessary to live.

Like an axolotl, a siren's external gills are a holdover from their juvenile stage. They retain these juvenile characteristics into adulthood! This is known as neoteny. Unlike many other salamanders who become terrestrial in adulthood, sirens remain aquatic throughout their entire life. This works out because they don't even have back legs. Sirens have front legs, but no back legs. Their front legs are used to crawl along the bottom of the water column, but these amphibians also swim by undulating their body and tail like a fish!

Sirens range from four inches to over three feet (10-91cm) in length. Their tail makes up anywhere from 25-40% of their length. Males and females can not be told apart just by looking at them. These salamanders spend the day hiding in vegetation. At night, they come out to hunt fish, insects, worms, mollusks, and more. Sirens catch prey by sucking it in. Because of this, it's debated if sirens are omnivores. Technically, they've been found with algae in their stomachs, but it's unknown if this was purposefully collected or just a byproduct of their suction method of feeding. Threats to sirens include mud snakes, wading birds, and alligators.

It's unknown how long these amphibians live, though one zoo has claimed a captive individual reached 25 years of age. There's also very little known about their breeding. They travel to shallow water to breed. It's believed sirens have external fertilization and a female can lay anywhere from under 100 to over 1,000 eggs. These are adhesive and may be laid singly in vegetation or in groups like little clusters of grapes. The eggs are guarded by either of the parents - studies have suggested both, though most describe the female as the protector. The eggs hatch a few months later and it can take less than a year to a few years for them to reach reproductive maturity. As they get older and bigger they move to deeper water.

Though they will bite if threatened, sirens aren't venomous. Their secretions are also harmless so they aren't poisonous either. When disturbed, they may yelp or scream like a young rabbit to indicate their distress: (audio). This is why they get their common name!

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