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Siren
Photo © 2006 Jim Jung.
All rights reserved.

Sirens

Siren intermedia

It's been my experience that if you tell someone your favorite amphibian is a Siren (Siren intermedia nettingi) you're met with blank looks. Which is hardly surprising since these are obscure (but often abundant) little beasts - seldom mentioned and almost never seen - and these are my favorite amphibians of all time.

Classification

Sirens are classified as salamanders principally because taxonomists dislike creating new orders to house just one or a few species and such reclassification requires rewriting all the textbooks. But Sirens have enough oddities and peculiarities to cause even staunch taxonomical "lumpers" to think twice concerning this animal's current classification with the salamanders.

Sirens are probably the most ancient line of salamanders now alive on planet earth. Obviously related creatures very similar to them were wriggling through the roots of the coal swamps here a quarter of a billion years ago, and they're still here today when the swamps and everything in them have long since turned to stone.

Siren showing most of its length, Siren intermedia nettingi
Photo © 2006 Jim Jung. All rights reserved.

Description

Sirens are large, eel-like creatures that can reach 16 inches in length and an inch in diameter. They have a pair of small front legs which they use to pull themselves through their weedy, murky world - and no hind legs - and unlike any other salamander each of their four toes ends in a claw or toenail which on a salamander is a very odd thing indeed. They posses lungs as well as large, feathery gills and in addition can breathe through their extremely slippery skins; so they've covered all their respiratory bases. Adults have small, horny "beaks" in their mouths instead of teeth. Their actual teeth are located in their throats so Sirens don't bite; they aren't poisonous; and are therefore understandably shy since everything larger than they are finds them very tasty morsels indeed.

Habitat

Sirens are permanently aquatic and live in shallow, weed-filled aquatic habitats like ditches, sloughs, swamps and temporary pools devoid of fish. When their pool dries up they burrow into the soft mud bottom and form a sort of cocoon made of old skin and hardened slime. Here they sleep away the dry months - large adults are capable of surviving this way for nearly two years - waiting patiently for the rains to return. When their pool refills the Sirens wriggle free of their old cocoon and begin their aquatic life anew.

Feeding

Sirens are generalists when it comes to feeding and can survive on a large size-range of food ranging from microscopic organisms which they filter feed to large creatures like small fish, dragonfly larvae and crayfish. They'll readily devour mosquito larvae, tadpoles, snails, bryozoans, paramecium and anything else they can wrestle down their throats. Their favorite food (at least in our area) appears to be small crayfish which they eat in a most unique way.

I presented a captive Siren with a small crayfish once. The crayfish sat on the bottom of the tank waving its antennae and tasting the water in its new home. A large Siren, its curiosity piqued, came cruising up to the crayfish and stopped just short of it, sniffing the water. It then very slowly raised its head above the crayfish and gently brought it down on its back as if it were kissing it.

In the blink of an eye the Siren sucked the crayfish into its mouth - sort of folding the unfortunate crayfish in half since only its tail and head and pincers were visible. The Siren worked the crayfish around in its mouth thoughtfully for a moment and then spit it back out so that the crayfish settled gently back onto the floor of the tank.

I thought the experiment in Siren feeding had failed since the Siren had apparently failed to eat the creature. Then I noticed that the crayfish was no longer moving. Looking very closely I noticed that the crayfish had a slit up its back where the Siren had folded it. Looking even more closely I discovered that I was looking at an empty shell. The Siren had sucked the crayfish right out of its carapace and left the inedible shell behind!

Sound and sirens

Sirens also use sound to communicate with each other. During the day when not actively feeding they stay holed up in small burrows which they leave occasionally to rise to the surface for a gulp of air. Just before leaving the burrow they emit a series of faint clicking noises which are often answered by neighboring Sirens. In addition they emit a loud yelp when caught by a predator or attacked by other Sirens. ( These inter-Siren attacks are designed to establish territorial boundaries rather than as food procurement. Sirens aren't cannibalistic.)

Stubbornly neotonic

Sirens are also unique in that unlike all other aquatic salamanders they cannot be induced to transform into land living forms with drugs. Mud Puppies, Amphiumas, Axolotls, and Hellbenders are all permanently aquatic and never transform into land living adults like the Mole Salamander clan. But if some meddlesome human should inject any of these species with certain hormones they do transform resulting in a very confused and unhappy terrestrial salamander. Sirens remain serene and unaffected.

Young Siren briefly removed from water
Photo © 2004 Mike Pingleton. All rights reserved.

Reproduction

Sirens, like most salamanders in our area, don't hibernate since they're active as long as their ponds remain full, even when covered with ice. With the rapidly lengthening and warming days of early March they become more active. Tender sentiment and romantic longings arise in their neotenic breasts and males begin cruising for receptive females. When a male encounters his true love his first act is to bite her - usually in the area of the cloaca. At this time of year every mature female exhibits bite marks and scars.

Mating behavior has never been observed in this species but it obviously occurs. Based on the few facts we have, it seems to involve external fertilization - another unique trait reserved almost exclusively to this creature. Females apparently wait for passing males in a depression they construct on the bottom of their pond.

Once the eggs are laid - up to a hundred or more for large females - the female coils about them and guards the eggs against all comers. While Sirens will not eat others of their own kind - even hatchlings - they have an entirely different attitude concerning Siren eggs which would be greedily gobbled up were they not guarded. The female probably remains with the eggs until they hatch - usually within two weeks of laying - and then returns to her burrow to heal up from her ordeal of lovemaking and fatten up in preparation for another bout the following spring.

Siren showing feet and gills, Siren intermedia nettingi
Photo © 2006 Jim Jung.
All rights reserved.

General remarks

Sirens are extremely interesting amphibians - and no little part of that interest involves all the mysteries this species still guards. As inhabitants of their habitats they're extremely successful and Siren numbers are correspondingly high. Should you find a pool with one you can bet that there are dozens - or hundreds more - hiding in the weeds and muck out of sight.

Sirens can be found (with difficulty) in almost any floodplain pond, slough or ditch in our area. When not actively searching for one, I have only seen a siren in its natural habitat once - and that was in Louisiana, the stronghold of this species - so the odds of you catching a glimpse of these animals in the wild are almost nil. But knowing that they're out there patrolling their ponds, gossiping with their neighbors and sleeping the summer away in dried up ditches and pools should give any amphibian lover a warm glow whenever suitable habitat flashes by the car window.

Sirens are utterly, totally, supremely ... cool.



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The information on this page is tailored to Southern Illinois, Southwest Indiana, Western Kentucky, and Southeast Missouri

Copyright © 2004 Jim Jung