Everything about Sirenidae totally explained
» Not to be confused with order Sirenia (manatees and dugongs)sirens are a
family of
aquatic salamanders. Family members have small front extremities and lack hind
limbs. In one species, the
skeleton in their forelimbs is made of only
cartilage. Sirens are limited to the
North American continent. In contrast to most other salamanders they've external
gills bunched together on the
neck in both
larval and adult states.
Description
Sirens are quite distinct from other caudates, hence they form their own suborder
Sirenoidea. Sometimes they're even referred as a completely distinct order (
Meantes or
Trachystomata). Genetic analysis confirms that sirens are not closely related to any other salamander group. Many of their unique characteristics seem to be partly
primitive and partly
derivative.
They are not primitive as one may think, but
degenerated. The larval gills are small and functionless at first, and only adults have fully-developed gills in form and function. Because of this, it's most likely sirens have evolved from a
terrestrial ancestor that still had an aquatic larval stage. Like
amphiumas (congo eels), they're probably able to cross land on moist nights through wet grass.
Except for some patches of small
teeth on their
palate and on the
splenial bone on the inner side of their lower
jaw, their
mouth has lost all dentition and has been replaced with a horny sheath that resembles a
beak. Sirens
feed mainly on
worms, small
snails,
shrimps, and
filamentous algae.
If the conditions of a water source are unsuitable, a larvae will shrink its gills to mere stumps, and may not function at all. They are also able to
burrow into
mud of drying
ponds and become
entombed, covering themselves with a
cocoon. In this period they
breathe with small but functional lungs.
Unlike other salamanders, an inter
ventricular septum is present in the
heart. At least two of the species can produce
vocalizations. Like the suborder
Cryptobranchoidea, siren members are most likely external fertilizers.
The combined
biomass of
Siren intermedia species in a
Texas pond exceeded the total biomass of the pond's seven species of
fish.
Taxonomy
The siren family (Sirenidae) is subdivided into two genera, with two species each:
Further Information
Get more info on 'Sirenidae'.
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