Sirenidae | |
---|---|
Siren intermedia | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Amphibia |
Order: | Urodela |
Family: | Sirenidae Gray, 1825 |
Genera | |
Sirenidae, the sirens, are a family of neotenic aquatic salamanders. Family members have very small fore limbs and lack hind limbs altogether. [1] In one species, the skeleton in their fore limbs is made of only cartilage. In contrast to most other salamanders, they have external gills bunched together on the neck in both larval and adult states. Sirens are found only in the Southeastern United States and northern Mexico. [1]
Although they are primarily carnivorous, they are the only salamanders observed eating plant material. [2]
Sirens are quite distinct from other salamanders, and in some classifications they form their own suborder, Sirenoidea, or as a completely distinct order (Meantes or Trachystomata). Genetic analysis variously places them as the sister to other Salamandroidea [3] [4] or as sister to all other salamanders. [5] Many of their unique characteristics seem to be partly primitive and partly derivative.
Sirens are generally eel-like in form, with two tiny, but otherwise fully developed, fore limbs. They range from 25–95 cm (9.8–37.4 in) in length. [1] They are neotenic, although the larval gills are small and functionless at first, and only adults have fully developed (but inefficient) gills. They are obligate air-breathers with well developed lungs. [6] Proving they likely evolved from a terrestrial ancestor with an aquatic larval stage. Like amphiumas, they are able to cross land on rainy nights.
These amphibians are omnivorous, feeding mainly on worms, small snails, shrimps, and filamentous algae. [7] They are notable among salamanders (and most amphibians, aside from a few frog species) due to their semi-herbivorous habits. [2] Their jaws possess sharp-edged keratinised and toothless ridges, like many anuran tadpoles, but the coronoid bone in the lower jaw and the vomer and palatine bone in the upper jaw have patches of monocuspid and unbladed teeth arranged in polystichous patterns. [8]
If the conditions of a water source are unsuitable, a larva will shrink its gills to mere stumps, and these may not function at all. [7] They are also able to burrow into mud of drying ponds and encase themselves with a cocoon of mucus to survive periods of drought. [1] During such periods, they breathe with their small but functional lungs.[ citation needed ]
Unlike other salamanders, an interventricular septum is present in the heart. At least two of the species can produce vocalizations.
The structure of sirens' reproductive systems suggests they employ external fertilization. [1] This has finally been confirmed in captive breeding experiments, showcasing that males also engage in parental care, building nests for their offspring. [9] Parental care among sirens is paternal due to external fertilization. In S. intermedia males circle around females and may rub or bite her flank region. [9] Both male and female will go on their backs and turn. It is assumed here where the female spawns and the male fertilizes her eggs. [9] After the courtship is over, the female leaves and the male guards the eggs. Males could potentially guard more than one brood, but they are known to bite females who enter a nesting site. [9] Paternal care has also been observed in Cryptobranchoidea, the other suborder with external fertilization. [9] This is critical to phylogeny, as Salamandroidea, the third suborder, use internal fertilization which may be pair with maternal care, meaning that sirens are one of the oldest groups of salamanders. [9]
The combined biomass of Siren intermedia species in a Texas pond exceeded the total biomass of the pond's seven species of fish. [10]
The siren family (Sirenidae) is subdivided into five genera, three extinct, and two extant with two and three extant species, respectively:
Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods, excluding the amniotes. All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura (frogs), Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater, wetland or terrestrial ecosystems. Their life cycle typically starts out as aquatic larvae with gills known as tadpoles, but some species have developed behavioural adaptations to bypass this.
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten extant salamander families are grouped together under the order Urodela from the group Caudata. Urodela is a scientific Latin term based on the Ancient Greek οὐρά δήλη: ourà dēlē "conspicuous tail". Caudata is the Latin for "tailed ones", from cauda : "tail".
The axolotl is a paedomorphic salamander closely related to the tiger salamander. It is unusual among amphibians in that it reaches adulthood without undergoing metamorphosis. Instead of taking to the land, adults remain aquatic and gilled. The species was originally found in several lakes underlying what is now Mexico City, such as Lake Xochimilco and Lake Chalco. These lakes were drained by Spanish settlers after the conquest of the Aztec Empire, leading to the destruction of much of the axolotl's natural habitat.
The mole salamanders are a group of advanced salamanders endemic to North America. The group has become famous due to the presence of the axolotl, widely used in research due to its paedomorphosis, and the tiger salamander which is the official amphibian of many US states, and often sold as a pet.
The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include some of the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two living families—the other being the Asiatic salamanders belonging to the family Hynobiidae—within the Cryptobranchoidea, one of two main divisions of living salamanders.
Plethodontidae, or lungless salamanders, are a family of salamanders. With over 500 species, lungless salamanders are by far the largest family of salamanders in terms of their diversity. Most species are native to the Western Hemisphere, from British Columbia to Brazil. Only two extant genera occur in the Eastern Hemisphere: Speleomantes and Karsenia.
Ambystomatidae is a family of salamanders belonging to the Suborder Salamandroidea in the class Amphibia. It contains two genera, Ambystoma and Dicamptodon. Ambystoma contains 32 species and are distributed widely across North America, while Dicamptodon contains four species restricted to the Pacific Northwest. These salamanders are mostly terrestrial and eat invertebrates, although some species are known to eat smaller salamanders. They can be found throughout the US and some areas of Canada in damp forests or plains. This family contains some of the largest terrestrial salamanders in the world, the tiger salamander and the coastal giant salamander. Some species are toxic and can secrete poison from their bodies as protection against predators or infraspecific competition. Neoteny has been observed in several species in Ambystomatidae, and some of them like the axolotl live all of their lives under water in their larval stage.
The family Proteidae is a group of aquatic salamanders found today in the Balkan Peninsula and North America. The range of the genus Necturus runs from southern central Canada, through the midwestern United States, east to North Carolina and south to Georgia and Mississippi. The range of the olm, the only extant member of the genus Proteus, is limited to the Western Balkans. The fossil record of the family extends into the end of the Late Cretaceous, with Paranecturus being known from the Maastrichtian of North America.
The two-toed amphiuma is an aquatic salamander widely distributed in the southeastern United States. It is commonly, but incorrectly, called "congo snake", "conger eel" or the "blind eel".
Dissorophoidea is a clade of medium-sized, temnospondyl amphibians that appeared during the Moscovian in Euramerica, and continued through to the Late Permian and the Early Triassic of Gondwana. They are distinguished by various details of the skull, and many species seem to have been well adapted for life on land.
Taylor's salamander is a species of salamander found only in Laguna Alchichica, a high-altitude crater lake to the southwest of Perote, Mexico. It was first described in 1982 but had been known to science prior to that. It is a neotenic salamander, breeding while still in the larval state and not undergoing metamorphosis. The lake in which it lives is becoming increasingly saline and less suitable for the salamander, which is declining in numbers. The International Union for Conservation of Nature (IUCN) has rated it as being "critically endangered".
Anderson's salamander is a neotenic salamander from Zacapu Lagoon in the Mexican state of Michoacán.
The blunt-headed salamander is a mole salamander endemic to Mexico. It is only known from the vicinity of its type locality, near Morelia, in Michoacán state in Southwestern Mexico. It inhabits a landscape consisting of a mosaic of natural grasslands and pine-oak forests at elevations of about 2,000 m (6,600 ft) asl. Breeding takes place in ponds. An average adult has a mass of 6.18 grams while wet. Adult females of the species range from 42-93 mm and males range from 45.4-70.5 mm in standard length.
Siren is a genus of aquatic salamanders of the family Sirenidae. The genus consists of five living species, along with one extinct species from the Eocene Epoch and three from the Miocene.
The lesser siren is a species of aquatic salamander native to the eastern United States and northern Mexico. They are referred to by numerous common names, including two-legged eel, dwarf siren, and mud eel. The specific epithet intermedia denotes their intermediate size, between the greater siren, Siren lacertina, and the dwarf sirens, Pseudobranchus species.
External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside the pharynx and covered by gill slits, as they are in most fishes. Instead, the respiratory organs are set on a frill of stalks protruding from the sides of an animal's head.
The Cryptobranchoidea are a suborder of salamanders found in Asia, European Russia, and the United States. They are known as primitive salamanders, in contrast to Salamandroidea, the advanced salamanders. It has two living subdivisions, Cryptobranchidae, and Hynobiidae, commonly known as Asian salamanders.
The ocoee salamander is a species of salamander in the family Plethodontidae. This salamander has a variety of colors and patterns, and got its name from Tennessee state wildflower. Its natural habitats are temperate forests, rivers, intermittent rivers, freshwater springs and wet rocks in mountainous areas of the Southeastern United States. It was first described by Nicholls in 1949. They are territorial and feed on small invertebrates. It is widely distributed in the southeastern United States and is listed as "Least Concern" by the International Union for Conservation of Nature.
Uranocentrodon is an extinct genus of temnospondyls in the family Rhinesuchidae. Known from a 50 centimetres (20 in) skull, Uranocentrodon was a large predator with a length up to 3.75 metres (12.3 ft). Originally named Myriodon by van Hoepen in 1911, it was transferred to a new genus on account of the name being preoccupied in 1917. It has been synonymized with Rhinesuchus, but this has not been widely supported. It was also originally considered to be of Triassic age, but more recent analysis has placed its age as just below the Permian-Triassic boundary.
The reticulated siren, also known as the leopard siren or colloquially as the leopard eel, is a species of aquatic salamander in the family Sirenidae. The species, which is endemic to the southeastern United States, was first formally described in 2018. This cryptic salamander is known only from three localities in southern Alabama and the Florida panhandle and is one of the largest animals in the United States to be newly described in the past 100 years.
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