On occasion a Siren might take a fisherman's baited hook, but this would be an uncommon and minor annoyance. These animals are properly considered harmless to human interests.
Siren intermedia is an eel-like salamander with a long slender body (18-68 cm long) and a very small dorsal fin that runs from the vent to the tail tip. It has only a pair of front legs; each foot has four toes. The front legs are very reduced and the rear legs are completely absent. The head is rather flattened, and there are bushy external gills located on each side of the head. Siren intermedia varies in coloration from light grayish green to olive or black; there are also small irregular markings (dots) that are visible on lighter colored individuals.
Larvae and juveniles are more brightly marked, with a red band across the nose and along the side of the head.
Other Physical Features: endothermic ; ectothermic ; heterothermic ; bilateral symmetry
Average lifespan
Status: captivity: 6.3 years.
Siren intermedia will inhabit most any slow and sluggish body of water that is shallow and with plenty of aquatic vegetation, including marshes, ponds, ditches, and canals. In most circumstances they need a permanent or semi-permanent body of water but they are able to move short distances over land if factors are right or stay encased in a cocoon of slime if drought occurs.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: lakes and ponds
Wetlands: marsh ; swamp ; bog
Siren intermedia, the Lesser Siren, ranges from the Coastal Plains of Virginia to Florida, then westward to southern Texas and northeastern Mexico. Populations extend northward in the Mississippi Valley to Illinois, Indiana, and southwestern Michigan. Geographic isolates occur in northern Indiana, southwest Michigan, northeastern North Carolina, and southeastern Virginia.(Petranka 1998) This range is occupied by three subspecies, they are S. i. intermedia, S. i. nettingi, and S. i. texana. All of these subspecies only vary slightly in physical characteristics such as length and color (Conant and Collins, 1998).
Biogeographic Regions: nearctic (Native )
Siren intermedia feeds primarily on aquatic invertebrates such as crustaceans, insect larvae, worms, and snails. They will also readily consume young amphibian larvae and their own eggs. Siren intermedia often feeds by gulping large quantities of material at a time, which is filtered through the bronchial openings. Vegetable matter sometimes found in their digestive tracts is probably eaten accidentally.
Animal Foods: insects; terrestrial non-insect arthropods; mollusks; terrestrial worms; aquatic crustaceans
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods, Molluscivore , Vermivore)
Sirens are occasionally used for fish bait, but this species normally attracts little attention from humans. They occupy a predatory niche in shallow freshwater habitats, and have ecological value in the environment.
Development - Life Cycle: metamorphosis
Siren intermedia is extremely rare and possibly extirpated in Michigan but this species is not threatened over most of its range. It could be harmed by chemicals such as Rotenone, which is used as a fisheries management tool and can be fatal to aquatic amphibians such as Siren intermedia. Another factor that may affect the vitality of this species is habitat destruction and the filling in of wetlands.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
The courtship behavior of Siren intermedia has not yet been described. Fertilization has been presumed to be external, since the females lack cloacal sperm storage areas. There is thought to be a lot of aggression during mating due to the amount of scaring from bite marks on both the males and females. Eggs are laid in early spring they are deposited in shallow depressions in the soft bottom of the occupied water body, usually in highly vegetated areas. In these shallow depressions the female will lay from 12 to over 300 eggs; the female may lay multiple clutches through out the season. Freshly laid eggs are dark brown and 2.5-3 mm in diameter. The hatchling larvae are about 1.1 cm in length. (Petranka 1998; Harding 1997)
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate)
Average number of offspring: 200.
Average age at sexual or reproductive maturity (male)
Sex: male: 730 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 730 days.
The lesser siren (Siren intermedia) 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.
Lesser sirens have elongated bodies possessing only two limbs, a pair of four-toed legs located behind the base of the head, and range in length from 7 to 27 inches (17 – 69 cm). Unlike greater sirens, lesser sirens have less than 35 costal grooves.[2] Juvenile specimens have red to yellow banding on their heads and stripes running along the main length of the body, although these stripes are absent in Siren intermedia. Adults have plainer coloration; the dorsal side is typically olive green to blue-gray or black, while the ventral is usually light grey. Spotted patterns may also be present in adults.[3] In salamanders, sexual size dimorphism is usually female-biased, but in Siren intermedia, it’s the opposite. Males are the larger sex, and they also have significantly larger heads and enlarged masseter muscles than females.[4]
Lesser sirens are notably neotenic, and possess external gills throughout their lives.[3]
Sources disagree on the number of subspecies within S. intermedia. The majority of the sources in the field agree there are at least two: an eastern and a western variety. Many sources also include a third subspecies, the Rio Grande lesser siren, S. i. texana, but researchers disagree whether the Rio Grande variety belongs as a lesser siren, within S. intermedia, or as a greater siren, within S. lacertina, and some others even consider it to be its own species, as S. texana.[5][6]
Sirens are likely to be found in ponds near other intermittent wetlands. They usually inhabit swamps and ponds, and can survive in dry ponds for up to two years by a process called “aestivating”. Sirens are considered poor overland dispersers because they rarely leave the water, so their geographical distribution is largely determined by pond connectivity and biotic interactions.[7]
Lesser sirens are aquatic salamanders, but their ability to withstand factors like dehydration allows them to have good survival skills in their ephemeral habitats. Sirens are able to osmoregulate and produce a mucoid cocoon during aestivation, which greatly reduces dehydration and electrolyte stress.[8] Their small legs enable them to move on dry land for short periods of time.[9]
The lesser siren is found in the United States and Mexico, primarily from Virginia to Florida, west to Texas, ranging into northeastern Mexico as far as Veracruz, and north to Illinois and southwest Michigan.[1][10] Multiple specimens have recently been rediscovered in Michigan after a 60-year absence.[11][12] Lesser sirens only occur in permanent wetlands, whereas other salamander and frog species can occupy a range of dry and wetlands. Lesser sirens are top predators in permanent wetlands.[13] They can quickly colonize and become dominant consumers in new ponds such as those constructed by beavers. Their ability to aestivate and burrow in soft sediments and live in dense aquatic vegetation in shallow waters facilitates their dominance. In addition, the species’ high productivity, high fecundity, and rapid growth to early sexual maturity allows it reach a high density quickly and easily, and thus establish dominance in the habitat.[14]
The lesser siren is quite common through most of its range, but rarely seen due to its secretive nature. Like almost all species of amphibian, their numbers are believed to be declining due to general reductions in water quality caused by agricultural pesticide and fertilizer runoff. They are frequently collected and used as bait for fishing.
The species was once believed to be extirpated from Michigan,[11] but has been recently rediscovered in limited numbers.[15] The S. i. texana subspecies is listed as a threatened species in Texas. They are listed as Least concern on the IUCN Red List and a species with "Special Protection" in Mexico.[1]
Western Lesser Sirens (Siren intermedia nettingi) have poor eyesight. They rely on their other senses to forage, hunt, and survive.[13]
Sirens rely on chemical cues to detect prey and not on visual cues. The use of chemical stimuli in the detection of prey and predators are common in amphibians. [16]
All species in the sirenidae family are paedomorphic, eel-shaped salamanders that live in aquatic environments. They respire through their gills, lungs and skin, and survive well in hypoxic environments low in oxygen. Siren intermedia is unique among amphibians in its ability to construct a mucoid cocoon that slows down dehydration during aestivation, and the lesser siren can withstand long periods of food deprivation without ill effects. During aestivation, respiration slows down significantly, and gills atrophy over the next 16 or more weeks.[8]
The lesser siren is vocal, unlike most salamanders. The lesser siren is known to emit a series of clicks when it approaches others of its species, or a short screeching sound if handled. Acoustic behavior serves a functional service in S. intermedia, especially since it is nocturnal and it burrows in sediments, swims and crawls through densely vegetated waters. However, ts visual and olfactory senses are very limited in this habitat, and thus the possibility of predation and other risks are high in this case. Nevertheless, acoustic behavior in lesser sirens is still infrequent, and becomes even less frequent with undisturbed habitat residency, perhaps because of their familiarity with the environment.[17]
Siren intermedia make and responds to underwater sounds that may have specific communicational significance. Resting sirens are usually silent, but they may produce trains of pulsed sounds or “clicks”. Their tendency to click is greater in groups than in single specimens, which suggests that they are involved in intraspecific communication. These acoustic behaviors occur most often when other sirens are present. They are emitted at different pulse rates by specimens clicking simultaneously, and are associated with head-jerking motions. Head-jerking may offer visual reinforcement of an acoustically defended individual space, or it may be required for sound production. S. intermedia can produce clicks by moving the horny jaw coverings together rapidly, and head-jerking may be associated with such movement when it is particularly forceful. This means of sound production is similar to the upper and lower teeth of humans, clicking with the mouth open.[17]
Another frequently produced sound ("yelp") is associated with cases of distress, or alarm. When S. intermedia butt or bite each other in their habitat, the bitten or injured individuals may swim away quickly, emitting yelps at frequencies of 880 Hz. These yelp sounds could have communicational significance if they prevent further attack or signal to other individuals that one is injured.[17]
Animals that inhabit freshwater habitats have high-affinity sodium uptake systems. Therefore, the better an animal is adapted to freshwater, the lower the rate of sodium loss and uptake. Sirens have a high sodium affinity (around 0.2 peq/g per day), and thus are able to resist the harmful effects of low-sodium environments.[8]
Insulin has been isolated from the pancreas of lesser sirens that is mostly conserved in sequence as compared to other amphibian orders. However, it does have some substitution differences that indicate that sirens diverged early from other salamanders.[18]
Lesser sirens are filter feeders. They sift through pond bottoms and aquatic vegetation for prey items.[13] They have heavily keratinized beaks and vomerine dental arrays that can inflict substantial wounds.[7] The diet of the lesser siren includes at least 10 different taxa, which includes primarily aquatic invertebrates, including tadpoles and snails. They also eat several insects and their larvae, crayfish, mollusks, amphibians, siren eggs, and algae, although the plant material may be an incidental result of their gape-and-suck feeding style.[19]
The lesser siren is nocturnal, spending its days hidden in the debris and mud at the bottom of slow-moving bodies of water. Sirens are most active in the fall and spring seasons, when water temperatures are close to 15 °C and there is no danger of drought.[20] During the summer months, the ponds and other habitats that the lesser siren live in go through periods of drought, which leads to low water levels and possibly dried-up ponds. The lesser siren’s strategy to withstand the rigors of these dry seasons is something called “aestivation”, or summer dormancy, which can last up to 35 weeks, depending on the severity of the drought. During the sixteen-week period from July to October, aquatic lesser sirens increase the osmotic concentration of their body fluids, and slow down bodily functions.[21]
They do this by burrowing themselves into the bottom of its drying pond in tube-like channels about the length and width of their bodies. For the rest of the aestivating process, they then secrete a mucous cocoon. That is then followed by a significant drop in their oxygen consumption and heart rate. The gills slowly atrophy and the body shrinks, and as a result the fat is metabolized at one-fifth the normal rate. As expected, large individuals store more fat and consume less oxygen per unit weight than small ones, and thus can survive much longer periods of aestivation. Some individuals, especially the smaller sirens during aestivation, die or suffer from dehydration as they are unable to store sufficient fat and the greater metabolic demand reduces their chance of survival.[21]
As the drought season comes to an end, lesser sirens become active within a day, and slowly regain the lost weight over the next 8–11 weeks.[21]
From November to January, males occupy a shelter as a nest site usually surrounded by vegetation or among plant roots, and actively equip it with moss from the surrounding nest site, plucking plant material and dragging it back to the nest site. They then defend their territory aggressively against others through biting.[4]
Though little is known about their courtship, it is believed to be quite violent, as many specimens collected have scarring from healed bite marks from other sirens. About 12-300 eggs are laid at a time, and several clutches may be laid over the course of the year. Hatchlings are only about 0.4 in (1.1 cm) in length, but grow quickly. Maturity is typically reached in approximately three to four years. Courtship includes several repeating behavioral patterns. Once the female approaches the nest site, the male and female start moving within the area, coiling around each other. The male pursues the female’s cloaca closely, sometimes rubbing his head against the flank and the cloacal region of the female. Both the male and the female wave their tail fins by undulating the tail tip.[4]
During oviposition, the female turns on its back, positions the cloaca near the top of the nest cavity and halts for several seconds. Then the male positions his cloaca near the site of oviposition. Eggs are directly coiled into the moss that the male has prepared in the nest. Interlacing of the eggs into the plant material in the nest ensures that the eggs adhere to the nest as a compact mass, and facilitates external fertilization.[4]
In S. intermedia, parental care is fulfilled by the males. Paternal care as observed in the lesser siren is very rare for salamanders. After the female completes oviposition and leaves the nest, the male stays in close proximity to the eggs and takes the responsibility of parental care. The total number of eggs can be around 120–130, with a diameter of about 3 mm. The male constantly moves the egg mass, circles around it, and aerates the eggs through vigorous tail fanning. The tail-fanning behavior of the male towards the eggs can enhance sperm dispersal. Additionally, the male continuously cleans the nest from sand and other materials, to improve hygienic conditions and possibly to prevent infections from pathogens and fungi. It is also likely that males remove dead or infected eggs, in order to prevent further infection of the viable eggs.[4]
The development of the larvae takes approximately 35 days. Paternal care does not end there however, it continues after the larvae hatch and the male continues to aggressively defend the larvae up to one week after hatching.[4]
Siren intermedia has many important effects on community structure as it is one of the most important predators in temporary ponds, where it complements the keystone predator role of eastern newts (Notophthalmus viridescens).[22] S. intermedia reduces the total densities of the anuran larvae, and by doing that, it allows the eastern newts to act as keystone predators over a broad range of prey densities.[7]
Adult mole salamanders (Ambystoma talpoideum) and lesser sirens (Siren intermedia), are the top two predators in temporary ponds of the southeastern United States. Siren intermedia competes with and is an intraguild predator of A. talpoideum, limiting its growth and controlling its recruitment.[7]
The lesser siren (Siren intermedia) 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.
La sirena menor, Siren intermedia, es un anfibio de vida acuática, distribuido entre el este de los Estados Unidos y el norte de México. Recibe varios nombres comunes, como anguila de dos patas, sirena enana y anguila de fango. El epíteto específico denota su tamaño, intermedio entre la sirena mayor, Siren lacertina, y las sirenas enanas, especies de Pseudobranchus.
La sirena menor es de hábitos nocturnos. Durante el día permanece oculta en los sedimentos en el fondo de masas de agua de curso lento. Se alimenta principalmente de invertebrados acuáticos, como gusanos, larvas de insectos, caracoles y crustáceos. También consume huevos de otros anfibios y depreda sobre sus larvas.
La reproducción es ovípara, y tiene lugar entre los meses de febrero y abril. Las hembras son maduras a los dos años, una vez que alcanzan los 15 cm de longitud. Ponen entre 12 y 200 huevos, según la envergadura de la hembra, en depresiones en el sustrato protegidos por la vegetación. Se ha observado que defiende el nido. Aunque muchos ejemplares muestran cicatrices de mordeduras, no se conoce si son parte de las luchas de cortejo. Tampoco se sabe si la fecundación de los huevos es externa o si la hembra recoge el esperma.[2] Las crías miden alrededor de 1,1 cm de longitud, pero crecen rápidamente.
La sirena menor es vocal, a diferencia de la mayoría de las salamandras, y emite una serie de chasquidos cuando se acerque a otras de su especie, o un corto chillido si se la maneja.
Si su hábitat se seca durante el verano, se sabe que estos anfibios soportan las sequías excavando en el barro. Si el barro se seca, son capaces de excretar una sustancia de su piel que las protege de la deshidratación y les permite permanecer enterradas en el barro durante meses hasta que el agua vuelve. Sus pequeñas patas les permiten moverse en tierra firme durante cortos períodos de tiempo.[3]
Las sirenas menores tienen cuerpos alargados que poseen sólo dos extremidades, un par de patas, con cuatro dedos, ubicadas detrás de la base de la cabeza, y tienen una longitud que oscila entre 17 - 69 cm (7 y 27 pulgadas). Los ejemplares juveniles tienen bandas rojas o amarillas en la cabeza y franjas que recorren la longitud del cuerpo, aunque estas franjas están ausentes en Sirena i. intermedia. Los adultos tienen una coloración más clara; la parte dorsal es típicamente de verde oliva a gris azulado o negro, mientras que el vientre es generalmente gris claro. Los patrones punteados de los juveniles también pueden estar presentes en los adultos.[4]
Las sirenas menores son notablemente neoténicas, y poseen branquias externas durante toda su vida.[4]
La sirena menor se encuentra en los Estados Unidos y México, principalmente de los estados de Virginia a Florida, al oeste de Texas, y se extiende por el noreste de México hasta Veracruz, al norte de Illinois y al suroeste de Michigan.[1][5] Múltiples especímenes han sido recientemente redescubiertos en Michigan después de una ausencia de 60 años.[6][7]
Diferentes fuentes no están de acuerdo en cuanto al número de subespecies dentro de S. intermedia; la mayoría está de acuerdo en que hay al menos dos: una variedad oriental y otra occidental. Muchas fuentes también incluyen una tercera subespecie, la sirena menor del Río Grande, S. i. texana, pero los investigadores no están de acuerdo en que la variedad del Río Grande pertenezca a la sirena menor, dentro de S. intermedia, o como sirena mayor, dentro de S. lacertina, y algunos otros incluso la consideran especie propia, como S. texana.
La sirena menor es bastante común en la mayor parte de su rango, pero rara vez se ve debido a su naturaleza oculta. Como casi todas las especies de anfibios, se cree que su número está disminuyendo debido a las reducciones generales de la calidad del agua causadas por la escorrentía de los pesticidas y fertilizantes agrícolas. Se recogen con frecuencia y se utilizan como cebo para la pesca.
Se creía que la especie se había extinguido en Michigan,[6] pero ha sido recientemente redescubierto en un limitado número.[8] La subespecie S. i. texana está catalogada como una especie amenazada en Texas. Está incluida en la Lista Roja de la UICN como de menor preocupación y es una especie con "protección especial" en México.[3]
Datos: Q2274144
Multimedia:
Especies: Siren intermedia
La sirena menor, Siren intermedia, es un anfibio de vida acuática, distribuido entre el este de los Estados Unidos y el norte de México. Recibe varios nombres comunes, como anguila de dos patas, sirena enana y anguila de fango. El epíteto específico denota su tamaño, intermedio entre la sirena mayor, Siren lacertina, y las sirenas enanas, especies de Pseudobranchus.
Siren intermedia Siren generoko animalia da. Anfibioen barruko Sirenidae familian sailkatuta dago, Caudata ordenan.
Siren intermedia est une espèce d'urodèles de la famille des Sirenidae[1].
Cette espèce se rencontre[1] :
Multimedia w Wikimedia Commons Syrena mniejsza (Siren intermedia) – gatunek płaza ogoniastego z rodziny syrenowatych.
Zwierzę cechuje się wydłużonym ciałem. Można podzielić je na trzy główne części: głowę, tułów i ogon. Granice pomiędzy nimi wyznaczają podstawa czaszki i kloaka. Osobniki zmierzone przez Gillisa mierzyły od 33,7 do 38,1 cm długości, średnia wyniosła 36,3 cm. 5-6% tych wartości przypada na głowę. Tułów stanowi od 59 do 65% całkowitej długości ciała. Jego przednia część jest wąska. Odchodzą od niej niewielkie, zredukowane przednie kończyny. Leżą one około 2 cm za podstawą czaszki. Za łapami tułów grubieje, osiągając maksymalną grubość 7% długości ciała. Następnie robi się coraz cieńszy. U podstawy ogona osiąga już grubość równą tylko 4-5% długości ciała, a więc mniej więcej tyle, ile w miejscu odejścia kończyn przednich. Ogon jest spłaszczony bocznie, bardziej na odcinku dystalnym. Obejmuje 29-35% długości ciała[2].
Ilość kręgów nie jest u tego gatunku stała. Gillis zbadał pod tym względem 4 osobniki, z których trzy cechowały się podobną budową kręgosłupa. Miały od 94 do 96 kręgów, natomiast czwarty miał ich 74. Co więcej, był on dłuższy od pozostałych. Długość pojedynczego kręgu waha się w granicach 0,1-2% długości ciała. Zależy ona od osobnika (duży osobnik o mniejszej ilości kręgów miał oczywiście kręgi większe) oraz od pozycji w kręgosłupie. Kręgosłup rozpoczyna się trzema niewielkimi kręgami, ich rozmiary rosną w kierunku dystalnym. Po nich następują kręgi większe, które jednak nie różnią się zbytnio wielkością między sobą. Różnice wielkości pojawiają się ponownie dopiero w ogonie. Kręgi odcinka ogonowego zmniejszają się w kierunku dalszym, w końcu widać je tylko na fotografii rtg prześwietlonej od tyłu[2].
Receptory tworzące linię boczną rozmieszczone są pojedynczo[3]
Syrena mniejsza porusza się dzięki falistym ruchom ciała. Zazwyczaj przemieszcza się ona w okolicy dna zbiornika[2].
Gillis badał zwierzęta poruszające się z prędkością od 0,3 do 1,5 długości na s. Zauważył on, że w tym przedziale syrena mniejsza potrafi utrzymać pozycję przez kilka cykli związanych z uderzeniami ogona, zwracając uwagę na trudności płaza z utrzymaniem danej pozycji. Największa zaobserwowana przez niego szybkość wynosiła 1,85 długości na s[2].
Za dnia Siren intermedia ukrywa się wśród roślin i odpadków[1].
W przypadku wyschnięcia zbiornika wodnego zwierzę potrafi drążyć w dnie[1]. Zagrzebana w mule, potrafi przetrwać suszę[4]
Syrena mniejsza składa jaja w środowisku wodnym. Umieszcza je w mule na dnie zbiornika wodnego w niewielkim pakiecie bądź w jamce pokrytej odpadkami[1].
Syrena mniejsza żyje na kontynencie północnoamerykańskim. W Stanach Zjednoczonych występuje w pasie przybrzeżnych równin od stanu Wirginia aż do środkowej Florydy i wschodniego Teksasu na południe, na północ zaś sięga południa Michigan. W USA zwierzę występuje pospolicie. W Meksyku płaz zajmuje północne części stanów Tamaulipas i Veracruz (w przypadku tego ostatniego stanu istnieje jedynie kilka doniesień o obecności Siren intermedia, dlatego też International Union for Conservation of Nature widzi konieczność potwierdzenia ich kolejnymi badaniami)[1].
Siedliskami tego płaza są płytkie, ciche zbiorniki wodne o względnie ciepłej wodzie. Mogą być one mętne. Rośnie w nich bujna roślinność. Z wód stojących IUCN wymienia wśród nich bagna, tereny podmokłe, stawy, jeziora, rowy. Podaje też, że w mniejszym stopniu syrena ta spotykana jest w rzekach i strumieniach[1].
Gatunkowi nie zagraża wyginięcie. IUCN przypisuje syrenie mniejszej status gatunku najmniejszej troski (LC – Least Concern). Uzasadnia to szerokim zasięgiem występowania tego płaza i, prawdopodobnie, wysoką liczebnością populacji, a także małym prawdopodobieństwem szybkiego spadku liczebności populacji[1].
W USA temu pospolitemu tam gatunkowi nie zagraża niebezpieczeństwo wyginięcia. Status płaza w Meksyku wymaga dodatkowych badań terenowych. Jednakże wiele lokalnych populacji zostało uszczuplonych, a nawet przestało istnieć. Wiązało się to z utratą siedlisk[1].
Wśród zagrożeń dla tego gatunku IUCN wymienia rolnictwo i urbanizację. Powodują one utratę bądź zmiany w środowisku zamieszkiwanym przez syreny[1].
Gatunek znajduje się pod ochroną gatunkową w Meksyku. Jego zasięg występowania obejmuje również kilka obszarów chronionych[1].
Gillis w swych badaniach trzymał syreny w wodzie o temperaturze 19,5±0,5 °C, 12 h w świetle i 12 h w ciemności. Płaza można karmić dżdżownicami z rodzaju Lumbricus[2]
Syrena mniejsza (Siren intermedia) – gatunek płaza ogoniastego z rodziny syrenowatych.
Siren intermedia é uma espécie de anfíbio caudado pertencente à família Sirenidae. Pode ser encontrada nos Estados Unidos e no México.
Siren intermedia é uma espécie de anfíbio caudado pertencente à família Sirenidae. Pode ser encontrada nos Estados Unidos e no México.
Den mindre sirenen (Siren intermedia) är en ållik art i ordningen stjärtgroddjur.
Arten har en kraftig, slemmig och ålliknande kropp som är olivgrön till svartbrun med ljusare undersida samt med svarta och ljusa fläckar. Huvudet saknar tänder, men har näbbliknande bitytor. Huvudet har rödaktiga, buskiga yttre gälar. Könen är helt lika.[3] Den saknar bakfötter och har små framfötter med fyra tår. Arten uppnår en längd mellan 18 och 68 centimeter.[4]
Den mindre sirenen finns från norra delarna av delstaterna Tamaulipas och Veracruz i Mexico, över USA:s sydkust från östra Texas till centrala Florida, och via Mississippidalen norrut upp till södra Michigan.[2]
Arten lever hela sitt liv i lugna, grunda och varma vatten med riklig vegetation, som diken, bäckar, bevattningskanaler och sankmarker. I vattensamlingar där den mindre sirenen och dess nära släkting armsalamandern delar utrymme, tenderar denna art att hålla sig till de surare delarna. Den är i huvudsak nattaktiv och tillbringar dagen gömd i bottenslammet eller under klippor och stenar. Födan består framför allt av bottenlevande djur som kräftdjur, snäckor, insektslarver och rundmaskar. Vissa forskare anser att även småfisk kan ingå i dieten, men det betvivlas av andra. Den längsta livslängden för ett exemplar i fångenskap är 7 år.[5]
Litet är känt om fortplantningen, men den antas vara extern. Under tidig vår lägger honan mellan 12 och över 300 ägg i fördjupningar i bopttenslammet i de vattensamlingar hon lever i.[4] Äggen kläcks efter omkring 1,5 till 2,5 månader. Ungen är könsmogen efter omkring 2 år.[5]
Den mindre sirenen är klassificerad som livskraftig ("LC"), men litet är känt om populationsförändringarna. Det har konstaterats att lokala populationer har minskat eller försvunnit till följd av våtmarksförluster. Industriell utbyggnad och urbanisering betraktas som potentiella hot.[2]
Den mindre sirenen (Siren intermedia) är en ållik art i ordningen stjärtgroddjur.
Загальна довжина досягає 35—68 см. Голова витягнута. Тулуб довгий вугреподібний з рудиментарними передніми чотирипалими короткими лапами. Має по 3 пари невеликих зябер. Голова та зябра червонуваті. Забарвлення коливається від оливково-зеленого до темно-коричневого кольору з більш світлим черевом, з чорними і яскравими плямами.
Полюбляє ставки, озера, стариці, зрошувальні канали і болота. Активен вночі. Часто ховається у мулі. Перебуває майже весь час у воді. Харчується тритонами, амбістомами, пуголовками, ракоподібними, равликами, личинками комах і круглими хробаками.
Статева зрілість настає у 3—4 роки. Самець під час шлюбного періоду здатен видавати гучні звуки на кшталт клацання. Самиця відкладає ікру на різні водні рослини. відкладається до 300 яєць. За рік буває декілька кладок. Личинки з'являються через 1,5—2 місяці.
Тривалість життя до 7 років.
Мешкає у США: штатах Вірджинія, Північна Кароліна, Південна Кароліна, Джорджія, Флорида, Алабама, Міссісіпі, Луїзіана, Арканзас, Техас, Оклахома, Теннессі, Кентуккі, Міссурі, Іллінойс, Індіана, Огайо і Мічиган; а також у Мексиці — штати Тамауліпас і Веракрус.
Siren intermedia là một loài trong họ Sirenidae, có nguồn gốc ở miền đông Hoa Kỳ và phía bắc México. Chúng được gọi bằng nhiều tên gọi thông thường như cá chình hai chân, siren lùn và lươn bùn. Loài này là loài trung gian giữa Siren lacertina và Pseudobranchus spp.
Siren intermedia được tìm thấy ở Hoa Kỳ, chủ yếu từ Virginia đến Florida, phía tây đến Texas (dao động vào vùng đông bắc México như Veracruz) và phía bắc đến Illinois, Indiana và Michigan.
Bài viết Bộ Có đuôi này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn. Siren intermedia là một loài trong họ Sirenidae, có nguồn gốc ở miền đông Hoa Kỳ và phía bắc México. Chúng được gọi bằng nhiều tên gọi thông thường như cá chình hai chân, siren lùn và lươn bùn. Loài này là loài trung gian giữa Siren lacertina và Pseudobranchus spp.
Ка́рликовый си́рен[1] (лат. Siren intermedia) — хвостатое земноводное из семейства сиреновых.
Общая длина достигает 35—68 см. Голова вытянута. Туловище угревидное с рудиментарными передними четырёхпалыми короткими лапами. Имеет по 3 пары небольших жабр. Голова и жабры красные. Окраска колеблется от оливково-зелёного до тёмно-коричневого цвета с более светлым брюхом, с чёрными пятнами.
Любит пруды, озёра, старицы, оросительные каналы и болота. Активен ночью. Часто скрывается в иле. Находится почти всё время в воде. Питается тритонами, амбистомами, головастиками, ракообразными, улитками, личинками насекомых и круглыми червями.
Половая зрелость наступает в 3—4 года. Самец во время брачного периода способен издавать громкие звуки вроде щелчков. Самка откладывает икру на различные водные растения. Откладывается до 300 яиц. За год бывает несколько кладок. Личинки появляются через 1,5—2 месяца.
Продолжительность жизни до 7 лет.
Обитают в США: штаты Вирджиния, Северная Каролина, Южная Каролина, Джорджия, Флорида, Алабама, Миссисипи, Луизиана, Арканзас, Техас, Оклахома, Теннесси, Кентукки, Миссури, Иллинойс, Индиана, Огайо и Мичиган; а также в Мексике — штаты Тамаулипас и Веракрус.
Ка́рликовый си́рен (лат. Siren intermedia) — хвостатое земноводное из семейства сиреновых.
