Sunday, July 1, 2012
Caecilians completely lack limbs, making the smaller species resemble worms, while the larger species with lengths up to 1.5 m (4 ft 11 in) resemble snakes. The tail is short or absent, and the cloaca is near the end of the body. Their skin is smooth and usually dark-matte, but some species have colorful skins. Inside the skin are calcite scales. Because of these scales, the caecilians were once thought to be related to the fossil Stegocephalia, but they are now believed to be a secondary development, and the two groups are most likely unrelated. The skin also has numerous ring-shaped folds, or annuli, that partially encircle the body, giving them a segmented appearance. Like other living amphibians, the skin contains glands that secrete a toxin to deter predators. The skin secretions of Siphonops paulensis have been shown to have hemolytic properties
In Sri Lanka, three species occur, and all are found in almost all habitats, preferring moister ones. The most common is Ichthyophis glutinosus, which is found in almost all altitudes; the others are I. orthoplicatus, which is found in similar habitat to I. glutinosus, but is never found in lowlands below 460 metres (1,510 ft); and I. pseudangularis, found in lowlands below 1,200 metres (3,900 ft).
The mating system of the golden lion tamarin is largely monogamous. When there are two adult males in a group only one of them will mate with the female. There are cases of a male mating with two females, usually a mother and daughter. Reproduction is seasonal and depends on rainfall. Mating is at its highest at the end of the rainy season between late March to mid-June and births peak during the September–February rains.
Females are $exually mature between of 15–20 months but it isn't until they are 30 months old when they can reproduce. Only dominant females can reproduce and will suppress the reproduction of the other females in the group. Males may reach puberty by 28 months. Tamarins have a four month gestation period. Golden lion tamarin groups exhibit cooperative rearing of the infants. It is due to the fact that tamarins commonly give birth to twins and to a lesser extent, triplets and quadruplets.
A mother is not able to provide for her litter and needs the help of the other members of the group. The younger members of the groups may lose breeding opportunities but they gain parental experience in helping rear their younger siblings. In their first 4 weeks, the infants are completely dependent on their mother for nursing and carrying. By week five, the infant spend less time on their mother’s back and begin to explore their surroundings. Young reach their juvenile stage at 17 weeks and will socialize other group members. The subadult phase is reached at 14 months and a tamarin first displays adult behaviors
Life span in captivity has been as high as 25 years whereas life span in the wild is about 13–16 years. The wild population is estimated at about 6000, with 2000 adults. This species is critically endangered, having lost more than three-quarters of its original habitat to deforestation. Clearing of forest habitat by humans is the main problem and populations have also been depleted by the pet trade and scientific research. They are now protected by international law; although they are numerous in captivity, they are still critically endangered in the wild