The Himalayan Salamander

The Himalayan Salamander (Tylototriton verrucosus Anderson, 1871) is the only species of salamander found in India. It is a unique and rare, tailed amphibian (Order Urodela/Caudata) which is endangered and protected under Schedule II part II of the Indian Wildlife Protection Act, 1972. It is a keystone species of the lentic habitats in the eastern Himalayas. It is a member of the ancient family Salamandridae, members of which were known to exist in Europe from the Jurassic era.
It occurs between the altitudes of 1330-2220 metres a.s.l in the Shiwalik, Mahabharat and Chulachuli hills of Eastern Nepal and in the Darjeeling sub-division of West Bengal (India) besides in Bhutan, Kamalang valley in Lohit district of Arunachal Pradesh (India), Ukhrul and Senapati districts of Manipur (India), Kakhein hills of Myanmar, Loei and Chiang Mai provinces of Thailand and in Western China. It is mostly known to inhabit the cloud forests and cool mountain lakes and temporary as well as permanent pools in the Eastern Himalayas. However, wherever it is found, it is threatened and its future is uncertain. It makes a low noise while snapping its jaws, giving its Nepali name ‘pani kukur’ and its Thai name ‘mah nam’ both of which mean ‘water dog’. The Gorkhas of North Bengal call it ‘gorho’.
The adult Salamander
Characteristics of the Adult
Males are 14-17 cm in length. Females are 10-20% bigger (15-20 cm) and more robust. Somewhat lizard-like in appearance, both have a large obtusely triangular and flattened head. The head is slightly broader than long. The lateral cranial ridges on the head curve inwards in front of the parotoids. The snout is short and rounded and the upper jaw covers the lower one. Nostrils are semi-circular and widely separated, situated near the tip of the snout and provided with a valvular skin-flap for closing. The eyes are lateral, of moderate-size and projecting, provided with eyelids, the upper eyelid is prominent. The ear-drums are indistinct. The body is cylindrical, with four short stumpy limbs of equal size and a long tail like that of a crocodile. Hence it is sometimes called Crocodile Salamander because of its resemblance to a minute-sized crocodile. The limbs are short and appear to be weak, with 4 fingers in the fore limbs and 5 toes in the hind limbs. The fingers and toes are without webs, nails or claws. There is a prominent broad median porous vertebral ridge commencing from the end of the cranial ridges and terminating at the root of the tail. There are longitudinal series of 15-16 knob-like porous glands on each side of the body, the last 3-4 positioned behind the leg when it is extended at fight angles to the body. The cloacal slit is ventral and longitudinal, the borders are not much swollen except in the
breeding season. The tail which is almost as long as the head and
body (80-95 mm) is laterally compressed. The tail height is more in males. The skin is rough and tubercular and covered with a slime secreted by the skin glands.
The colour is chocolate brown with pale orange on the lips, lower jaw, chin, throat and on the palm and sole of the feet. The cloaca is deep orange during the breeding season (more so in females) and the lower edge of the tail is dull orange-yellow (see Photos 1-2). In pools in which it lives its colouration blends well with the background.
Age at Sexual Maturity
The male attains maturity when it reaches 12-14 cm. The female reaches maturity when it reaches 15-16 cm. Males reach sexual maturity at considerably smaller sizes than females. Sexual maturity is often attained by the third year but mostly during the fourth year. No evidence of neoteny was detected in captivity or in nature.
Maximum Age known
The maximum age known is 11 years but the most frequent age class is 5-7 years.
Habitat of the Salamander
Adults live in diverse habitats leaf-litter on the forest floor and at the edge of woods, meadows and pasturelands covering the banks of mountain ponds and lakes, tea estates, vegetable gardens at the backyard of human habitations, rice fields, boulder strewn hill streams and flooded rock poois at an altitude of 1330-2220 metres above mean sea level.
These areas experience a warm wet summer from March to October (air temp: 18-27degreeC) and a mild wet winter from November to February (air temperature 7-16 degree C) besides an annual rainfall of 1300-1400 mm, most of which falls between June-July (800-900 mm) and August-September (400-500 mm).
During the breeding season (April to September) they generally inhabit shallow permanent or temporary pools, shallow ditches, marshes and slow-moving streams of high hills which abound with aquatic plants and are exposed to sufficient sunlight. Submerged aquatic vegetation in such pools in the Darjeeling hills comprise of Poa spp, Hydrocotyle asiatica while semi-submerged vegetation includes Polygonum glabrum, P. aula, Cyperus cephalotus, C. rotundus and Scirpus artriculatus. The edge of the pools are covered by low bushes and exotic weeds like Eupatorium glandulosum, Lantana camara etc which have invaded the pasturelands and meadows.
Reproduction takes place in different waterbodies ranging from small rain puddles to permanent lakes. Their depth is maximal during monsoon season (0.5-2 in). After the monsoon these poois are partially or totally dry with water level falling to 15-30 cm, the water becoming very dirty. The water quality varies from time to time and sometimes becomes highly acidic (pH 4-6) and oxygen concentration varies from 5-10
ppm, during early April-May. During the winter and early summer the salamanders hide under rotten leaves in rock pools, under logs, stones and dry soil below roots and dead tree trunks near water. They are capable of short migrations on’ land, atleast several hundred metres. Prior to the monsoon rains, many streams dry up or are reduced to a narrow trickle. However, small rock pools are not uncommon
particularly in the vicinity of villages. Lurking in the crevices between the large partially submerged boulders, the salamander shares its niche with typical mountain brook frogs as well as aquatic insects like Belostoma, Ranatra, Perla, Ephimera and Anax. The salamander is an excellent example of camouflage and concealment and is rather difficult’to locate in the rock pool as it blends with the water weeds.
After the onset of the monsoon early in June, the hillsides acquire a green lushness which contrasts strikingly with the appearance during the dry season. The streams and pools are again flooded in monsoon, providing a formidable habitat for the larval stages of the Himalayan salamander. Although spatial distribution of populations of the salamander in the Darjeeling hills is sporadical, local abundance is sometimes as high as 2-3 individuals per sq m of lake or pond area during the breeding season in monsoon.
Food of the Adult
Adult diet consist of aquatic insects like Dytiscid beetles; Gastropod and Bivalve molluscs (Sphaerium indicum); Decapod crustaceans (land crabs - Potamon potamiscus sikkimense); Lumbricid and Megascolecid earthworms; larvae and pupae of Diptera and Coleoptera and nymphs of Odonata, besides tadpoles of common amphibians and eggs from foam-nests of Rhacophorid frogs. At Namthing (Darjeeling district) we observed that occassionally a salamander will swim up from the depth of the lake to capture tadpoles of the toad (Bufo himalayan us) or the tree-frog (Polypedates teraiensis) swimming at the surface.
At Pacheng and Sonada (Darjeeling district), the adults often took shelter among bamboo stumps and
fed on snails, slugs, earthworms, termites, wood-lice and coprophilous insects infesting the rotten bamboo vegetation. They appeared to have a broad unspecialized diet. In the monsoon months, food items comprised of both aquatic and terrestrial elements. Aquatic prey taxa predominated during times of heavy rainfall (June-July) but during periods of low rainfall (August-September) terrestrial prey taxa predominated in males and aquatic prey taxa in females. Compared to females, the diet of males are more of terrestrial prey taxa at any time.
General Habits of the Adult
They are secretive creatures which are mostly seen during the rainy season between May and October when the otherwise terrestrially inclined species enters water and congregate at the edge of the pools to lay their eggs. Sometimes these sluggish creatures hide under stones. When stones are removed they are found dazed and startled and remain calm and quiet for a few seconds but later dart off into the water and escape. They swim slowly by the undulatory motion of their tail, the legs being turned backwards but
when they float on the surface of water, they sprawl out their limbs. They crawl at the bottom of pools with their legs and occassionally come up to the surface at intervals of 3-4 minutes to gulp air with their mouth and dive down to the bottom again. At night they leave the water and move around actively on land, more so during the breeding season in May-June. They shed their skins which comes away in shreds every fortnight. They have good power of regeneration, regrowing bitten off legs.
They are predominantly terrestrial in their non-reproductive period but aquatic in their reproductive
period. During June-July both sexes enter water. In August-September (post-breeding period) males move back to land while females stay in water. As a consequence, males are encountered more on land than females in August-September. The adults come out of their hibernating places and enter water as soon as the first spring showers fall in March or April. Spawning occurs between May to July and by the end of October even the females leave the pools. The courtship and mating sequence is very elaborate and interesting.....

By:/ Kaushik Deuti and V.D Hegde

Comments

Popular posts from this blog

ENVIRONMENTAL POLLUTION: ECOLOGICAL IMBALANCE AND RELATED HEALTH HAZARDS

6 oldest universities of modern India