15 Main Types of Amphibians (With Diagram)

The following points highlight the fifteen main types of amphibians. The types are: 1. Giant Salamander (Family Cryptobranchidae) 2. Cryptobranchus (Family Cryptobranchidae) 3. Necturus (Family Proteidae) 4. Proteus (Family Proteidae) 5. Siren (Family Sirenidae) 6. Amphiuma (Family Amphiumidae) 7. Ambystoma (Family Ambystomatidae) 8. Triturus (Family Salamandridae) and Others.

Type # 1. Giant Salamander (Family Cryptobranchidae):

Megalobatrachus (Fig. 7.29A) is a giant salamander of China and Japan. It attains a length of about 1.65 m. All traces of gills or gill-slits disappear, but two branchial arches persist. The eyes are devoid of eyelids. The limbs are functional with four digits in the forelimbs and five digits in the hind limbs.

Type # 2. Cryptobranchus (Family Cryptobranchidae):

Cryptobranchus (Fig. 7.29B) is called the ‘hell bender’ of the United States. There is a single branchial aperture (spiracle) on the left side only and is used for the outlet of water during respiration. Four branchial arches are present. Like that of Megalobatrachus, the limbs are functional. The eyes are lidless. The skin on the dorsolateral sides of the body shows flabby folds.

Type # 3. Necturus (Family Proteidae):

Necturus is a permanent larval salaman­der with persistent external gills (Fig. 7.29H) and lateral line sense organs. It obtains a length of about 45 cm. The trunk is elongated and the tail is laterally compressed with con­tinuous median fin.

The limbs are small and feebly developed. There are four digits in each limb. The eyes are small with no eyelids. Two gill-slits are present. The lungs are greatly reduced. The colour is grey to rusty or dark brown. Three pairs bushy, plume-like external gills are present throughout life.

Habit and Habitat:

They are nocturnal, hiding during the day under stones or buried in the mud. They con­sume worms, insect larvae, Cray fishes, small fishes and frog’s eggs. Before winter they mate, and the females guard the eggs.

Species:

N. maculatus occurs in the eastern parts of United States. N. punctatus is found in the North and South Carolina.

Type # 4. Proteus (Family Proteidae):

The body is eel-like with a laterally com­pressed tail. The head is broad with a blunt snout. The colour is translucent white and the eyes remaining completely hidden in the skin are excellent adaptations which compel them to become cave dwelling salamanders.

The limbs are ill-developed. The forelimbs are provided with 3 toes and hind limbs bear 2 toes. There are 3 pairs of feathery gills, generally called ‘Olm’. ‘Olm’ means cave dwelling salamander of genus proteus used in German. The body attains a length of 30 cm.

Habit and Habitat:

They feed on small aquatic crustacean and small fish. The female sometimes lays 30- 40 eggs if temperature changes. They can live at least 25 years.

Species:

It has a single species—P. anguineus. It lives in the underground rivers of Carolina, Carinthia (South Asia) and in the caves of Western Yugoslavia.

Type # 5. Siren (Family Sirenidae):

Siren has an elongated eel-like body with­out any trace of hind limbs. They have 3 pairs of external fringed gills and 3 pairs, gill openings. The forelimbs are well-developed.

A prominent vomeronasal organ (or organ of Jacobson) is present. The length of the body is about 70 cm.

Habit and Habitat:

They live in the ponds and ditches of USA.

Species:

It has two species—the Greater Siren (Siren lacertina) and Lesser Siren (S. inter­media). Necturus, Proteus and Siren are per-ennibranchiate or persistent gilled animals.

Type # 6. Amphiuma (Family Amphiumidae):

Amphiuma has an eel-like body and becomes 90 cm in length. It is a semi-larval creature with lungs and rudimentary limbs. The eyes are devoid of eyelids. They have no external gills, but two pairs of gill-slits are retained throughout life.

Habit and Habitat:

They mate in May and hatching takes place during November and December. The males construct a nest in which the females lay eggs. They feed on cray fishes, molluscs and small fishes.

Species:

It has two species—two toed amphiuma (A. means) and three toed amphiuma (A. tridactyla). They live mostly in N. America and also in the southern parts of America.

Type # 7. Ambystoma (Family Ambystomatidae):

Ambystoma (or Amblystoma) is a North American terrestrial newt. The body is mode­rately stout with fore digits in the forelimbs and five digits in the hind limbs. The head is depressed and the mouth is wide.

Species:

The genus Ambystoma represents 11 species and they differ themselves in colour pattern. They range from Alaska to Mexico, the whole of Northern Asia and southern part of China. One asiatic species A. persimile is found in the upper mountain of Myanmar and Thailand.

Tiger Salamander (A. tigrinum) is found from New York to California and to Central Mexico. It is recognised by dark brown or bluish brown body with numerous spots. The famous larva of A. tigrinum is Axolotl. The name axolotl stems from an ‘Aztec’ word meaning water monster. Another species are European spotted salamander, A. opacum and Mexican Axolotl, A. maxicanum, etc.

Axolotl Larva:

Larvae of two genera of urodeles, Ambys­toma and Triturus have the power of developing the sex organs and thus are able to reproduce at the premature stage. This phenomenon of attainment of sexual maturity in larval phase is called neoteny. Such neotenous larval phase is exhibited by Axolotl larva (Fig. 7.29E).

The Axolotl larva of Ambystoma has a well-developed postanal tail with a continuous tail fin un­supported by fin-rays. It has three pairs of exter­nal gills and four pairs of gill-slits.

The cause of retention of larval characters and the absence of metamorphosis from aquatic to land life, appears to be due to abundance of food, lack of iodine in water and other favourable conditions of life. The axolotl becomes sexually mature at the age of about six months. It breeds several times a year. The axolotl is found in that stage in different parts of the United States.

The axolotl is known since long time. It was regarded first to be related to a per-ennibranchi­ate form, specially to Siren and gets the name Siredon axolotl or Siredon pisciformis.

But in 1865 some such specimens were transported from the United States to France where they started to breed and finally underwent meta­morphosis. They lost the gills and other larval features and transformed into adult Ambystomas. Since then, the Axolotls are identified as the sexually mature larvae of Ambystoma.

Type # 8. Triturus (Family Salamandridae):

They are commonly called “Newts”. Newts are amphibians of the salamander family. The name comes from the Anglo-Saxon ‘evete’ which became ‘ewt’ and finally a ‘newt’ from the transcription of the ‘n’ in an ‘nwt’. in U.K., newt calls solely to the genus Triturus but in N. America, the term is applied to related animals which are sometimes confusingly called “sala­manders’.

Newts of the genus Triturus is found in Asia, North Africa, Europe and N. America. They have laterally compressed tail and fore­limbs with four digits and five digits in the hind limbs. The eyes are provided with eyelids. They develop a crest during spawning season. Fertilization is internal. After fertilization, the female lay about 200-300 eggs on leaves of aquatic vegetation.

Food:

They eat worms, snails and insects when on land, but insect larvae when in water.

Species:

The genus includes 18 species of which 12 are European. Some of them are smooth newt, T. vulgaris; Alpine newt, T. alpestris and Crested newt, T. cristatus; Marbled newt, T. marmoratus, etc.

Type # 9. Salamandra (Family Salamandridae):

Salamandra (Fig. 7.29C) is the European land salamander with a sub-cylindrical tail. There is no trace of either gill or gill-slit in adults. The branchial arches are greatly reduced. Two pairs of limbs are present. The forelimbs are provided with four digits and the hind limbs are with five digits. The vertebrae are of opisthocoelous type.

The vomerine teeth are present on either side of the Para sphenoid. Salamandra maculosa (Spotted sala­mander) is viviparous and the youngs emerge directly as larvae. The skin contains poisonous glands which eject white poisonous fluid. Salamandra atra is also a viviparous form and produces two young’s at a time. While intra­uterine, the young’s develop external gills which absorb oxygen and nutrition.

Habit and Habitat:

They are sluggish in nature and feed on worms, snails, insects and some crusta­ceans.

Distribution:

The fire salamander (Salamandra salamander Fig. 7.30A) is found in France, Spain, Central and Southern Europe through to Asia Minor. Salamandra atra occur in Germany, Austria and Yugoslavia.

Type # 10. Crocodile Salamander (Family Salamandridae):

Tylototriton or crocodile salamander (Fig. 7.30B) is about a length of 15-20 cm and lizard-like body with a laterally compressed tail. The head is flattened and bears two ridges on the dorsolateral sides.

The genus contains 7 species of which T. verrucosus is the only Indian species and occurs in Arunachal Pradesh, some parts of Darjeeling district (W. Bengal), Manipur, and Sikkim at altitudes between 1260-2220 m. The colour of the Indian species is black brown above and pale yellow below. 15-16 knob-like porous glands are along the mid-vertebral ridge on each side. The anal opening is longitudinal.

Habit and Habitat:

During winter season they hide in the hole and hibernate. From April to August, the sala­manders wander on land, and this time is the breeding season. They pre­fer to swampy areas and are found in pools and bogs. They feed on insect larvae, earthworms and tadpoles. T. andersoni is found in Okihawa Islands of Loochoo Archipelago.

Occurence in W. Bengal:

Indian salamander is confined to two pools, one near Sukhiapokhri (altitude 1850 metres) and the other at Sonada (altitude 1660 metres) in the Darjeeling district of W. Bengal. At present it is scarcely available and is believed to be on the verge of extinction.

Chromosome Number:

Chatterjee, K. and Majhi, A. (1974) repor­ted that the diploid chromosome number is 24 in T. verrucosus. In T. andersoni 2n = 24 has been cytological investigated so far. The diploid chromosome number in all of the sixteen cytological known salamander species and in Indian salamander consists of 24 in both sexes.

There is a marked absence of acrocentric and telocentric chromosomes in all the members of the family salamandridae. In all urodeles, the sex chromosomes are not diffe­rentiated morphologically from the autosomes and this is consistent with current concept that in general there is no morphological differen­tiation of sex chromosomes in Amphibia.

Type # 11. Hyla (Family Hylidae):

Hyla is a tree-frog. The terminal phalan­ges are claw-like and swollen at the base to form adhesive pads by which it can climb the trees or vertical walls of the buildings or rocks. The upper jaw is toothed. All the tree-frogs, excepting Hyla arborea of Southern China, an exclusively restricted to America or Australia.

Hyla venulosa of the lower Amazon can glide from a considerable height. Parental care is well-developed in this genus. H. faber makes mud nests for laying the eggs and female H. goeldii carries the eggs on its back. Only Indian hyla, Hyla annectans is found in some parts of Meghalaya and Assam.

Type # 12. Kaloula Pulchra (Family Microhylidae):

They are about 50 mm in length. They are highly colourful toads. Dorsum is black brown to greyish brown with brown or light spot patches with black at the flank. The abdomen is light brownish or white and spotted with grey.

Habit and Habitat:

They are burrower and nocturnal in habits. They can hop well and are good swim­mers also. They eat mainly termites. They occur in India, Sri Lanka, Bangladesh, Pakis­tan, S. China, Japan and Malay Peninsula. It is the most beautiful frog in India.

Type # 13. Scaphiopus (Family pelobatidae):

Their common name derives from the presence of a sharp edged tubercle of the hind limbs, used for digging purpose in soft soil. They are rough skinned, and are adapted for life in dry habitats. They are found on the sur­face of the ground only in moist weather which takes place after a heavy rain, They are found in N. America.

Type # 14. Bombinator (Family Discoglossidae):

Bombinator (= Bombina) is generally called “Fire bellied toad of Europe”. The length of body is about 5 cm. Its dorsal surface is highly coloured to conceal from predators. The skin emits a toxin which induces vomiting, so the predators avoid it.

When attacked by predators they expose their abdomen and under surface of the limbs to show the bright warming colours. They are found in pools and streams. The genus contains 4 species which occur in Europe and Asia.

Type # 15. Astylosternus (Family Ranidae):

The males possess extensive vascular filaments or hair-like cutaneous papillae on flanks, thighs and groins. The filaments deve­lop especially during the breeding season. During reproduction when the demand of O₂ is greater, it makes up through these filaments. Astylosternus (Trichobatrachus) robustus occurs in E. Africa.