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CHAPTER 8—AMPHIBIA
The amphibians consist of three well-defined typesgroupedin three
Orders, Caudata (Salamanders and Newts), Gymnophiona (Caecilians)
and Salientia (Frogs and Toads). These orders havecertain characters in
common. They are cold blooded vertebrateshaving a smooth or rough
glandular skin and lacking fur. feather,and/or scales found in dry-skinned,
truly land vertebrates. A primitivetype of scale occurs embedded in the
skin in some caecilians.
The most remarkable factor in the life of amphibians is their
breedinghabit. It is a well-known fact that, among land vertebrates,
onlyamphibians begin their lives in water as tadpoles, it is during
thebreeding season, coinciding with the monsoons in India, that
thenormally circumspect frogs and toads throw all caution to the windsand
the male makes its presence known by its loud call, a soundwhich, at night
in well-watered country, is a continuous roar asthousands of frogs and
toads of different species give tongue to advertisetheir presence in the
selected breeding site.
The manner of deposition of the eggs varies; many frogs lay themin a
frothy mass. Among the tree frogs the eggs are usually not laidin water,
but in a situation which would enable the developing youngto be released
into water. The egg mass hardens into a crust on theoutside in these
species. The toads Jay their eggs in gelatinous stringsof varying lengths
which are loosely twined round water-weeds by themovements of the
female. The number of eggs laid by one femalemay be as high as 2000 in
Indian species ; those which have an abbreviated larval life lay a smaller
number varying with the period of thelarval life.
Amphibians are relatively defenceless animals and seek safety
increvices and other shelters when faced with danger or remain
immobiledepending on their cryptic coloration to escape detection. The
skinsecretions also give a certain amount of protection, but many
predatorsare immune to their effect.
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