Frogs Of Tropical Africa
Everyone must know this animal,
which belongs to a family called the "Amphibians", a word which means "animals that
live both on land and in water. The frog passes the earlier part of its life entirely
in water, but later lives on the land. True, it is generally to be found in moist
places, but at times it stays in quite dry spots, and then appears mostly during
the rains. The frog's body possesses no scaly, feathery or hairy covering; the skin
is quite bare and in this way Amphibians are different from mammals, bird, or reptiles.
The frog feeds on slugs and insets. The insects it catches with its tongue, which
can be shot out for several inches, and which is covered with a viscid (sticky)
substance. Once in the mouth the insect is prevented from escaping by the teeth
and is swallowed whole. The frog has two sets of teeth, one on the jaw and the other
in two small patches on the roof of the mouth. A curious thing about frogs is that
although in the ordinary way they breathe through their nostrils, yet in very cold
or dry weather they can lie buried in the ground for months on end, during which
time they breathe through their skin; they also do this when they are detained under
water for a long dine.
of hair like
the dog, or fur like the cat; others like the frog have no coat at all, while fishes
have scales.
The life history of the frog is very interesting. It commences life as an egg in
a mass of some thousands all joined together, but each with a round body of white
watery jelly-like substance round it. This "jelly" is very distasteful to fish,
birds, and other enemies which would otherwise eat the eggs, and thus the eggs are
protected. Frog's eggs have no definite shell like those of birds or reptiles, but
have merely a clear soft skin. The eggs are laid in water, and after about a fortnight
they hatch out, and the larva escapes. This larva attaches itself to pieces of grass,
water-weeds, stones, etc. At this stage it looks like a small black worm about half
an inch long. Gradually a definite head and tail appear, and the larva grows much
more active, and eventually becomes what is called a "tadpole". Later, the tadpole
develops legs; first the hind legs appear and then the fore legs; after that the
tail disappears gradually and the tadpole becomes the adult frog. Tadpoles breathe
by means of gills; when they are very young the gills are seen quite easily, but
later on they are hidden. As the tadpole develops into a frog the gills are lost
altogether, lung: are formed, and the frog is now a land animal. Frogs protect themselves
from their enemies by the way in which they can dive, swim, and remain hidden at
the bottom of water for a long time, and also by the fact that in their skins there
is a very sour juice that animals do not like. Other frogs, in addition to this,
can squirt out a burning fluid when attacked or frightened, and this helps considerably
to protect them from their enemies. Frogs are useful to man. The larva and tadpoles
feed mainly on water-weeds, but frog: themselves on harmful insects, slugs, etc.
They are thus of great use in the garden. So much good indeed do they do that in
some countries they are protected by law and encouraged to breed, for the purpose
of destroying beetles, snails, wire-worms, weevils, white ants. In some parts of
the world certain frogs are eaten.