Sunday, 18 November 2012

2.2 The Life Processes Of Animals

All animals can reproduce and have young of offspring. Based
on their way of reproduction, we can divide animals into two groups.

A)Animals that give birth

Animals such as lions, cows, whales and
dolphins give birth to their young. The young grow in their mother’s womb until
they are born. After birth the young feed on their mother’s milk.

B)Animals that lay eggs

Animals such as birds , frogs, crocodile
and grasshoppers lay eggs.their young hatch from the eggs
after few days or weeks

Animals
go through different stages in their life.The life cycle of an animal
shows how the young of an
animal develop into an adult that is capable of
producing young.

The egg is a tiny, round, oval, or cylindrical object,
usually with fine ribs and other microscopic structures. The female attaches
the egg to leaves, stems, or other objects, usually on or near the intended
caterpillar food.

The caterpillar (or larva) is the long, worm-like stage of
the butterfly or moth. It often has an interesting pattern of stripes or
patches, and it may have spine-like hairs. It is the feeding and growth
stage. As it grows, it sheds its skin four or more times so as to enclose its
rapidly growing body.

The chrysalis (or pupa) is the transformation stage within
which the caterpillar tissues are broken down and the adult insect's
structures are formed. The chrysalis of most species is brown or green and
blends into the background. Many species overwinter in this stage.

The adult (or imago) is colorful butterfly or moth usually
seen. It is the reproductive and mobile stage for the species. The adults
undergo courtship, mating, and egg-laying. The adult butterfly or moth is
also the stage that migrates or colonizes new habitats. The butterfly
pictured here is a Monarch, which is fairly large in size. The
Monarch's wingspan is 3 3/8 - 4 7/8 inches (8.6 - 12.4 cm).

Egg

Frogs and Toads tend to lay many eggs because there are
many hazards between fertilization and full grown frogness! Those eggs that die
tend to turn white or opaque. The lucky ones that actually manage to hatch
still start out on a journey of many perils.Life starts right as the central yolk splits in two. It then divides into four,
then eight, etc.- until it looks a bit like a raspberry inside a jello cup.
Soon, the embryo starts to look more and more like a tadpole, getting longer
and moving about in it's egg.

Usually, about 6-21 days (average!) after being fertilized,
the egg will hatch. Most eggs are found in calm or static waters, to prevent
getting too rumbled about in infancy!. Some frogs, like the Coast foam-nest
tree frog, actually mate in tree branches overlooking static bonds and streams.
Their egg masses form large cocoon-like foamy masses. The foam sometimes cakes
dry in the sun, protecting the inside moisture. When the rain comes along,
after development of 7 to 9 days, the foam drips down, dropping tiny tadpoles
into the river or pond below.

Tadpole

Shortly after hatching, the tadpole still feeds on the remaining
yolk, which is actually in its gut! The tadpole at this point consists of
poorly developed gills, a mouth, and a tail. It's really fragile at this point.
They usually will stick themselves to floating weeds or grasses in the water
using little sticky organs between its' mouth and belly area. Then, 7 to 10
days after the tadpole has hatched, it will begin to swim around and feed on
algae.

After about 4 weeks, the gills start getting grown over by
skin, until theyeventually disappear. The tadpoles get teeny tiny teeth which help them
grate food turning it into soupy oxygenated particles. They have long coiled
guts that help them digest as much nutrients from their meadger diets as
possible.By the fourth week, tadpoles can actually be fairly social creatures. Some eveninteract andschool like
fish!

Tadpole
with legs

After about 6 to 9 weeks, little tiny legs start to sprout. The head
becomes more distinct and the body elongates. By now the diet may grow to
include larger items like dead insects and even plants.
The arms will begin to bulge where they will eventually pop out, elbow first.
After about 9 weeks, the tadpole looks more like a teeny frog with a really
long tail. It is now well on its way to being almost full-grown!

Young
Frog, or Frog let

By 12 weeks, the tadpole has only a teeny tail stub and looks like a
miniature version of the adult frog. Soon, it will leave the water, only to
return again to lay more eggs and start the process all over again!

Frog

By between 12 to 16 weeks, depending on water and food
supply, the frog has completed the full growth cycle. Some frogs that live in
higher altitudes or in colder places might take a whole winter to go through the
tadpole stage...others may have unique development stages that vary from your
"traditional" tadpole-in-the-water type life cycle: some of these are
described later in this tour. Now these frogs will start the whole process again...finding mates and creating
new froggies.

Eggs: A hen lays eggs in a nest. Some eggs have an embryo
inside. An embryo will grow into a chick in 21 days. The mother hen
must keep the egg warm. The egg's hard shell protects it while it
grows. The baby bird will use an egg tooth on it's beak to hatch out of
the egg. This can take a full day!

Chick: The chick is wet when it hatches from its egg. It
has feathers called down. The down will dry fast. Also, chicks can
walk right away. They like to eat seeds, bugs, and worms. Chicks
grow more feathers in about 4 weeks. A comb grows on the chick's head and a
wattle grows under the chick's beak. Chicks resemble their parents from
the time they hatch and as they grow.

Chicken: Chicks are fully grown into chickens in six
months. Female chicks grow up to be hens. Male chicks grow up to be
roosters. The hens will lay more eggs.