The Earth’s largest phylum is Arthropoda, including centipedes, mill
The Earth’s largest phylum is Arthropoda, including
centipedes, millipedes, crustaceans, and insects. The
insects have shown to be a particularly successful class
within the phylum. What biological characteristics have
contributed to the success of insects? In many science
fiction scenarios, post-apocalyptic Earth is mainly
populated with giant insects. Why don’t we see giant
Your assignment should be 250-500 words in length.
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Biological characteristics for success of insects: There are many characteristic features which help in the
success of insects they are Presence of exoskeleton the outer protective covering
layer of body, their small body size, flying capacity, high
reproductive ability, metamorphosis all these helps them
being a successful species.
Exoskeleton – It is a hard structure ,which gives shape and
support to the body\’s soft tissues, gives protection from
predators attack or injury, minimizes the loss of body
fluids in dry and freshwater environments, and gives
mechanical advantage to muscles for strength and ability
to move quickly and freely, It can also resist both physical
and chemical attack. It is covered by an impermeable layer
of wax which prevents desiccation.
Exoskeleton is made up of chitin, a polysaccharide which
binds with various protein molecules to form the body
wall, which is flexible and elastic and hard in nature.
Muscles are attached directly to the body wall which gives
it maximum strength, so that it can lift weight larger than
its body weight.
Small size – small size in presence of exoskeleton helps the
organism, if they were of larger size, exoskeleton might be
larger in size and which, would have added load to the
body and made it difficult for the organism to carry. Small
size also requires minimum resources for survival and
reproduction, helps in escaping and hiding from predators.
Small size and adoption of body shape and color helps in
blending the organism with the environmen t and helps in
escaping the predator.
Insects are the only invertebrates who can fly, this helps
them in migrating from one place to another in case of
necessity. Their body shape also help them to carry a load
15 times more than their body weight.
Reproductive success is another factor for their success, a
female produces large number of eggs and around all of
them usually hatch, there short life cycle also helps in
their success, as a result they produce large number of
offspring. High reproductive potent ial gives the species a
good chance of survival. There are many adaptations to
increase their reproductive potential. They are in many
females, they can store sperm for a longer period almost a
year, inside the spermatheca, a specific part of the
reproductive system. Also in some in a single mating a
female gets enough sperm to fertilize all its eggs.
Unbalanced sex ratios is also another factor, where
females are more than males, it helps in maximizing the
reproductive potential. As most insects are not
monogamous, a few males can supply sperm to a large
number of females. There are many species like aphids,
scale insects, midges in which males are absent, all
members of these species are females, in them the
reproduction takes place asexually.
Metamorphosis is also another factor for their success, it is
the developmental change between immature stage to
adult stage. Metamorphic changes are changes in physical,
biochemical, and behavioural level, they help in the
survival, dispersal, and reproduction of the organism.
At present significant level of pesticide resistance is also
seen in insects which is another mode of adaptation.
All these biological characteristics make it a successful
Huge insects which were found in million years ago, are
now extinct because of these factors 1) Change in atmosphere, million years ago, the air
surrounding earth was warmer, moist and has more
oxygen, as for insects oxygen levels in air is very
important because they don’t possess lungs, there
respiration takes place by spiracles. These a series of
opening along their body through which air flows they
directly connected to the tissues which requires oxygen.
Due to reduction of oxygen level respiration got inhibited
and led to extinction.
2) Evolvement of dinosaurs – When the ancient dinosaurs
evolve, they were flying it put impact on these insects,
they became the predators of these insects and created
competition which led to the extinction of these giant
insects and gradually small sized insects developed.
These are the reasons behind extinction of these giant