Issue 12 Arthropoda

Yukino Watanabe L6th

Metamorphosis

reveals the secret of how

insects undergo

‘change’

‘shape’

metamorphosis

M

food sources as it is essential that

whereas JHs ensure the growth

etamorphosis is

they store energy for later stages.

of the larvae and prevent

where an animal

Larvae have voracious appetites

metamorphosis.The role of JH is

physically

and eat several times their own

to delay metamorphosis (keeping

transforms from a larva into an

body weight each day. Later, the

them juvenile) until the larva has

adult with abrupt changes in its

insect develops a shell, turning

reached an appropriate size.A

body structure. Many insects

into a pupa. At this phase, it stops

drop in JH triggers

undergo metamorphosis including

moving or eating. An astonishing

metamorphosis in insects.

butterflies, bees, ants, beetles, and

transformation takes place; the

Metamorphosis often means that

mosquitos.

insect’s structure completely

adult insects exist in a completely

Insects can undergo incomplete

changes, then an adult form

different habitat to the larvae.

metamorphosis, with a nymph

hatches out.

This means that there won’t be

stage, which is just a smaller

How metamorphosis occurs

competition for food between

version of the adult that gets

differs by species but it is

larvae and adults, and it allows

larger and larger with each moult.

controlled by hormones.The two

the larvae to exploit food

These insects do not show

most important hormones for

resources in the original habitat

distinct changes in form.

metamorphosis in butterflies are

and still be able to move away to

Insects that do complete

ecdysteroids (ECDs), which are

a new habitat when it has fully

metamorphosis undergo four

similar to testosterone, and

grown. Living in a new

stages: egg, larva, pupa, and adult.

juvenile hormones (JHs). ECDs

environment with different

Complete metamorphosis begins

causes changes in gene

selection pressures enhances the

when the insect hatches out from

expression

potential for adaptation and

its egg into the worm-like larva.

evolution.

Larvae have well-developed

It is with the benefits of

organs for movement because a

metamorphosis that insects are

larva has to look for

the most diverse and successful

group in the animal kingdom ∎

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