UNIT

4 The reproduction function

Natural Science 2. Secondary Education

POST-EMBRYONICDEVELOPMENT

Post-embryonic development

POST-EMBRYONICDEVELOPMENT

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DIRECT INDIRECT

can be

UNIT

4

Natural Science 2. Secondary Education

• The new-born individual is similar to the adult, only smaller.

• Its development consists of:• Growth.• Maturity of the organs.

Direct development

• Boars develop this way.

Post-embryonic developmentUNIT

4

Natural Science 2. Secondary Education

The direct development of the boar

The baby is born with a similar appearance to the adult: the difference is in its size and fur, which has some characteristic lines in the back.

During the first months of its life, the lines disappear and its fur turns a reddish colour.

As it grows, the boar’s fur gets darker becoming brown as an adult.

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Post-embryonic developmentUNIT

4

Natural Science 2. Secondary Education

• In indirect development, the new-born individual, the larva, looks completely different from the adult.

• The transformation from larva to adult takes place through a series of transformations called metamorphosis.

• In metamorphosis, the larva loses some organs and generates others.

Indirect development

• Ladybirds develop this way.

Post-embryonic developmentUNIT

4

Natural Science 2. Secondary Education

The metamorphosis of the ladybird

Fertilisation

After fertilisation the ladybird lays eggs. When the embryo

has completely developed, hatching takes place.

The larvae that are born are very different from the adults.

The larvae form a cocoon where they will complete their metamorphosis.

Once the transformation is complete, an adult individual emerges.

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Post-embryonic developmentUNIT

4

Go back to the Start menuNatural Science 2. Secondary Education