LYFE CYCLES IN ANIMALS

INSECT METAMORPHOSIS

• Physical changes from one stage in life cycle to another.

• TWO TYPES OF METAMORPHOSIS:

• 1. Complete metamorphosis

• 2. Incomplete metamorphosis

METAMORPHOSIS

Comparison of metamorphosis

88 % of all insects 12 % of insects• COMPLETE • Four stages:• 1. egg• 2. larva• 3. pupa• 4. adult

• E.g. Butterflies, bees, housefly

• INCOMPLETE• Three stages:• 1. egg• 2. nymph• 3. adult

• E.g. Locust, cricket, cockroach

Complete metamorphosis

Incomplete metamorphosis

Advantages and disadvantages of complete metamorphosis

• Advantages:1. Larva and adult occupy

different habitats and niches – not in competition.

2. Carrying capacity of ecosystem increased.

3. Egg and pupa stages allow insect to survive unfavourable conditions.

• Disadvantages:1. Larval forms vulnerable to

predators.2. Suitable habitat for laying of

eggs needed.3. Change from pupa to adult

requires high energy-input.

Advantages and disadvantages of incomplete metamorphosis

• Advantages:1. Vulnerable pupa stage

avoided.2. Less energy is needed – no

drastic changes from pupa to adult.

3. All stages can eat same food.

• Disadvantages:1. Nymph and adult often

compete for same food.2. Insect vulnerable to

dehydration and predators when moulting.

3. Entire insect population could be threatened by environmental changes.

Amphibian metamorphosis