LYFE CYCLES IN ANIMALS

LYFE CYCLES IN ANIMALS INSECT METAMORPHOSIS

METAMORPHOSIS • Physical changes from one stage in life cycle to another. • TWO TYPES OF METAMORPHOSIS: • 1. Complete metamorphosis • 2. Incomplete metamorphosis

Comparison of metamorphosis 88 % of all insects • COMPLETE • Four stages: • 1. egg • 2. larva • 3. pupa • 4. adult • E.g. Butterflies, bees, housefly

12 % of insects • • • • •

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