Why are Insects So Successful?

Question 1

What are mouthparts that are hidden inside the head called?

Answer 1

Entognathous

Question 2

Why is the subphylum Hexapoda so successful?

Answer 2

• Widely distributed in all available habitats
• Great number of species - can utilise habitats as they don’t take up as much space as larger animals
• Diverse in shape and size so competition is reduced
• All manners of life strategies shown

Question 3

What is the most diverse group of animals (within arthropoda)?

Answer 3

Hexapoda

Question 4

How many orders are there in hexapoda?

Answer 4

Almost 30

Question 5

How many Hexapoda orders are ‘non-Insecta’, just outside true insects?

Answer 5

3

Question 6

What makes 3 orders within Hexapoda ‘non-Insecta’?

Answer 6

Entognathous mouthparts, lack a clear metamorphosis, reproduce by external fertilisation

Question 7

What are the 3 orders of Hexapoda that are ‘non-Insecta’?

Answer 7

Collembola, Protura, Diplura

Question 8

The earliest insects lacked wings. What are insects that have never had wings classified as?

Answer 8

Primitively wingless

Question 9

What are the two orders of insecta that are primitively wingless?

Answer 9

Zygentoma (silverfish) and Archaeognatha

Question 10

What method of fertilisation do winged insects generally have?

Answer 10

Internal fertilisation, while orders that are just outside ‘true insects’ all have external fertilisation

Question 11

What are tagmata?

Answer 11

The 3 major groups of segments in the arthropod body

Question 12

What are the 3 tagmata of arthropods?

Answer 12

Head, thorax, abdomen

Question 13

How many pairs of legs are on the thorax of arthropods?

Answer 13

3 pairs

Question 14

What do insects and Myriapods use for breathing?

Answer 14

Traceael system - fine tracheoles reach the vicinity of all cells. Air sacs help circulation of air.

Question 15

What do insects use for vision?

Answer 15

A combination of compound eyes and ocelli

Question 16

What are ocelli?

Answer 16

Simple eyes often placed in between compound eyes as horizon detectors

Question 17

What factors make insects so successful?

Answer 17

• Metamorphosis
• Feeding strategies
• Flight
• Social behaviour
• Small size
• Reproductive potential

Question 18

What is metamorphosis?

Answer 18

Sharp change in form between the larval and adult stages

Question 19

How does metamorphosis benefit the success of insects?

Answer 19

Metamorphosis allows insects to exploit different ecological niches at different life stages. Larvae and adults often have distinct feeding habits, diets, and habitats, reducing competition for resources and mates within the same population and maximizing resource utilization within ecosystems.

Question 20

How might reproductive output be increased by insects carrying out metamorphosis?

Answer 20

Often involves a transition from a non-reproductive to a reproductive stage in the insect life cycle (holometabolous insects).
Optimized reproductive output by investing resources in growth and development during the larval stage and reproduction during the adult stage, maximizing the production of offspring over their lifetime.

Question 21

How do the feeding strategies of insects benefit their success?

Answer 21

Can use almost any food sources. High degree of specialization allows more species to utilize the same habitat.

Question 22

What is the name for insects that feed on decaying organic material?

Answer 22

Saproghages

Question 23

What are the different feeding mechanism functional groups for freshwater macro invertebrates?

Answer 23

• Shredders
• Collectors
• Grazers
• Predators
• Piercers
• Parasites

Question 24

How does flight benefit the success of insects?

Answer 24

Predator escape
Can quickly colonise new habitats
Migrate between temporary habitats and utilise seasonal resources

Question 25

What are the two types of flight muscles?

Answer 25

• Direct = attached directly to base of wings
• Indirect = attached to the wall of the thorax

Question 26

How many times has powered flight evolved and in what groups?

Answer 26

4 times
- Insects
- Pterosaurs
- Birds
- Bats

Question 27

What else are wings useful for?

Answer 27

• Startling
• Mimicry
• Camouflage
• Can be useful for wings to have eyespots as this means that predators will aim for parts of the body that are not vital for survival (e.g. peacock butterflies)

Question 28

What two orders are social insects mainly from?

Answer 28

Hymenoptera and Blattodea

Question 29

How does social behaviour contribute to the success of insects?

Answer 29

Division of labour optimizes the efficiency and productivity of a colony.
- foraging, nest construction, defence, brood care, reproduction

Question 30

Give examples of eusocial insects.

Answer 30

Honeybees and Leafcutter ants

Question 31

What are the disadvantages of the small size of insects?

Answer 31

• Rapid heat loss due to small body size ratio
• Temperature regulation has a profound effect on biology
• Warmer weather can accelerate activity and shorten life span
• Moulted exoskeleton is not strong enough to support the soft body

Question 32

Give an example of where small body size is both positive and negative.

Answer 32

Small body size in parasitoid Hymenoptera can favour early reproduction which is beneficial for females that have a limited number of eggs they can produce in their lifetime, but leads to reduced longevity.

Question 33

What are the benefits of the rapid breeding rates of insects?

Answer 33

Fast population growth, cope with alterations in environment, can quickly replenish population numbers if required. Large population sizes and short generation times facilitate the accumulation and spread of beneficial genetic variations to enhance survival in new conditions. Greater plasticity - genetically, behaviourally.