Why are Insects So Successful? Flashcards
What are mouthparts that are hidden inside the head called?
Entognathous
Why is the subphylum Hexapoda so successful?
- 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
What is the most diverse group of animals (within arthropoda)?
Hexapoda
How many orders are there in hexapoda?
Almost 30
How many Hexapoda orders are ‘non-Insecta’, just outside true insects?
3
What makes 3 orders within Hexapoda ‘non-Insecta’?
Entognathous mouthparts, lack a clear metamorphosis, reproduce by external fertilisation
What are the 3 orders of Hexapoda that are ‘non-Insecta’?
Collembola, Protura, Diplura
The earliest insects lacked wings. What are insects that have never had wings classified as?
Primitively wingless
What are the two orders of insecta that are primitively wingless?
Zygentoma (silverfish) and Archaeognatha
What method of fertilisation do winged insects generally have?
Internal fertilisation, while orders that are just outside ‘true insects’ all have external fertilisation
What are tagmata?
The 3 major groups of segments in the arthropod body
What are the 3 tagmata of arthropods?
Head, thorax, abdomen
How many pairs of legs are on the thorax of arthropods?
3 pairs
What do insects and Myriapods use for breathing?
Traceael system - fine tracheoles reach the vicinity of all cells. Air sacs help circulation of air.
What do insects use for vision?
A combination of compound eyes and ocelli
What are ocelli?
Simple eyes often placed in between compound eyes as horizon detectors
What factors make insects so successful?
- Metamorphosis
- Feeding strategies
- Flight
- Social behaviour
- Small size
- Reproductive potential
What is metamorphosis?
Sharp change in form between the larval and adult stages
How does metamorphosis benefit the success of insects?
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.
How might reproductive output be increased by insects carrying out metamorphosis?
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.
How do the feeding strategies of insects benefit their success?
Can use almost any food sources. High degree of specialization allows more species to utilize the same habitat.
What is the name for insects that feed on decaying organic material?
Saproghages
What are the different feeding mechanism functional groups for freshwater macro invertebrates?
- Shredders
- Collectors
- Grazers
- Predators
- Piercers
- Parasites
How does flight benefit the success of insects?
Predator escape
Can quickly colonise new habitats
Migrate between temporary habitats and utilise seasonal resources
What are the two types of flight muscles?
- Direct = attached directly to base of wings
- Indirect = attached to the wall of the thorax
How many times has powered flight evolved and in what groups?
4 times
- Insects
- Pterosaurs
- Birds
- Bats
What else are wings useful for?
- 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)
What two orders are social insects mainly from?
Hymenoptera and Blattodea
How does social behaviour contribute to the success of insects?
Division of labour optimizes the efficiency and productivity of a colony.
- foraging, nest construction, defence, brood care, reproduction
Give examples of eusocial insects.
Honeybees and Leafcutter ants
What are the disadvantages of the small size of insects?
- 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
Give an example of where small body size is both positive and negative.
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.
What are the benefits of the rapid breeding rates of insects?
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.
