Arthropod III Flashcards
How many times have wings evolved in insects?
Once
How many pairs of wings in adult pterygota?
Two pairs of wings
What are wing pads?
Flattened structures on the bodies of nymphs that form wings in adult insects
What is a nymph?
A sexually immature form which is usually similar to the adult (found in insects such as grasshoppers and cockroaches)
What kind of termite doesn’t have wings?
Workers
Give an example of something that has loss wings
Parasitic lice
What are the two theories for the origin of insect wings?
Paranotal theory
Endite-exite theory
Paranotal theory of insect wing origin
Wings originated from outgrowths of nota
What is the nota (insect anatomy)
Notum is the dorsal portion of an insects thoracic segment
Endite-exite theory of insect wing origin
Wings originated from exites of primitive leg segments
What is an exite (insect anatomy)
X
What is the cycle of powered flight?
Power stroke (down and forward)
Recovery stroke (up and backward)/
What is the leading edge
Edge of the wing towards the front of the insect
Which part of the wing is made of cuticle?
Wing veins made of cuticle to strengthen them
How many times has powered flight appeared in the history of life?
Four times
What order did these lads evolve
Bats
Birds
Pterosaurs
Insects
Insects
Pterosaurs
Birds
Bats
What are direct flight muscles?
Flight muscles attached directly to the wing
Which insects have direct flight muscles?
In the paleoptera
Dragonflies and mayflies
What do antagonistic muscles do?
Contract to give cyclic movement
What do anterior and posterior direct muscles control?
Forward and backward movement
What do elevator muscles do?
Pull the wings up
What do depressor muscles do?
Pull the wings down
Indirect flight muscles
Muscles not directly attached to the wing
Move wings indirectly by changing confirmation of the thorax
Indirect vertical flight muscles
Do the recovery stroke
- pull on roof of thorax
- wings rise
- thorax widens and lengthens (squishes)
- longitudinal muscle stretch
Indirect longitudinal flight muscles
Do the power stroke
- pull on anterior and posterior ends of thorax
- wings lower
- thorax shortens and narrows
Which kind of muscle controls steering?
Direct muscles
Likely evolutionary steps for wing formation
- Gliding
- Evolution of hinge, ve nation, muscle and respiration
- Folding of wings
- Asynchronous muscle
What is asynchronous muscle
muscles in which there is no one-to-one relationship between electrical stimulation and mechanical contraction.
(Contract multiple times from a single nervous impulse)
What are synchronous muscles XX
X
Why did asynchronous muscle evolve?
To increase wing beat frequency
To allow a decrease in body size
Advantages of flight and wings
- Mobility
- Dispersal
- Predator avoidance
What is powered flight a reason for?
Reason for the huge diversity and abundance of insects
Ametaboly
No metamorphosis; the immature form is like a miniature version of the adult
Hemimetaboly
Incomplete metamorphosis
Immature version is a nymph which is miniature version of the adult but wingless
Wings appear in late nymphs after moulting
Holometaboly
Complete metamorphosis
Immature form is very different from adult (larva)
Larva transforms into pupa and winged adult emerges form pupa
What percentages of species are holometaboly?
83%
What are the pterygota?
A subclass of insects that includes winged insects and secondarily wingless insects
In holometaboly what is the adult form known as?
Imago
How is holometabolous development controlled?
Hormonally
Imaginal discs
Sac like epithelial structure which is inside the larvae of insects that are undergoing metamorphosis
What is an important advantage of holometabolous development
Larvae and adults are ecologically different
- so they have specialised niches
- and therefore resource partitioning
- which means less competition between the different life stages (eg. Adult and larvae)
What is diapause
State of arrested development of an insect (can pause depending on environment)
4 advantages of holometabolous development
- Larvae and adults are ecologically different so less competition between different life stages
- Gives mechanism to control the speed of development
- Diapause allows insects to pause development depending on environment
- Allows parasitoidism to occur (larvae form live on host)
Example of what species holometaboly allows parasitoidism to occur in?
Four families of wasps and flies
Ovipositor
Tube like organ used by wasps to lay eggs
Hyperparasitoids
Parasitoids that lay their eggs in other parasitoids
Most important method for controlling insect populations?
Parasitoids
How many Hexapoda to parasitoids?
Thought that every hexapod has its own parasitoid
8 reasons for arthropod success
XXX
- Wings
- Holometabolous development
- Adaptions for terrestrial existence
- Co-evolution with flowering plants
- Eusociality
- Arthropod general body plan and features
- Tagmosis and fusion/loss of body segments
- Specialisation of segmental appendages
How have adaptions for terrestrial existence made insects successful?
- waxy cuticle prevents dessiccation
- trachea and spiracles limit water loss
- ## hyperosmotic excreta mean they use less water than they excrete
How to define arthropod ‘success’
- clade longevity
- abundance (number of individuals)
- diversity (number of species)
- distribution of species
- dominance and impact on ecosystem
