Subphylum Hexapoda Flashcards
The Hexapod’s body is divided into _ tagmata?
3 tagmata:
-5 pairs of head appendages
-3 pairs of legs on thorax
-reduced abdominal appendage
What are the 2 classes of hexapods?
Entognatha
Insecta
What are pteryogotes?
winged insects
What are apteryogotes?
wingless insects
What adaptive traits contributed to insect dominance on land?
-exoskeleton (conserving water)
-evolution of flight/small size
-well protected eggs
-variety of structural/behavioral adaptations
What are some common features of Class Insecta?
-sclerites (
-head (compound eyes)
-thorax (wings)
-abdomen (9-11 segments)
-antennae (touch, taste, hearing)
-legs (large variability)
Another common feature of Class Insecta is mouthparts. What are the functions of:
Labrum
Mandibles
Maxillae
Labium
Hypopharynx
Labrum - upper lip for sensory
Mandibles - sclerotized for chewing
Maxillae - sensory, cutting surfaces, food-holding palps
Labium - lower lip with sensory palps for food holding
Hypopharynx - tongue-like sensory structure
What are the 2 modifications of the mouthparts?
- Sucking mouthparts - some variation in the basic structure
mosquitoes - six stylets from labrum, hypopharynx, mandibles and maxillae used for piercing and sucking
butterflies, moths - maxillae modified into long, coiled tube - Sponging mouthparts -labium expanded into soft labial lobes
flies
What is the hypothesis of the origin of flight?
-Wings may have evolved from gill-like lateral outgrowths of thorax
-Used for gliding and the ability to flap came later
Most insects have two pairs of wings. Describe forewing/hindwing.
-Thin and membranous or Thick and hard
-Covered with scales or hairs
What is Diptera?
True flies
-only has one pair of wings
-with halters
Describe wing movements controlled by muscles in the thorax
locusts and dragonfly
-Indirect flight muscles contract which elevates wings
-Direct flight muscles contract which lowers wings
flies and midges
-longitudinal thoracic muscles contract and arch tergum
Describe the process of synchronous flight
-single nerve impulse stimulates wing muscle contraction
-thus, one wing beat
Describe the process of asynchronous flight
-depends on stored potential energy in tergum and specialized muscle fibers
-wing beats out of phase with nerve impulses
-allows very fast wing beats
What are the different strategies aquatic insects use for gas exchange?
-diffusion across body wall
-bubble of air around spiracles
-tracheal/coxal gills
Ametabolous metamorphosis (direct)
-both adults and larvae are wingless
-number of molts varies and continues after maturity
-body size and sexual maturity differs between adults and larvae
Hemimetabolous metamorphosis
-series of molts from egg to adult stage
-nymphs gradually take on adult form
-nymphs are called naiads if aquatic, usually have gills
Ecdysis
-necessary for increase in size
-old cuticle shed > growth > new cuticle > hardening
-molting animals grow in the intermolt phases or instars
-old cuticle shed by taking in water or air and increased blood pressure
-new cuticle formed prior to molt of old cuticle
Describe intermolt phase or instars
soft tissue increases in size until there is no space within the cuticle
Explain ecdysis and formation of new cuticle under hormonal control
-PTTH produced by neurosecretory cells in brain and ganglia
-Prothoracic gland
-Ecdysone(molting hormone is produced
-Formation of new cuticle and ecdysis
