Insect 2 Flashcards
Do insects internally or externally fertilise?
Internal
What is remipedia?
Sister group to the hexapoda
Possibly could be the intermediate form from crustaceans to the hexapoda
What is synapomorphy?
Character shared by all the descendent species - strong evidence of relatedeness
What are some synapomorphies of the Hexapoda?
Tagmosis pattern - 6 segment head, 3 segmented thorax and 11 segmenated abdomen
Reduction in leg sements (fusion of patella and tibia)
Two primary pigment cells of the ommatidia
9+9+2 pattern of microtubules in sperm flagellum
What makes up the entognatha?
Collembola (springtails), diplura (bristletails) and protura
Give some features of the entognatha
Entognathy (mouthparts are enclosed by folds)
Less developed malpighian tubules
Reduced or absent compound eyes
Elongate sac like ovarioles
Almost all have eversible vesicles of some kind
Give some features of the orders that make up the Entognatha
All from the basal insect lineages
Order Collembola:
-compound eyes
-prominant antennae
-still wingless
-furculum
Order Protura:
-antennae absent
-eyes absent
-elongated body
Order Diplura:
-simple ocelli
-antennae present
-still wingless
-two prominant cerci
What are eversible vesicular tubes for?
Electrolyte balance
Water uptake
Adhering to surfaces
Self-righting after vigirous jumping
What were the 3 key innovations after the basal insect lineages?
Evolution of wings
Evolution of wing-folding mechanisms
Holometabolism
What is the pleural hypothesis of wing evolution?
Gills gave rise to wings
Surface skimming as an intermediate function before evolving flight
What is the paranotal hypothesis of wing formation?
Thorax outgrowths gave rise to wings
What functions could cause rapid directional selection of wings?
Courtship
Thermoregulation
Aerodynamics
Respiration
What is the dual-origin hypothesis for wing development?
Wings are derived from selective regulation of HOX genes in tissue from the thorax and the pleural zones
How does the insect pterothorax work?
Wing is attached to notal hinge
When the dorso-ventral muscles contract, the abdomen squishes
The longtiduinal muscles relax
The wings then pop out
Vice versa
What are the paleoptera?
Basal lineages that are unable to fold wings back over the body
Have no olfactory bulb in the brain
Include the ephemeroptera (mayflies) and the odonata (dragonflies + damselflies)
Give some features of the order ephemeroptera (mayflies)
2500 species
Aquatic with elaborate abdominal gills
Reduced hindwings but large forewings
Long cerci
Emergence is tightly synchronised with the environment
Give some features of the order Odonata (dragonflies + damselflies)
Large compound eyes (eat small tadpoles as nymphs)
Internal fertilisation
Modifies jaws of larvae
Rectal gills - have a dense tracheole system that can draw in water muscularly
Caudal gills
Jet propulsion
Males have an aedeagus - for depositing sperm and extracting sperm from a prior male
Give some features of a compound eye
Made of ommatidia
No optic nerve - signal runs directly to the brain
Cuticular lens allows light through
Cone focusing structure
Retinula cells stimulates by light - light is govered by pigment cells
