Basic elements of the insect exoskeleton
-Composed of a cuticle that covers the body and is secreted by the epidermis
-protects against dehydration, abrasions, and attack from predators
-mostly chitin with other proteins and waxes
Axes of the insect body
-Longitudinal
-Transverse
-Dorsoventral
Parts of insect head
Head regions (sclerites) separated by sutures
-antenna
-compound eye
Insect mouthparts and their orientation
-Labrum (upper lip)
-Hypopharynx (tongue)
-Mandibles (jaws)
-Maxillae
-Labium (lower lip)
Elements of the insect antenna (proximal to distal)
-Antennal sclerite
-Scape
-Pedicel
-Flagellum
Basic antennal types
-Filiform (threadlike)
-Serrate (saw-toothed)
-Geniculate (elbowed)
-Moniliform (beadlike)
-Pectinate (comb-shaped)
-Plumose (plume-like)
-Capitate (knoblike)
-Flabellate (fan)
-Aristate (bristle-like)
-Lamellate
Insect leg segments (proximal to distal)
-Coxa
-Trochanter
-Femur
-Tibia
-Tarsus
-Pretarsus
Insect leg modifications
-Raptorial (grabbing)
-Saltatorial (jumping)
-Cursorial (running)
-Fossorial (digging)
-Natatorial (swimming)
Hydrostatic Exoskeleton
Soft-bodied adults/larvae maintain turgidity by criss-crossed body wall "turgor" muscles that continuously press against the incompressible hemolymph of the hemocoel - foundation for other muscles
What is the tripod of legs?
Continuous contact with the ground - fore/hind legs on one side move with middle leg on the opposite side
What type of muscles do insects have? How are they attached to the exoskeleton?
-Striated muscle consists of overlapping layers of protein molecule
-Via tonofibrillae link to epidermis
Compare direct and indirect flight muscles. How does each type move the insect wing?
Direct: muscle attached directly to wings
Indirect: no muscle-wing connection; muscle action deforms throax by moving notum up/down to move wings
The basic elements of the central nervous system
Series of ganglia joined by paired longitudinal nerve cords lying ventrally in body cavity
The two ganglionic centers of the insect head and the function of each
Brain: associated with vision, innervates antennae handles signals from body
Subesophogeal Ganglion: innervates mouthparts
The four insect endocrine centers and their functions
Neurosecretory Cells - modified neurons found throughout the nervous system
Corpus Cardiacum - pair of neuroglandular bodies located on either side of aorta; stores/release neurohormones
Prothoracic Glands - secrete ecdysone (elicits molting)
Corpus Allat
Functions of important insect hormones
Ecdysteroids - steroids that promote molting
Juvenile hormones - control metamorphosis and reproductive development
Neurohormones - protein messengers regulating development, homeostasis, metabolism, and reproduction
Basic elements of the open circulatory system in insects
Dorsal vessel
-anterior dorsal vessel
-posterior dorsal vessel
-ostia dorsal vessel
Basic elements of the insects respiratory system
Gas exchange
Trachea - air enters trachea vis spiracles
Maximum of 10 pairs
+2 thoracic
+8 abdominal
Closed vs. Open tracheal systems
Open: valved spiracles open directly to environment
Closed: no spiracles, closed to environment; gas exchange occurs directly through cuticle
i.e. open (cockroach) closed (dragonfly naiad)
Three basic regions of the alimentary canal
Foregut, midgut, hindgut
Function of malpighian tubules
Primary organs of excretion & osmoregulation; act in concert with rectum and/or ileum
Primary structures of the female and male reproductive systems
Male: paired testes, paired vas deferentia, seminal vesicles, median ejaculatory duct, accessory glands, genitalia
Female: paired ovaries, paired oviducts, egg calces, common vagina, spermatheca, ovipositor
organ in the females (spermatheca) fertilization
Major contributions of John Ray and Carolus Linnaeus
John Ray: classified plants according to similarities and differences that emerged from observation - first to coin the term "species"
Carolus Linnaeus: grouped genera by shared similarities, introduced concept of binomial nomenclature
Year that marks beginning of zoological nomenclature
1758
Five reasons for classifying organisms
1. Communicate, store, and retrieve information
2. Create informed hypothesis
3. Understand shared evolutionary history of species
4. Help solve environmental and human welfare challenges
Eight basic taxa of zoological classification (large->small)
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Define: Biological species concept
Species as members of populations that actually or potentially interbreed in nature
Basic elements of cladistics
Seeks to determine the relationships among a group of organisms (taxa) based on their evolutionary novel characteristics
Closest living relative of insects
Crustaceans
List two synapomorphies of hexapods
Three functional body regions, three segmented thorax, one pair of antennae
Most basic diagnostic feature that distinguishes Entognatha from Insecta
Basis of mouthparts hidden within head capsule