Download Phylum Arthropoda Subphylum Hexapoda

•6 legs
•Uniramous legs
•3 tagmata – head, thorax, abdomen
•Appendages
•Appendages on head & thorax
•Abdominal appendages greatly
reduced or absent
 Class Entognatha
 Bases of mouthparts enclosed within head capsule
 Ametabolous
 Lack wings
 Order Collembola
 Order Diplura
 Order Protura
 Class Insecta
 Bases of mouthparts visible outside the head capsule
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Blattodea
Coleoptera
Dermaptera
Diptera
Embiddina
Ephemeroptera
Hemiptera
Hymenoptera
Isoptera
Lepidoptera
Mantodea
Mantophasmatodea
 Neuroptera
 Odonata
 Orthoptera
 Siphonaptera
 > 1 million insect species
 Entomology- study of insects
 Habitat
 Mainly terrestrial: soils, forest, plants, deserts,
wastelands, mountaintops, other organisms
 Fresh water
 Few marine: Brackish water, salt marshes, sandy
beaches
 Wide Distribution due to flight and high adaptability
 Adaptability can be seen in wide diversity
 Adaptability
 Cuticular exoskeleton
 Epicuticle has waxy and varnish layer to close spiracles
 Extract maximal fluid from food and fecal matireals
 Retain water produced in cellular respiration (oxidative
metabolism)
 Diapause- resting stage when insects may lie dormant
during inhospitable conditions
 Tagmata: head, thorax, abdomen
 Cuticle composed of:
 Sclerites (4 plates)
 Dorsal Tergum
 Ventral Sternum
 Pair of lateral pleura (abdominal pleura membraneous)
Tergum
Sternum
Ovipositor
 Thorax
 Prothorax
 Pair of legs
 Tagmata: head, thorax,
abdomen
 Head
 Pair compound eyes,
pair of antennae, 3 ocelli
 Moutparts: labrum, pair
o mandibles, pair o
maxillae, labium,
tonguelike hypopharynx
 Mesothorax
 Pair of legs
 Pair of wings (in most)
 Metathorax
 Pair of legs
 Pair of wings (in most)
 Legs modified for special purposes
 Terrestrial: walking legs with terminal pads and claws
 Pads may be sticky (why?)
 Grasshopper hindlegs: adapted for jumping
 Mole crickets: first pair of legs for burrowing
 Aquatic: paddle-shaped appendages
for swimming (i.e. waterbugs)
 Mantis forelegs: long and
strong for grasping prey
 Double membrane with veins of thicker cuticle
 What do you think the purpose of these veins are?
 Are insect wings homologous or analogous to bird and
flying mammal wings?
 Most have two pairs
 flies only have one pair, second pair
being halteres
 Halteres- balancers
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 Flies: thin & membraneous
 Beetle forewings: thick & stiff
 Grasshopper forewings: partchment-like
 Butterflies/moths: covered in fine scales
 Caddisflies: covered with hairs
 Digestive System
 Circulatory System
 Respiratory System
 Excretory System
 Nervous System
 Reproductive System
 Foregut- lined with cuticle
 Mouth with salivary glands
 Esophagus
 Crop for storage
 Proventriculus for grinding
 Midgut
 Stomach
 Gastric ceca
 Hindgut- lined with cuticle
 Intestines
 Rectum
 Anus
 Phytophagous- feeding on plant juices/tissues
 Some can eat any plant, some are plant-specific
 Some ants/termites cultivate fungus gardens
 Mutualistic symbiotic relationship (how is this so?)
 Saprophagous – feeding on dead animals
 Many beetles & larvae
 Predaceous- feeding on other insects & animals
 Parasitism
 Fleas- scavengers as larvae, parasites as adults
 Lice- parasitic throughout life cycle
 Hyperparasitism……parisitoid
 Wasp larvae
 Feeding habits determined by highly specialized
mouthparts
 Biting/chewing mouthparts
 Mandibles strong with toothed plates to
bite/tear food while maxillae holds food to
mouth
 Enzymes secreted by salivary glands add chemical action ot
the chewing parts
 Sucking mouthparts
 House flies & fruit flies- no mandibles; labium = 2 soft
lobes with small tubules for capillary action
 Horse flies- slender, tapering mandibles to bit and then
to suck blood
 Mosquitos- piercing with stylets and sucking through
food channel
 Honey bees- labium= flexible/contractile “tongue”
covered with many hairs for capillary action and
pumping pharynx
 Butterflies/moths- no mandibles; maxillae = proboscis
 Proboscis coiled while not feeding; extends during feeding
while pharyngeal muscles pump fluid
 Tubular heart in
pericardial cavity
 Dorsal aorta
 Hemolymph (blood)
 Accessory pulsatory organs move blood to legs/wings
 Body movements move blood
 Consists of plasma and amebocytes
 Function: distribute substances throughout body (i.e.
molting hormones and nutrients)
 Tracheal system- tubes that pipe oxygen directly to each
cell
 Function: rapid oxygen-carbon dioxie exchange and
restrict water loss
 Abdominal muscles provide pumping action that draws
air in/out
 Spiracles
 Paired in thorax; 7/8 pairs in abdomen
 Primitive hole in integument or with valve/closing
mechanism
 Why would this mechanism be a good adaptation?
 Tracheae
 Lined with cuticle, shed during
molts
 Taenidia
 Spiral thickenings of the cuticle
 Support tracheae & prevent
collapse
 Tracheoles
 Not lined with cuticle
 Fine, fluid-filled tubules that
tracheae branch into
 Very small insects
 Gas exchange through
diffusion along
concentration gradient
 Water insects
 i.e. nymphs, larvae, adults
 Gas exchange through diffusion through body wall into
and out of tracheal network just under integument
 Aquatic nymphs of stoneflies & mayflies- tracheal gillsthin extensions of body wall containing rich tracheal
supply
 Dragonfly nymphs- rectal gills- ridges in the rectum
where gas exchange occurs as water enters/leaves
 Malpighian tubules- excretory organs & body fluid
conservation
 Environment dependent
 Arid dwelling insects
 Reabsorb nearly all water from rectum = nearly dry mixture
of urine & feces
 Leaf-feeding insects
 Take in & excrete large amounts of water
 Freshwater larvae
 Need to excrete water and conserve salts
 Dry grain-feeding insects
 Conserve water and excrete salts
 Brain = fusion of ganglia
 Some insects have giant fiber system
 Visceral nervous system (similar to autonomic nervous
system of vertebrates)
 Various sense organs
 Sense organs detect mechanical, auditory, chemical,
visual, and other stimuli
 Can sense temperature, humidity, body position
(proprioception), gravity, etc…
 All over body, especially on appendages
 Visual = photoreceptors
 Ocelli = located on head
 Dermal light receptors = located on body
 Compound eyes = large and composed of ommatidia
 Flicker-fusion tests
 Auditory
 Sensilla = sensitive hair-like structures that can detect
sounds
 Modification of cuticular surface for sensory stimuli
reception with one or more neurons
 Tympanis organs = structures sensitive to
sonic/ultrasonic sound
 Sensory cells attached to thin tympanic membrane that
encloses air space in which vibrations can be detected
 Chemoreceptive sensilla
 Found on antennae, mouthparts, and legs
 Mechanical stimuli
 i.e. contact pressure, vibrations, tension changes in
cuticle
 Detected by sensilla or sensory cells in the epidermis
 Neurosecretory cells located in brain have endocrine
function that plays a role in molting and
metamorphosis
 Pheremones = chemicals used to attract a mate
 Dioecious
 Can attract mate through pheromones (even those
several miles away), flashes of light, sound signals, color
signals, courtship behavior
 Usually internal fertilization
 Sperm deposited into female at time of copulation
 Spermatophores being transferred to female
 Sperm can be stored in seminal receptacle for later
fertilization
 # of eggs
 Queen honey bee may lay >1 million eggs in a lifetime
 Some flies = ovoviviparous = one offspring at a time
 Insects with short life cycles and no offspring care = lots
o’ eggs
 Eggs laid in particular habitat to which they are cued
to by visual, chemical, or other clues
 Random facts o’ interest
 Butterflies/moths lay eggs on type of plant caterpillar
feed on
 Tiger moth = pigweed
 Sphinx moth = tomato plant
 Monarch butterfly = milkweed
 Terrestrial insects w/ aquatic immature instars lay eggs
in water
 Braconid wasp lay eggs in sphinx moth caterpillar
where offspring will feed and pupate in white cocoons
 Ichneumon wasps deposits eggs in larva for her
offspring to be parasites
 Uses long ovipositors to penetrate wood to find larva of
wood wasp or wood-boring beetle
 Beneficial insects
 Harmful insects
 Control of insects