Download Arthropods/Insects File

Amazing Arthropods!
The Little Creatures Who Rule the
World
General Characteristics
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Segmented bodies
Jointed appendages
Exoskeleton
Highly cephalized
Open circulatory
system
Exoskeleton - advantages
• Enables great strength
(internal muscle
attachment).
• Waterproof - enables
life on land.
• Protective armor.
Exoskeleton - limitations
• Must be molted (shed)
in order to grow.
Recently molted
animals are
vulnerable.
• http://www.youtube.co
m/watch?v=mF6NgM
BcNCM
• Heavy - limits overall
size.
Cephalization
• Specialized mouthparts sensory, food-handling.
• Antennae - sense
chemicals, vibrations.
• Compound eyes - many
individual units, each
w/own lens, good at
detecting motion, color.
• Simple eyes - detect light
intensity.
Arthropods: Class Crustacea
• Crabs, lobster,
shrimp, barnacles, etc.
• Mostly aquatic
• Two body divisions,
cephalothorax &
abdomen
• http://www.youtube.c
om/watch?v=nmfYW
7wAbQM
• Most crustaceans are
scavengers or
predators.
• Chelipeds – strong
claws for grasping &
cutting or tearing
• http://www.youtube.com/watch?v=b
Sd_5R04f9Q
• http://www.youtube.com/watch?v=m
VuMousxF70
• 4 prs. Walking legs
• Swimmerets – on
abdomen, move water
over gills & or eggs.
Crayfish
Anatomy
Internal Anatomy & Senses
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Green glands – excretory organs in head
Open circulatory system
Gills – attached to each walking leg, moves H2O over them as it walks.
Ventral nerve cord
Compound eyes – many lenses working together, good for detecting
movement.
• Statocysts – detect orientation (up & down) as gravity pulls on grains of
calcium carbonate inside.
• Males have specialized swimmerets for sperm transfer – internal
fertilization.
• Antennae –
touch,
chemicals
Arthropods: Class Arachnida
• Spiders, scorpions,
mites, ticks
• Mostly terrestrial
• Two body divisions,
cephalothorax &
abdomen
• 4 prs. Walking legs
• Carnivorous or
parasitic
Spider
Anatomy
• Book lungs for respiration – large surface area.
• Spinnerets – silk glands produce silk as liquid, emerges
from spinnerets & solidifies on contact with air.
• Spider silk is strongest natural substance known.
• Malpighian tubules – excretory organs, extensions of gut.
• Chelicerae house fangs to inject venom.
• Stronger than steel
• Many uses – webs,
parachutes, guidelines,
camouflage
• http://www.youtube.com/watch?v=y
SXCdcnKBgg
• http://www.youtube.com/watch?v=i
BjjNaRzdEk&NR=1&feature=fvwp
Spider Webs
& Silk
• Millipedes
• 2 prs. legs/body
segment
• Herbivorous
Arthropods:
Class Diplopoda
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Centipedes
1 pr. Legs/segment
Carnivorous
Venomous
Arthropods:
Class Chilopoda
Arthropods:
Class Insecta
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General Characteristics
3 body divisions - head,
thorax, abdomen.
1 pr. antennae
3 prs. Legs on thorax, 1
pr./segment.
2 pr. wings (usually), 1
pr./1st two thoracic
segments.
Insect Adaptations for Success
Flight
Easier to:
• disperse to new
areas.
• find food.
• find mates.
• escape
predators.
Insect Adaptations for Success
Small Size
• Individuals need
fewer resources.
• Many
individuals can
inhabit small
area without
competition.
• Easier to hide.
Insect Adaptations for Success
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Exoskeleton
Great muscular
leverage.
Waterproof.
Protective.
Flexible at joints.
Insect Adaptations for Success
Highly adaptable
• short lifespan &
generation time,
many offspring.
• Frequent mutations,
some beneficial, so
species can respond
to environmental
changes.
Insect Digestive System
Specialized Mouthparts
• chewing – beetle,
grasshopper
• piercing/sucking –
mosquito, true bugs
• sponging - house fly
• siphoning - butterfly
Insect Digestive/Excretory System
• Crop - storage
• Gizzard - grinds food
• midgut (stomach) digestion.
• Gastric cecae - digestive
glands.
• Hindgut - nutrient
absorption
• Malpighian tubules removes waste from
blood, deposits in rectum.
• Open
• Dorsal aorta
• Heart posterior,
pumps blood
forward.
• Blood empties
into coelom,
bathes tissues as
it flows to
posterior.
Insect Circulatory
System
Insect Respiratory System
• Air intake through spiracles on sides of abdomen.
• Air pulled into system of tubes (tracheae) that
transport air directly to tissues.
• Oxygen diffuses into tissues, CO2 out.
Nervous System & Sense Organs
• Nerve ganglia - “brain”
• Ventral Nerve cord.
• Tympanum - sound sensing organ on abdomen or
foreleg - not all insects have them.
Reproductive
System
• Sperm deposited into
female’s seminal
receptacle.
• Eggs fertilized
internally.
• Ovipositor used to
create hole in substrate
and/or deposit eggs.
Metamorphosis
Incomplete
• 3 stages – egg, nymph,
adult
• Nymph – immature form,
resembles adult, but w/
underdeveloped sexual
organs.
• Ex.- dragonflies,
grasshoppers, true bugs,
hoppers (Homoptera)
Complete
Metamorphosis
• 4 stages – egg, larva, pupa,
adult, each distinctly different.
• Larva – specialized for feeding
& growth.
• Pupa – transformation stage –
appears inactive, but big
changes internally.
• Adult – specialized for
dispersal, mating, & feeding –
different food than larva, no
competition.
• Butterflies, bees, beetles, flies.
Importance of
Metamorphosis
• One main factor in insect success.
• Can exploit seasonally-available foods.
• Different stages requiring lots of
energy are separate - no competition
between adults & larvae for food &
space.
• Insects can survive harsh weather as
eggs or pupae.
• Aggression – stings or
chemicals.
• Camouflage or hiding.
• Advertise danger
Mullerian mimicry – all
dangerous insects have
similar coloration –
predators only need to
learn once.
Batesian mimicry –
harmless insect evolves
to resemble dangerous
one. (monarch/viceroy)
Defense
Other Forms of
Mimicry
• Looking like part of the environment (stick,
leaf, thorn, etc.) helps insects escape notice.
Communication
• Social insects have the
most elaborate
communication.
• Communication may be
by scent (pheromones),
sound, touch, or light
(fireflies).
Social Behavior
• Includes ants, termites, and colonial bees and
wasps
• Caste system – division of labor
• Behavior is instinctive, not learned
• Workers –
responsible for all
tasks of the
colony except
reproduction.
• Drones – males,
mate w/ queen
(from another
colony)
• Queen – female,
reproduction only.
Honeybee
Castes
Workers
• Live about 6 wks.
• Tasks change w/ age.
• 1st task – “nurse” bees, feed larvae, drones, &
queen.
• Queen & youngest larvae get royal jelly.
• 2nd task – start producing wax to build &
repair honeycomb. Also remove waste &
dead bees, guard hive, & circulate air in hive.
• Last task – gather nectar & pollen
Queen
• Lives up to 5 yrs.
• Queen develops from larva fed a continuous diet
of royal jelly.
• Adult queen secretes “queen factor”, pheromone
preventing other female larvae from sexually
maturing.
• Mates once in her life on mating flight, stores
sperm to fertilize eggs for rest of life.
• Overcrowded hive, old queen takes half the
workers & swarms to start new colony. Worker
left behind produce more queens that fight for
dominance.
Drones
• Males, develop from unfertilized eggs.
• Large eyes – the better to see you with, my
queen!
• Contribute nothing to hive except
reproduction.
• Tolerated and fed by workers during
seasons of plenty, but killed or driven from
hive when food is scarce (winter).
• Only a few hundred drones, compared to
several thousand workers.
Waggle Dance &
Round Dance
• < of straight
run to vertical
equals <
between food
source to sun.
• # waggles in
straight run
indicates
distance.
• Round dance
indicates food
nearby, but
not direction.
Major Orders
• Orthoptera “straight-wing”
• Grasshoppers, crickets
• Strong, muscular hind legs for jumping
Major Orders
• Odonata – “toothed wing”
• Dragonflies, Damselflies
• Long, narrow, membranous wings
Major Orders
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Hemiptera – “Half-wing”
True bugs
Half-membranous, half-leathery forewings
Large triangle on back
Major Orders
• Homoptera – “Like-wing, same-wing”
• Cicadas, aphids, tree hoppers, frog hoppers
• Hold wings at angle over back to form “roof”
Major Orders
• Coleoptera – “sheath wing” – beetles
• Largest order, great diversity
• Forewings hard or leathery, cover most or all
of abdomen, meet in straight line on back
Major Orders
• Diptera – “two-wing”
• Flies, gnats, mosquitoes
• One pair of wings
Major Orders
• Hymenoptera – “Membrane-wing”
• Bees, ants, wasps
• Skinny “waist”
Major Orders
• Lepidoptera – “scale wing”
• Butterflies, moths
• Wings covered in scales