Post on 24-Feb-2016
description
ARTHROPODS PART 3
Subphylum MyriapodaClass Chilopoda: Centipedes
Active predators Feed mostly on earthworms & insects
Prefer moist places Bodies somewhat flattened
dorsoventrally Contain from a few to 177 segments Each segment bears one pair of
appendages 1st appendages modified to form venom claws
Sexes are separate All are oviparous
Producing eggs that hatch outside the body
“double-footed” Cylindrical bodes contain 25-100
segment Four thoracic segments bear one pair of
legs each Abdominal segments each have two
pairs Herbivores
Decayed plant & animal matter Prefer dark moist places
Subphylum MyriapodaClass Diplopoda: Millipedes
Millipede
Millipede
Millipede
Giant African Millipede
Subphylum MyriapodaClass Insecta: Insects
Most numerous & diverse of all arthropods ~1 million species named
Entomology Study of insects
Differ from other arthropods by: containing 3 pairs of legs 2 pairs of wings
Range from less than 1 mm to 20 cm in length Majority are less than 2.5 cm long
Distribution & Adaptability Live in all habitats that can support life
Only a few are marine Small size & well-protected eggs allow
them to travel great distances by wind, water, & other animals
Cuticular exoskeleton Gives insects much success
Subphylum MyriapodaClass Insecta: Insects
External Features Tagmata are head, thorax & abdomen Cuticle composed of 4 plates (sclerites)
Tergum – dorsal notum Ventral sternum Pair of lateral pleura
Legs are often modified for special purposes Terrestrial forms walking legs with terminal pads and
claws as in beetles Can be sticky for walking upside down (house fly) Hind legs adapted for jumping (grasshopper and crickets) First pair of legs modified for burrowing (mole cricket) Paddle-shaped for swimming (water bugs, many beetles) Forelegs modified for grasping pray (praying mantis)
Subphylum MyriapodaClass Insecta: Insects
House Fly
Grasshopper
Mole Cricket
Mole Cricket
Praying Mantis eating Grasshopper
Wings & the Flight Mechanism Wings may be:
Thin and membranous (flies) Thick and stiff (beetles) Parchment-like (grasshoppers) Covered with scales (butterflies, moths) With hairs (caddisflies)
Wing movement controlled by thoracic muscles Direct flight muscles
Attached to a part of the wing itself Indirect flight muscles
Not attached tot the wing Cause wing movement by altering the shape of the thorax
Subphylum MyriapodaClass Insecta: Insects
Direct Flight Muscles
Indirect Flight Muscles
Wings and Flight Mechanism Flight speeds vary
Fastest flyers usually have narrow, fast-moving wings with a strong tilt
Sphinx moths and horse flies are said to achieve about 48 km/hr (30 miles/hr)
Dragonflies 40 km/hr (25 miles/hr)
Subphylum MyriapodaClass Insecta: Insects
Reproduction – Sexes are separate Fertilization is internal They have various means of attracting mates:
Emit a chemical (pheromone) that can be detected for a great distance (moths)
Flashes of lights (fireflies) Sounds and color signals, etc
Sperm are stored in the seminal receptacle of a female numbers sufficient to fertilize more than one batch of
eggs Many insects mate only once during their lifetime
Subphylum MyriapodaClass Insecta: Insects
Behavior & Communication Responsive to stimuli are both internal
(physiological) or external (environmental) Much of the behavior is “innate”
entire sequences of actions apparently have been programmed
Insects communicate with other members of their species by chemical, visual, auditory, and tactile signals Chemical signals take the form of “pheromones” Sound production and reception is not present in all
insects Tactile communication includes tapping, stroking,
grasping, and antennae touching
Subphylum MyriapodaClass Insecta: Insects
Social Behavior Rank high in the animal kingdom in
the organization of social groups Some groups are temporary and
uncoordinated feeding gatherings of aphids
Some are coordinated for only a brief time
tent caterpillars that join in building a home web and a feeding net
Some have a complex social life honeybees, ants, and termites
Subphylum MyriapodaClass Insecta: Insects
Honeybees have one of the most complex social organizations in the insect world Organization continues for a more or less
indefinite period As many as 60,000 to 70,000 may live in a
single hive There are three casts
Queen – a single sexually mature female Drones – a few hundred sexually active males Workers – thousands of sexually inactive
genetic females Take care of young, secrete wax to build the six-sided
cells on the honeycomb, gather nectar from flowers, manufacture honey, collect pollen, and ventilate and guard the hive
Subphylum MyriapodaClass Insecta: Insects
Honeybees – Casts are determined partly by fertilization
and partly by what is fed to the larvae Drones develop parthenogenetically from
unfertilized eggs Queens and workers develop from fertilized
eggs “Royal jelly” is fed to larvae that will become queens “Worker jelly” is fed to ordinary larvae
Pheromones from the queen prevent female workers from maturing sexually
Subphylum MyriapodaClass Insecta: Insects
Beehive
Queen Bee
Drone Bee
Worker Bee
Worker bee with pollen