Spiders, insects, centipedes, scorpions, shrimp, crabs,

lobsters, butterflies

The world arthropod population has been estimated at a billion billion

•Jointed appendages

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Major Characteristics:•Segmented bodies covered in an exoskeleton

of chitin (Carbohydrate).•Protosome coelomate

•Three segments: •Head, Thorax, Abdomen

Chitin

• Strong but flexible • Nitrogenous polysaccharide.

ExoskeletonExoskeletonProtectionhelps prevent water lossprovides framework for muscle attachmentDoes not grow. When the organism outgrows it, it molts.

oGland digest inside of old exoskeleton and then other glands secrete a new skeleton.oWhen new one is ready, organism pulls out of the old.

Have more sensory apparatus than the annelids gives them more speed and freedom of

movement

Groups of segments and their appendages Groups of segments and their appendages have become specialized for a variety of have become specialized for a variety of functions, permitting efficient division of functions, permitting efficient division of

labor among regions. labor among regions.

Nervous System Arthropods have a well-developed nervous system. •A brain is connected to a pair of ventral nerve cords with several segmental ganglia.

– Chords meet in the head, where the ganglia from several anterior segments are fused into a cerebral ganglion (brain).

– Close to the antennae, eyes, and other sense organs concentrated on the

head.

Nervous System

Digestion• Grasshopper:

– Long tube containing crop & gizzard– Specialilzed mouth parts for tasting, biting &

crushing

Reproduction

•Metamorphosis

(Insects)

•Adult stage and

larval stage do not

compete for food.

Short generation time

•Mouth Parts•Many different types- enabled them to occupy any niche

•Metamorphosis.•Process of changing shape and form.

Two types:Two types:Complete•Larvae look completely different from adultIncomplete•Larvae look like a small adult- lack sex organs

Metamorphosis is central to insect development.– Larval stages specialized for eating and

growing change morphology completely during the pupal stage and emerge as adults.

Feeding:

Can be

herbivores,

carnivores,

and

omnivores.

Respiration:•Most have tracheal tubes

that extend throughout the body. Air enters through spiracles.

•Spiders- book lungs/gills.

Tracheal tubes- respirationComplex mouth parts

Three parts specialized for diet

chitin-lined tracheal system carries O2 from the spiracles directly to the cells.

Respiration:

CirculationCirculationWell developed heart with arteries and

vessels

oOpen circulatory system in which hemolymph fluid is propelled by a heart through short arteries into sinuses (the hemocoel) surrounding tissues & organs.

oHemolymph returns to the heart through valved pores.

Hemocoel- internal cavity which bathes tissues w/an O2 & nutrient carrying fluid called hemolymphOpen systems are also seen in

mollusks

In an open circulatory system, blood leaves the blood and flows freely within the tissues. This system is not very efficient because there is no blood pressure to move blood rapidly through the tissues. The oval line in the diagram below represents an animals body.

Removal of wasteMalpighian tubules

(outpockets of the digestive tract) Aquatic – Tubules excrete directly into water

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All extinctWere marine

arthropods about 500 million years

ago. Became extinct 200 million

years ago.

Major Groups:Classified based on number and structure of Classified based on number and structure of

body segments.body segments.4 subphylum, 10 classes

•Lobster, crab, shrimp, Crayfish, Barnacles•4 classes•Mainly aquatic (Marine and freshwater)•Terrestrial -Pill bugs

• 2 or 3 body segments

• Head-compound eyes

• 2 pairs of branched antennas

• Chewing mouth parts-mandibles

2 major body parts1.Cephalothorax -Fusion of head w/thorax -Covered by a

carpace.2. Abdomen

name is derived from the crusty exoskeleton

• Head usually bears compound eyes and five pairs of appendages

• a. First two are antennae and antennules; in front of the mouth, they have sensory functions.

• b. Three pairs (mandibles, first and second maxillae) lie behind mouth and are used in feeding.

“Spiders and their relatives”3 classes

•Have twotwo mouth parts: •Cheliceras-fangs-stab and paralyze•Pedipalps- to grab prey

•Two body segments•Cephalothorax and abdomen

•Almost all have four pairs of walking legs•Book lungs or book gills

Lycosid spider: female with offspring

Spiders, scorpions, mites, ticks

SpidersBook LungsInject digestive

enzymes into preyAll spiders

produce silk- may not make webs

Spin webs by forcing liquid silk through their spinnerets

Mites and TicksUsually parasiticMouth parts, usually needle-like, are used to dig into host tissue and suck blood.

TicksTicks- Transmit bacteria that causes Lyme Disease & Rocky mountain spotted

feverMitesMites- chiggers can cause itching and painful rashes

in humans.

Scorpions

Stingers can kill or paralyze

prey. Chew their prey.

•Three body regions•Head, thorax, abdomen•Three pairs of legs attached to thorax. Jumping, walking or capturing prey.•Pair of antennae for sensing the environment• Pair of compound eyes on head•Two pairs of wings (chitin) on thorax•Flying-wider variety habitats

“Insects and their relatives”

Beetles, Flies, Butterflies, Ants, Grasshoppers, Fleas, Crickets, Mosquitoes, bees

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Insect Eyes

Insects and

Humans

DOWNSDOWNS•Termites destroy wood

•Moths eat cloth

•Locusts destroy crops

•Cotton Boll Weevils

•Mosquitoes and diseases

UPSUPS•Bees,

butterflies, etc., pollinate crops•Some produce silk, wax, honey

•Food

Insects and communication

Sounds- chirps, buzzLight- Male fireflies

Chemicals- Pheromones (mate, danger, or alert)

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Insect SocietiesInsect Societies•Complex group that works together for the good of the colony.•Different roles are preformed by groups called castes.•Each castes has a different body form to carry out their specific task.

Carpenter ant castes, from left to right: queen, winged male, major

worker, minor worker

•Bees Dance!•Ants leave pheromone trails.

•Very sophisticated communication.

“Dances With Bees”

ROUND DANCE-used when the source of food (nectar or pollen) is less than 100 metres away

WAGGLE DANCE

Animation

Millipedes•Each body segment has two pairs of legs•Detritivores- live under rocks and in decaying logs•Some can secret unpleasant or toxic chemicals for defense.

slow-moving vegetarians scavengers

Centipedes•Each body segment has one pair of legs•Carnivores•Mouth parts contain venomous claws•Live under rocks or in the soil•Must live in moist environments because their spiracles cannot close and they lack a waterproof coating.

move rapidly and prey mostly on small invertebrates.

feedon

respireusing

reproduceusing

havewell-developed

Anthropods

Internalfertilization

All typesof foods

Externalfertilization

Heart Brain MusclesTrachealtubes Book lungs

Book gills