Diversity of Diversity of ArthropodsArthropods

4 Subphyla4 Subphyla Trilobita- Extinct TrilobitesTrilobita- Extinct Trilobites Chelicerata- Spiders, Scorpions, and Chelicerata- Spiders, Scorpions, and

TicksTicks Crustacea- Shrimp, lobster, crayfish, and Crustacea- Shrimp, lobster, crayfish, and

barnaclesbarnacles Uniramia- Insects, Centipedes, and Uniramia- Insects, Centipedes, and

MillipedesMillipedes

Subphyla TrilobitaSubphyla Trilobita EXTINCTEXTINCT MarineMarine Head and Head and

Segmented trunk Segmented trunk with one pair of legs with one pair of legs per segmentper segment

Single pair AntennaeSingle pair Antennae GillsGills

Subphyla ChelicerataSubphyla Chelicerata 2 classes 2 classes

Xiphosura- Horseshoe Crab Xiphosura- Horseshoe Crab Arachnida- Spiders, Scorpions, Ticks and Arachnida- Spiders, Scorpions, Ticks and

MitesMites

Chelicarata Chelicarata CharacteristicsCharacteristics

Two SegmentsTwo Segments Cephalothorax Cephalothorax Abdomen Abdomen

No AntennaNo Antenna Simple Eyes called OcelliSimple Eyes called Ocelli Six pairs of Jointed AppendagesSix pairs of Jointed Appendages

Chelicerae- Claws or Fangs (1 pair)Chelicerae- Claws or Fangs (1 pair) Pedipalps- Feeding, Walking, Sensing (1pair)Pedipalps- Feeding, Walking, Sensing (1pair) Walking Legs- Movement (4 pair)Walking Legs- Movement (4 pair)

Chelicerata Cont…Chelicerata Cont… Phylum ArthropodaPhylum Arthropoda

Subphyla ChelicerataSubphyla Chelicerata Class XiphosuraClass Xiphosura Class ArachnidaClass Arachnida

Order AranaeaOrder Aranaea Order ScorpionidaOrder Scorpionida Order AcariOrder Acari

Horseshoe CrabsHorseshoe Crabs Class XiphosuraClass Xiphosura NOT TRUE CRABSNOT TRUE CRABS MarineMarine Book Gills for breathingBook Gills for breathing

Class ArachnidaClass Arachnida TerrestrialTerrestrial 8 Legs8 Legs Chelicerae or Fangs with VenomChelicerae or Fangs with Venom OcelliOcelli No AntennaNo Antenna Breathe through Book LungsBreathe through Book Lungs

(Some species may have tracheal tubes)(Some species may have tracheal tubes)

SpidersSpidersOrder AranaeaOrder Aranaea

8 simple eyes (ocelli)- Detect light, do not form 8 simple eyes (ocelli)- Detect light, do not form imagesimages

6 pairs of appendages6 pairs of appendages 11stst pair: Chelicerae, modified pincers to hold/handle pair: Chelicerae, modified pincers to hold/handle

food or fangs to inject venomfood or fangs to inject venom 22ndnd pair: Pedipalps- handle/sense food, some males pair: Pedipalps- handle/sense food, some males

use to deliver sperm during reproductionuse to deliver sperm during reproduction 33rdrd-6-6thth pair: legs used for locomotion, located on pair: legs used for locomotion, located on

cephalothoraxcephalothorax

Spiders Cont…Spiders Cont… Fangs pierce prey, inject poison, & suck out Fangs pierce prey, inject poison, & suck out

body fluids (feed primarily on insects, a few body fluids (feed primarily on insects, a few species feed on small vertebrates)species feed on small vertebrates)

Have silk glands to make silk & spinnerets to Have silk glands to make silk & spinnerets to release silk for webs release silk for webs

Lay eggs in silken sacs, young resemble adults Lay eggs in silken sacs, young resemble adults and are often cannibalisticand are often cannibalistic

Most spiders are solitary except at matingMost spiders are solitary except at mating

Ticks and MitesTicks and MitesOrder AcariOrder Acari

Most abundant ArachnidMost abundant Arachnid Only 1 body section-Head, thorax, and Only 1 body section-Head, thorax, and

abdomen are completely fusedabdomen are completely fused Ticks are external parasitesTicks are external parasites

Can be found on reptiles, birds and mammalsCan be found on reptiles, birds and mammals Mites are small and often invisible to naked Mites are small and often invisible to naked

eyeeye Parasitic while some adults can be free-livingParasitic while some adults can be free-living

ScorpionsScorpionsOrder ScorpionidaOrder Scorpionida

Multiple body segmentsMultiple body segments Cephalothorax and long segmented abdomenCephalothorax and long segmented abdomen

Pedipalps modified into Enlarged PincersPedipalps modified into Enlarged Pincers Up-Curved tail ends with a poisonous stingerUp-Curved tail ends with a poisonous stinger Common in southern and southwestern United Common in southern and southwestern United

StatesStates Nocturnal, feed mostly on insects and spidersNocturnal, feed mostly on insects and spiders Breathe through Book LungsBreathe through Book Lungs Give birth to live youngGive birth to live young

Subphyla UniramiaSubphyla Uniramia 3 Classes3 Classes

Chilopoda- centipedesChilopoda- centipedes Diplopoda- millipedesDiplopoda- millipedes Insecta- insectsInsecta- insects

CentipedesCentipedesClass ChilopodaClass Chilopoda

Are carnivores, also eat soil arthropods, Are carnivores, also eat soil arthropods, snails, worms, and slugssnails, worms, and slugs

They biteThey bite Have 1 pair of legs per segment; have 15 Have 1 pair of legs per segment; have 15

to 181 segments (always odd numbers); to 181 segments (always odd numbers); 11stst segment has a pair of poison claws segment has a pair of poison claws

    Have tracheal tubes w/ 1 pair of Have tracheal tubes w/ 1 pair of spiracles on each segmentspiracles on each segment

Most lay eggsMost lay eggs

MillipedesMillipedesClass DiplopodaClass Diplopoda

Eat plants and dead materialsEat plants and dead materials Have 2 legs per segment; can have 100+ Have 2 legs per segment; can have 100+

segments; segments;   Have tracheal tubes; each segment has 2 Have tracheal tubes; each segment has 2

spiraclesspiracles do not bite do not bite   spray obnoxious smelling fluid as defense spray obnoxious smelling fluid as defense

mechanismmechanism lay eggs in a nest and guard themlay eggs in a nest and guard them

InsectsInsectsClass InsectaClass Insecta

Entomology – study of insectsEntomology – study of insects Largest group of arthropodsLargest group of arthropods Generally have 3 pair legs, usually 2 pair of Generally have 3 pair legs, usually 2 pair of

wings, 1 pair antennae and 3 body regionswings, 1 pair antennae and 3 body regions Mate once or only a few timesMate once or only a few times Internal fertilization, shell forms around them, Internal fertilization, shell forms around them,

then female lays eggs (large number increases then female lays eggs (large number increases chance of survival)chance of survival)

MetamorphosisMetamorphosis Most go through a metamorphosis – series of changes, Most go through a metamorphosis – series of changes,

controlled by hormones. controlled by hormones. Usual 4 stages of developmentUsual 4 stages of development

1.egg1.egg2.larva - free-living, wormlike stage2.larva - free-living, wormlike stage3.pupa – period of reorganization; larva organs and 3.pupa – period of reorganization; larva organs and tissues breakdown and are replaced w/adult tissuestissues breakdown and are replaced w/adult tissues4.adult4.adult

Complete metamorphosis is an advantage because Complete metamorphosis is an advantage because young do not young do not compete w/adults for food.compete w/adults for food.Example – caterpillar to butterflyExample – caterpillar to butterfly

Caterpillar > ButterflyCaterpillar > Butterfly In pupal stage, larval tissues break down & cells In pupal stage, larval tissues break down & cells

called imaginal disk develops into tissues of the called imaginal disk develops into tissues of the adultadult

Cocoon or chrysalis is a protective case formed Cocoon or chrysalis is a protective case formed around the pupaaround the pupa

Metamorphosis controlled by hormonesMetamorphosis controlled by hormones Different stages have different functions Different stages have different functions

(caterpillar/growth & adult/reproduction)(caterpillar/growth & adult/reproduction)

Insects Cont…Insects Cont… Many other insects go through 3 stages – gradual or Many other insects go through 3 stages – gradual or

incomplete metamorphosisincomplete metamorphosis 1. egg1. egg

2.nymph – looks like adult but smaller, lacks certain 2.nymph – looks like adult but smaller, lacks certain appendages and cannot reproduce.appendages and cannot reproduce.3.adult3.adult Example – grasshoppers or cockroachesExample – grasshoppers or cockroaches

Respiratory system is a tracheal system with spiraclesRespiratory system is a tracheal system with spiracles Have both compound and simple eyes, most adults Have both compound and simple eyes, most adults

have just 2 compound eyes that may cover much of the have just 2 compound eyes that may cover much of the headhead

Success of InsectsSuccess of Insects Found everywhere except in deep part Found everywhere except in deep part

of oceanof ocean Very short life span & rapidly adapt to Very short life span & rapidly adapt to

new environmentsnew environments Small size helps minimize competition Small size helps minimize competition

in habitatsin habitats Flight helps escape predators & move Flight helps escape predators & move

into other environmentsinto other environments

Defense MechanismsDefense Mechanisms Wasps & bees can stingWasps & bees can sting Some insects use camouflage to Some insects use camouflage to

blend into their environmentsblend into their environments Some insects taste bad & have Some insects taste bad & have

warning colorationswarning colorations Some insects spray noxious chemicals.Some insects spray noxious chemicals.

Environmental ImpactEnvironmental Impact Pollinate almost 2/3's of all plantsPollinate almost 2/3's of all plants Serve as food for fish, birds, & mammalsServe as food for fish, birds, & mammals Help recycle materials (termites recycle Help recycle materials (termites recycle

wood)wood) Make useful byproducts such as silk & Make useful byproducts such as silk &

honeyhoney Some spread diseaseSome spread disease Agricultural pestsAgricultural pests

Crabs, Lobsters, Crayfish, & Crabs, Lobsters, Crayfish, & ShrimpShrimpSubphyla CrustaceaSubphyla Crustacea

Most are aquatic, w/gillsMost are aquatic, w/gills Have mandibles for crushing food; move side to side Have mandibles for crushing food; move side to side

instead of up and downinstead of up and down 5 pair walking legs used for walking, for seizing prey, 5 pair walking legs used for walking, for seizing prey,

and for cleaning other appendagesand for cleaning other appendages 1 pair antennae and 1 pair antennules1 pair antennae and 1 pair antennules 2 compound eyes which are usually on movable stalks2 compound eyes which are usually on movable stalks Swimmerets, located on abdomen, create water Swimmerets, located on abdomen, create water

currents, which enhance aeration of gills; some currents, which enhance aeration of gills; some females use them to hold eggs until hatching, males females use them to hold eggs until hatching, males use it as a copulatory structureuse it as a copulatory structure