Phylum ArthropodaPhylum Arthropoda(The Arthropods)(The Arthropods)

•By far and away, the most successful animal group ever to live•Consists of over 1 million named species, 2 of every 3 animals are arthropods. ~ 1018 individuals.

–Inhabit all ecosystems•General characteristics•All have a hard exoskeleton•Composed of protein and chitin

–Allows for great variation in function - biological "swiss army knives"–Must molt as they grow–Limits their size

•Have well developed body segments and appendages•Have well developed sensory organs including true eyes and antennae•Have open circulatory systems & special gas exchange organs

Could this be possible?Could this be possible?

Subphylum Chilicerata (arachnids, horseshoe crabs & sea spiders)

• Divided into 3 classes; Arachnida, Merostomata & Pycnogonida

• Body divided into 2 regions– Abdomen– Cephalothorax (fused head & thorax)

• Lack jaws• Have 6 appendages & no antennae

– First appendages form chilicerae (frequently fangs)

Class Class ArachnidaArachnida (Spiders, Scorpions, Ticks & Mites)(Spiders, Scorpions, Ticks & Mites)

• Very diverse classVery diverse class• Most species parasitic Most species parasitic

or predatoryor predatory• Many possess Many possess book book

lungslungs for gas exchange for gas exchange• Spiders are able to Spiders are able to

produce a strong produce a strong polymer - polymer - silksilk

• ChiliceraChilicera in form of in form of fangs fangs

SpidersSpiders

More Spiders…

TarantulaTarantula

Black WidowBlack Widow

For the true For the true arachnophobe…arachnophobe…

The brown recluse and its bite woundsThe brown recluse and its bite wounds

The Camel SpiderThe Camel Spider

Ticks & MitesTicks & Mites

Ticks & Lyme Ticks & Lyme Disease…Disease…

Common MitesCommon Mites

Dust MiteDust Mite Common MiteCommon Mite

ScorpionsScorpions

Class PicogonidaClass Picogonida(Sea Spiders)(Sea Spiders)

Class MerostomataClass Merostomata

• Ancient group of Ancient group of speciesspecies

• Changed little over Changed little over 350 million years350 million years

• Aquatic, mostly Aquatic, mostly found on Atlantic & found on Atlantic & gulf coasts of gulf coasts of United States United States

Subphylum UniramaiSubphylum Uniramai(3 Classes)(3 Classes)

• Class Insecta (insects)

• Class Chilopoda (Centipedes)

• Class Diplopoda (Millipedes)

Class Insecta Class Insecta (the insects)(the insects)

• Far & away the most diverse of animal Far & away the most diverse of animal groupsgroups– More types of insects alone than all other More types of insects alone than all other

animal groups combinedanimal groups combined– Inhabit all terrestrial & freshwater Inhabit all terrestrial & freshwater

ecosystems.ecosystems.– Success largely attributed to coevolution Success largely attributed to coevolution

with flowering plants.with flowering plants.

Insect Body PlanInsect Body Plan• Insects have 6 legsInsects have 6 legs• 3 body parts3 body parts

– HeadHead– ThoraxThorax– AbdomenAbdomen

• Most insects have wings, however in many species these are vestigalMost insects have wings, however in many species these are vestigal• Have advanced excretory system composed of Have advanced excretory system composed of malphygian tubulesmalphygian tubules• Exchange gasses through a complex Exchange gasses through a complex tracheal systemtracheal system

VisionVision

• Have complex compound eye which is usually extremely sensitive to motion and allows 3600 vision

• Most insects see well into the UV spectrum

Feeding / MouthpartsFeeding / Mouthparts

• Insects usually have specialized jaws/mouthparts suited to their ecological niche

MetamorphosisMetamorphosis

• Most insects undergo a process of metamorphosis - 2 types

• Incomplete metamorphosis– Larva similar to adult, with differing body proportions– Undergoes a series of molts resulting in adult phenotype

Complete MetamorphosisComplete Metamorphosis• Larva is very unlike adult phenotype• Envelopes self in a coccoon or chrysalis where

body breaks-down and reforms into adult form.

Classes Chiopoda & DiplopodaClasses Chiopoda & Diplopoda

• Millipedes (Millipedes (diplopodadiplopoda) are segmented worm-like animals) are segmented worm-like animals– Have 2 pairs of legs per segmentHave 2 pairs of legs per segment– Primarily herbivores & decomposersPrimarily herbivores & decomposers

• Centipedes (Centipedes (ChilopodaChilopoda))– Usually terrestrial carnivoresUsually terrestrial carnivores– Have 1 pair of antennaeHave 1 pair of antennae– Are often poisonous, using modified front claws to immobilize preyAre often poisonous, using modified front claws to immobilize prey

Centipedes vs. MillipedesCentipedes vs. Millipedes

CentipedeCentipede MillipedeMillipede

Subphylum Crustacea

• Includes crabs, Includes crabs, lobsters, crayfish, lobsters, crayfish, shrimp, krill & shrimp, krill & barnaclesbarnacles

• Over 40,000 Over 40,000 speciesspecies

• Appendages are Appendages are often highly often highly specializedspecialized

• Gas exchange is Gas exchange is usually through usually through gillsgills

• Many species taste delicious in butter

Some Crustaceans

Marine Maine Lobster

Crayfish

Crabs

BarnaclesBarnacles