Arthropods - An Introduction

The Most Successful Animals on EarthThe Most Successful Animals on Earth

VARIETY

Hermit Crab

Fairy Shrimp

Centipede

Horseshoe

Crab

Size

What Is Different about Each of These Animals?

Color

Shape

Method of Movement

What Do These Animals Have In Common?

Jointed Legs

Exoskeleton

Segmented Body

Distinct Head

Compound Eyes (most cases)

Centipedes, Millipedes, Sow Bugs, Pill Bugs

Myriapods

Crustaceans

Crayfish, Lobsters, Crabs, Shrimp

Mouthparts modified into pincers or fangs

Head, Cephalothorax,

(Thorax & Abdomen fused together)

6 – 8 Pairs Simple Eyes

4 Pairs (8) Walking Legs

Some have Stingers

Carnivores

Terrestrial

SPINNERETS

Scientists at NASA wondered what happens when you get a spider stoned.

The experiments show that common house spiders spin their webs in different ways according to the psychotropic drug they have been given. They discovered the more toxic the chemical, the more deformed was the web.

Spiders on marijuana started spinning webs but appeared to lose concentration about half-way through.

Those on Benzedrine - "speed" - spin their webs "with gusto, but without much planning leaving large holes”.

Caffeine makes spiders incapable of spinning anything better than a few threads strung together at random.

On chloral hydrate, an ingredient of sleeping pills, spiders "drop off before they even get started".

Most Numerous of All Animals

Has A Three Part Body Plan

Head, Thorax, AbdomenLife Cycle is Metamorphosis –

Complete & Incomplete

First Animals to Fly – Most Adults Do Fly

Divided Into Many Orders

O R D E R S

COLEPTERA – Beetles, Weevils (Shield Wing)

DIPTERA – Flies, Mosquitoes ( 2 Wings)

LEPIDOPTERA – Butterflies, Moths (Scaled Wing)

COMPLETE METAMORPHOSIS

HYMENOPTERA– Bees, Wasps, Ants (Membrane Wings)

ORTHOPTERA – Grasshoppers, Crickets (Leather Wings)

HEMIPTERA – True Bugs (Half Wings)

Catherine Patterson

Santa Rita High School - 2007