Phylum Arthropoda

• Includes insects, spiders, crayfish,…

• Most successful animal group

Arthropods are the most diverseGroup of animals.

They live in the land, sea, and air!

There are approximately 900,000 species of arthropods!

They vary in size from about8 micrometers to about

12 feet across!

Arthropods have 8 similar Characteristics…

Jointed AppendagesSegmentation

Distinct Head with Compound EyesExoskeleton

Tracheae Open Circulatory System

Malpighian TubesWings

Appendages are structures thatExtend from the arthropod’s

Body wall.

They are basically jointed foot.

• Antennae-

Segmentation

• Two sets of eyes:– Ocelli– Compound

Skeletal

• Exoskeleton• Made of Chitin

Growth and Development

As arthropods grow they have toCreate a new exoskeleton,

This is molting.

Adult breaks through ecdysial [ek-diz-ee-al]

suture in the insect exoskeleton

Cicada MoltingCicada Molting

Respiratory System• Varies:

Crabs and shrimp = gills

Horseshoe crab = book gills

• Insects use trachea - a network of fine tubes– Spiracles - tiny holes where air enters

Pg 686

Digestive System

• Tube-in-a-tube

• Malpighian Tubules– Absorb nutrients and pass– Them through anus

• All eating habits– Locust = herbivores– Scorpion = carnivore– Ticks and fleas = parasites

• Mouth adapted to food source

Spiders have mouthparts calledChelicerae, or fangs.

The second set of appendages arePedipalps which are used to

Catch and handle prey.

Only 2 species of spiders in the US Are poisonous to humans,

The Black Widow And

The Brown RecluseBoth are here in Ohio.

They build webs from spinneretsLocated at the end of the

Abdomen.

Spiders wrap prey in their silkAnd suck out their insides.

Scorpions and mites are arachnids.

Fleas and ticks are mites.Mites are the major cause ofIndoor allergies in humans.

Subphylum Uniramia

• Centipedes, millipedes, and all insects

• One pair antennae; two pair wings

• Appendages do not branch

Most insects have chewing Mouthparts called mandibles.

Most scientists agree that thereAre more than 700,000 species.

The insect life cycle is complex.

There are several molts and in theEnd there is a dramatic

Metamorphosis.

There are 2 kinds of metamorphosis,Complete and incomplete.

Complete

(egg— larvae— pupa—adult)

Incomplete

• Tympanum (eardrum)

Subphylum Crustacea• Crayfish & lobster• Two pair antennae• 10 footed• Pinchers used to obtain food• Two body sections (head &

thorax are fused= cephalothorax)