Crustaceans, Spiders and Insects

Arthropods are the most successful phylum on the planet!

750,000 species

Arthropods haveSegmented bodyTough exoskeletonJointed appendages

Feeding – complex mouthparts to eat a wide range of food

Respiration Land – air enters through spiracles – holes in the side of the

body. Water – gills or book gills

Circulation – open circulatory system – open sinusesExcretion – Malpighian tubules – saclike organ that

combines urine and waste togetherResponse – have a brain! Sophisticated eyes and

taste receptorsMovement – have muscles…can flex and extendReproduction – internal or external reproduction

depending on the species

1. Crustaceans – primarily aquaticExamples: crabs, shrimps,

crayfishes and pillbugs.Characteristics:

Two pairs of antennae 2 or 3 body sections –

Cephalothorax/Abdomen Chewing mouthparts called

mandibles

Molting – when arthropods outgrow their exoskeleton

Steps to molting1. skin glands digest

inner part of exoskeleton2. other glands create a

new exoskeleton3. animal pulls itself out

of old skeleton4. While new skeleton is

soft – animal fills it with air to allow for growth

2. Spiders and their relatives Characteristics

No antennaeCephalothorax and abdomen2 pairs of mouthpart appendages

Chelicerae – fangs to stab and paralyze preyPedipalps – grab prey

Spiders are in the class ArachnidaSpiders have no jaws so they liquify their

preyScorpions are found in warm climates.

The abdomen has a stinger that can kill and paralyze prey.

3. Insects – There are 3 classes of Insects

1. Chilopoda – centipedes 2. Diplopoda – millipedes 3. Insecta – the insects1. Centipedes – • each body segment has

one pair of legs carnivores live beneath rocks or in

the soil2. Millipedes – each body

segment has two pairs of legsDragon Millipede – produces cyanide when threatened.

Insects have a body divided into three parts

Head – antennae and eyesThorax - three pairs of legs,

wingsAbdomen – stinger or poison

gland

Insects undergo metamorphosis – a process of changing shape and form.

1.Incomplete Metamorphosis – Young (called nymphs) look very much like the adults.

Examples: Grasshoppers

2. Complete metamorphosis – dramatic change in body form. Eggs—Larvae—Pupa—Adult

Examples: bees, moths, beetles, butterflies, flies