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
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