Transcript Features of Arthropods – jointed legged animals

Features of Arthropods –
jointed legged animals
Section 30.1
Arthropod Diversity
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All have jointed appendages – legs, antennae,
and mouth parts
The largest group of animals – more
arthropods than all other groups combined
Divided into two groups: those with jaws and
those with fangs or pincers
Arthropod Body Plan
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Jointed appendages
Segmentation
Distinct head, often with compound eyes
Exoskeleton – composed of chitin
Respiration by gills, tracheae, or book lungs
Open circulatory system
Excretion through Malpighian tubules
Many have wings
Segmentation
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Individual segments exist only during larval
stage
In adults the segments fuse to form three
distinct regions: head, thorax, abdomen
In some the head and thorax fuse to form a
cephalothorax
Three body parts – head, thorax,
abdomen
Cephalothorax – combines head and thorax
with a separate abdomen
Compound eyes
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Each individual unit has its own lens and
retina
Brain combines information to form an image
Very good for sensing movement
Some also have simple eyes which function in
stabilization during flight
House fly’s compound eye
Exoskeleton
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Protects internal organs & prevents drying
Flexible at the joints
Muscles are attached to the interior
Molting sheds the exoskeleton during growth
Arthropods must molt their
exoskeletons as they grow
Respiration
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Land arthropods use a network of tubes called
tracheae which are connected to the outside
by spiracles
Aquatic arthropods use gills
Some have book lungs – flattened stacks of
thin tissues that absorb oxygen
Insect trachea and spiracles
Excretion
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Kidney-like tubes called Malpighian tubules
These extend from the gut and are bathed with
blood
Wastes enter by diffusion and leave through
the anus
Malpighian tubules remove wastes