Download Phylum Arthropoda

Phylum Arthropoda
The largest group of animals
within this kingdom
• Arthropods are the
most biologically
successful group
• 1 million known
species of
arthropods
• They are suited for
life in most
conditions
Division of Arthropoda
• The phylum
arthropoda can be
divided into five
groups, or
subphylum:
–
–
–
–
–
Crustaceans
Centipedes
Millipedes
Arachnids
Insects
They All Share Certain
Characteristics . . .
•
•
•
•
•
Bilateral Symmetry
Coelomates
Segmented body
Organ / system level of organization
Complete digestive tract
What Separates Them From
Other Animals??
• Jointed appendages
• Exoskeleton
• Chitin and protein
• Well-developed
nervous system
• Distinct brain, nerve
cords
• Open circulatory
system
• Tubular heart and
arteries
Jointed appendages
• Legs are made up of
several pieces
• These pieces are
connected at hinged
joints
• Different arrangements
of these joints along
with opposing sets of
muscles allow different
functions
Arthropoda
= “jointed feet”
The
Exoskeleton
• Composed of protein
and chitin, a
carbohydrate
• Provides protection to
the soft body parts
• Prevents water loss
• Adaptation to life on land
• Exoskeletons do not
grow along with the
organism
» Molting – shedding
of the exoskeleton,
replacement with
larger one
Arthropods Are
Segmented . . .
• Segments are
modified and fused
• Form specific body
regions
– HEAD
• Six segments
• Contains specialized
mouth
• Antennae
• Compound eyes
– THORAX
• The middle region
– ABDOMEN
• The posterior region
Advancements in the Nervous
System
• Cephalization is extensive
– Disinct anterior region
– Most sensory organs located in anterior
region
• Well-developed sensory organs
– Eyes
– Receptors for smell
– Antennae to respond to touch
All Arthropods Have an Open
Circulatory System
• Tubular heart located
dorsally
– Above digestive tract
• Transport medium called
hemolymph
• Arteries carry
hemolymph away from
heart
– Flow into spaces
surrounding tissues and
organs
• Hemolymph brought
back to the heart
through pores equipped
with valves
Arthropoda : Reviewing
Their Success
• Their success has
been brought about
by several
evolutionary events
– Exoskeleton acting as
a cuticle
– Segmentation and
appendages
– Extensive nervous
system and behaviors