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Phylum Arthropoda
Includes:

Insects

Centipedes

Spiders

Ticks

Scorpions

Lobsters

Crabs
Phylum Arthropoda
Includes a diverse group of animals which vary
greatly in structure and habitat.
Found in every Major Biome.
Arthropods

There are over
1,000,000 species

Invertebrates

Bilateral Symmetry

Exoskeleton

Jointed appendages

Segmented Body
Jointed Appendages


Allow greater freedom
of powerful
movement.
For some the first pair
of appendages
evolved into a
chelicerate (B), (like
in scorpions and
spiders) are used to
manipulate food.
Exoskeleton Advantages



Is a hard, thick outer
covering made of
protein and Chitin.
Protects internal
organs, allow a place
for muscle
attachment.
Prevent water loss
Exoskeleton Disadvantages




Does not grow with the
rest of the body, so
Arthropods must shed
their exoskeleton from
time to time as they grow
called Molting
The new is produced
beneath the old one.
After the old one sheds
the new one hardens
Most Arthropods molt an
average of 4 to 7 times
per year.
Movement
-Quick, Active Animals
-They crawl, swim, dig
and fly
-So arthropods have
efficient respiratory
organs that quickly
deliver oxygen to their
tissue.
Respiratory Organs
Arthropods have evolved Three types of
respiratory organs:
1. Gills
2. Tracheal tubes
3. Book lungs
1. Gills
Aquatic arthropods
exchange gases
through gills- which
extract oxygen from
water and release
carbon dioxide into the
water.
2. Tracheal tubes
Most Terrestrial INSECTS have tracheal tubes (Q&Q1)branching network of hollow passages that carry air
throughout the body.
Muscle activity helps pump the air through the tubes, Air
enters and leaves the tubes through tiny openings in
the thorax and abdomen called spiracles (P)
3. Book Lungs
Most SPIDERS have
book lungs (S&S1)air filled chambers that
contain leaf-like
plates.
The staked plates
(folded membranes)
increase the surface
area to allow for better
gas exchange
between air and
blood.
Nervous System
Well-developed
Consists of 1) double
ventral nerve cord
(G),2) Anterior brain
(A), and 3) Several
Ganglia (D,E,E1,E2,F)
Ganglia- act as control
centers for the body
section in which they
are located.
Nervous System- Sensory Organs
Most Arthropods have
-One pair of large
compound eyes
OR
- Three to Eight simple
eyes
Simple Eyes vs. Compound Eyes
Simple Eyes are used
to detect light,
while Compound Eyes
are better at detecting
motion as well as
colors
However, the images
are not as sharp as
the images produced
by human eyes.
Compound Eye
Circulatory System
Blood is pumped by One or MORE hearts (M) in
an OPEN circulatory system.
Circulatory System
1. Blood is pumped by the hearts (M) through vessels
into tissue spaces
2. Blood bathes the tissues and returns to the dorsal
aorta(heart) through open body spaces (O)
3. The blood enters into the heart through tiny openings
called ostia (L1).
Digestive System
-Includes a Mouth (A), Pharynx (C), Esophagus
(D), Crop (E), Gizzard (F), Midgut (G), Intestine
(H&I) and Anus (J)
-Several Digestive Glands (B&G1) produce
digestive enzymes that are involved in chemical
digestion.
Nutrition
Some arthropods are
herbivores (ex
Butterflies)
Other are Mostly
carnivores (ex
spiders)
Many are Omnivores
(ex ants)
Excretory System
Tube-like structures called Malpighian tubules
(K)- absorb waste materials from the blood and
empty them into the intestinal tract.
Reproduction
Reproduce sexually.
MOST have separate
sexs male and female.
Fertilization is usually
Internal in land
species and External
in aquatic species.