Arthropoda is the largest and most successful phylum in the world. Here are the slides that can help you understand the basics of this phylum. Hope it will be helpful for you!

1. PHYLUM ARTHROPODA
The Life of Creepy Crawlies

2. AREAS TO BE DISCOVERED
Blueprint for success
Classification
Metamerism & Tagmatization
Exoskeleton
Metamorphosis

3. INTRODUCTION
• Arthropoda is the largest phylum with
about nine lakh species.
• They may be aquatic, terrestrial or even
parasitic.
• They have jointed appendages and a
chitinous exoskeleton.
• This phylum includes several large
classes and contains the class Insecta
which itself represents a major portion of
the animal species in the world. They
possess the ability to survive in every
habitat.

5. BLUEPRINT FOR SUCCESS
• Almost any way you look
at them, arthropods are
successful:
• They have been around for
more than 500 million years
and are still evolving.
• They live on Earth in
overwhelming numbers.
• They have come in all
shapes and sizes.
• They have evolved to fill a
variety of ecological niches
— from tiny internal
parasite to giant bird-eating
predator.

6. CLASSIFICATION-
CRUSTACEA
• They are aquatic, terrestrial, or parasitic.
• The head is fused with the thorax region known as the
cephalothorax.
• Respiration occurs through gills or general body surface.
• The body is covered by a single large carapace.
• They possess two pairs of antennae and five pairs of appendages.
• They have a pair of compound eyes and gonopores.
• Development is indirect. Larval stage is present.
• Eg., Daphnia, Palaemon
• The subphylum Crustacea is divided into six classes-
 Branchiopoda
 Remipedia
 Chephlocarida
 Maxillopoda
 Ostracoda
 Malacostraca

8. MYRIAPODA
• These are mostly terrestrial.
• The body is elongated with numerous segments.
• The head is provided with antennae, two pairs of jaws, and a pair of
simple eyes.
• They contain numerous legs.
• A pair of mandibles is present inside the mouth.
• They respire by trachea and excretion occurs by Malpighian tubules.
• Eg., Julus, Scolopendra
• The subphylum Myriapoda is divided into the following classes:
 Chilopoda
 Diplopoda
 Pauropoda
 Symphyla

10. HEXAPODA
• They are mostly terrestrial.
• The body is differentiated into head, thorax, and abdomen.
• The thorax is divided into three segments.
• The abdomen has 7-11 segments.
• They have three pair of appendages.
• It has a pair of compound eyes
• They respire through gills and trachea.
• Malpighian tubules are the excretory organ.
• Development is indirect, and the larval stage is present.
• Eg., Tabernus, Mosquitoes, Ants.
• The subphylum Hexapoda is divided into two classes:
 Insecta
 Entognatha

12. CHELICERATA
• They are mostly found on land.
• The body is differentiated into cephalothorax and abdomen.
• Antennae are absent.
• The abdomen is divided into 13 segments.
• It has four pairs of interior appendages.
• They respire through trachea or gills.
• The Malpighian tubules help in excretion.
• Eg., Aramea, Limulus
• The subphylum Chelicerata is divided into the following
classes:
 Arachnida
 Merostomata
 Pycnogonida

14. ONYCOPHORA
• These are small-
sized, terrestrial
arthropods.
• The body is divided
into segments.
• Excretion occurs
through nephridia.
• They respire
through the
trachea.
• Eg., Paripatus

15. TRILOBITOMORPHA
• These are primitive arthropods
and are extinct.
• They were found in abundance
during the Paleozoic era.
• The body was divided into
three lobes- one median and
two lateral lobes.
• Head bore a pair of compound
eyes and a pair of antennae.
• There was no structural
differentiation of the body
parts.
• The body was divided into
head, thorax and pygidium.
• Appendages are biramous.
• The subphylum had only one
class- Trilobita

16. METAMERISM
• Metamerism in arthropods refers to the
segmentation of the body into a series of repeating,
similar body segments known as metameres or
somites. This segmentation is a distinctive
characteristic of arthropods.
• Metamerism of arthropods is most evident
externally because the arthropod body is often
composed of a series of similar segments, each
bearing a pair of appendages.
• Internally, however, septa do not divide the body
cavity of an arthropod, and most organ systems are
not metamerically arranged.

17. ADVANTAGES OF
METAMERISM
• Segment specialization for specific functions
• Efficient, coordinated locomotion through
independent segment movement
• Flexibility and adaptation to diverse environments
• Supports development of complex body shapes
and sizes
• Segmental nervous system enables faster and
localized control of movements
• Facilitates controlled growth during molting cycles

18. TAGMATIZATION
• Metamerism permits the specialization of
regions of the body for specific functions.
This regional specialization is called
tagmatization.
• In arthropods, body regions, called tagmata
are specialized for feeding and sensory
perception, locomotion, and visceral
functions.

19. EXOSKELETON
• An external, jointed skeleton,
called an exoskeleton or
cuticle, encloses arthropods.
• It provides structural support
and protection.
• It provides impermeable
surfaces for the prevention of
water loss
• It provides a system of levers
for muscle attachment and
movement.
• The exoskeleton covers all
body surfaces and
invaginations of the body wall
• It is nonliving.
• Secreted by a single layer of
epidermal cells.

21. METAMORPHOSIS
• Reduction of competition between adults and
immature stages because of metamorphosis.
• Metamorphosis is a radical change in body form
and physiology as an immature stage, usually
called a larva, becomes an adult.
• The evolution of arthropods has resulted in an
increasing divergence of body forms, behaviors,
and habitats between immature and adult stages.
Example:
 The caterpillar that feeds on leafy vegetation
eventually develops into a nectarfeeding adult
butterfly or moth.

23. OVERVIEW
We have
discussed:
What are
arthropods?
Blueprint for
success
Classification
Metamerism &
Tagmetization
Exoskeleton
Metamorphosis