phylum Arthropoda, characteristics, structure, systems and classes

1. Phylum Arthropoda
Prepared by
Sabreena

2. Phylum Arthropoda:
Arthros: jointed, Pods: feet
It is the largest phylum in
the animal kingdom, which
includes familiar forms
such as crabs, spider,
mites, millipedes and
centipedes.

3. General Characteristics
Habitat:
They can be found in all
types of habitat, show great
variety of adaptations.
Number:
About 84% of all known
species of animals are the
members of phylum
Arthropoda.

4. Body Structure:
 The body is segmented into three regions
head, thorax and abdomen, which are
attached to each other by cuticle.
 The body is covered by chitin.
 There are several pairs of appendages.
 They are triploblastic having jointed limbs.
 Body cavity is filled with blood which is white
in colour.
 They varies in structure some are worms like
and other are flying insects.

5. Exoskeleton:
 It is hardened and made of
chitin.
 In few species it is made of
calcium carbonate.
 It is non expandable as the
organism grows.
 They shed their skeleton so
that it can be replaced by new.
This process is called moulting.

7. 1 2 3
4 5 6

8. Digestive system:
Elementary canal has two opening, the mouth
and anus. Each part is modified for specific
function. They feed on small plants, plants
juices, animals etc

9. Excretory system:
It consists of Malpighian tubules which filter the
nitrogenous wastes and uric acid. Some aquatic
and terrestrial organisms have excretory organ
called nephridia.

10. Respiratory system:
Most terrestrial arthropods breath through
tracheal tubes that extend through out the body.
Air enters and leaves the body through openings
called spiracles. In aquatic respiration takes
place through gills.

11. Circulatory system:
Arthropods have an open circulatory system.
Blood flows in body cavity in the heart and
blood vessel. Blood is colourless and have
hemocyanin(copper) instead of
haemoglobin(iron).
Reproductive system:
Sexes are separate, the testes produce sperms
and ovaries produce eggs. Fertilization is mostly
internal.

12. Nervous system:
Highly developed and
consists of paired ganglia
connected to a ventral
double nerve cord. There is a
ganglion in each segment
from which nerves arise. A
pair of compound eye and
antennae form the sensory
organ.

14. Classification of phylum Arthropoda

15. Class Crustacea:
These are aquatic found in fresh and
marine water. The appendages are
modified for capturing food, walking,
swimming, respiration and
reproduction. Coelom is reduced and
haemocoel is present. Head has two pair
of antennae. Sexes are mostly separate.
Examples:
Daphnia, Cyclops, Crab, Lobsters,
Prawn and Wood louse.

16. Class insecta:
It is the largest group of animal kingdom. Insects
are found everywhere. . Body is divided into head,
thorax and abdomen. There is a pair of antennae
and two compound eyes on the head. The thorax is
divided into three segments. Each segment has a
pair of jointed legs. Thorax may be a one or two
pair of wings. Nervous system consists of a brain
and nerve cord. Sexes are separated.
Example:
Ants, Honey bee, Mosquito, Butterfly etc.

17. Class Arachnida
Body is divided into cephalon thorax and
abdomen. Cephalon thorax has a pair of
appendages called chelicerae with claws,
two pairs of pedipalp and four pairs of legs,
antennae and jaws are absent. The
respiratory structures are gills lungs and
book lungs. Excretion takes place through
Malpighian tubules. The sexes are separate.
Examples:
scorpions, spiders, mites etc.

18. Class myriapod:
The body is divided into large
number of segments. Each
segment has a pair of legs. On
the head, there is a pair of
antennae, pair of eyes.
Example:
centipede, millipede etc.

19. Importance:
 Arthropods play an important role in maintaining
the health of ecosystems
 Provide livelihoods and nutrition to human
communities
 Important indicators of environmental change
 Some arthropods break down dead plants and
animals and turn them into soil nutrients.
 Supplies the plants with the minerals and
nutrients necessary for life.