Phylum Arthropoda presentation

1. PHYLUM
ARTHROPODA
Lecture-9

2. General Characteristics
• Segmented
• Jointed appendages
• Hard external skeleton
• 3 parts-head, thorax, abdomen (arachnids exception)
• Exoskeleton-hard, external skeleton made of chitin
• Molting- shed old exoskeleton and secrete a larger one, very vulnerable after molting
• Complete digestive tract ( mandible -chewing or proboscis - sucking) with a dorsal heart and a
ventral nervous system

3. • Respiration through gills, trachea, book lungs or
body surface
• Sensory organs include antennae and hairs, simple
and compound eye
• Reproduces (mostly sexually), one to several larval
stage
• The muscle system is more or less assisted by
hydraulics originated from the blood pressure
created by the heart
• Respiration through gills, trachea, book lungs or
body surface
• With open circulatory system. Haemolymph that
contains haemocyanin , a copper-based oxygen-
carrying protein
General Characteristics

4. Distribution and Abundance
Arthropods are found in almost all of the habitats that cover the Earth’s surface, even in your
own room!

5. Importance
• The larger crustaceans- shrimps, lobsters, and crabs- are used as food throughout the world.
• Although many species of insects and mites attack food crops and timber, arthropods are of
enormous benefit to human agriculture.
• The stings and bites of arthropods may be irritating or painful, but very few inject dangerous
toxins.
• Medically, arthropods are more significant as carriers of diseases.

6. Arthropod relation to us..
Medical Arthropod:
• Arthropods related with human health.
Medical Arthropodology:
• Morphology, taxonomy, life cycle, ecology, transmission of the diseases, control measures.
Examples:
• Flea Bubonic Plague
• Soft tick Q fever
• Mosquito Malaria

7. Classification

8. Subphylum Trilobitomorpha
General characters
• Primitive arthropod
• Extinct form
• Abundant during Paleozoic era
• Body is divided into three lobes, hence the name trilobitomorpha
• Body division; head, abdomen and pygidium
• Head bears a pair of antenna and eye
• Eyes were compound
• Appendages biramous
• Structural differentiation of body parts absent
Classes
Trilobita (extinct)

9. Subphylum Chelicerata
General characters
• Presence of chelicerae (modified anterior most appendages)
• Cephalothorax or prosoma with anterior six segments
• Abdomen or opisthosoma with thirteen segments
• Abdomen is divided into mesosoma and metasoma
• Antennae completely absent
Classes
• Arachnida; spiders and scorpions
• Merostomata; Horseshoe crabs
• Pycnogonida; Sea spiders

10. General characteristics
• Include millipedes and centipedes
• All are terrestrial arthropods
• Usually contain many legs
• Single pair of antenna
• Eyes simple
• Mouthparts lie on the underside of head
• Upper lip of mouth with epistome and labrum
• Lower lip with pair of maxillae
• A pair of mandibles present
• Breathe through spiracles that connect tracheal system similar to insects
• Excretion through malpighian tubules
Subphylum Myriapoda

11. Classes
This subphylum include four classes
• Chilopoda; centipedes
• Diplopoda; millipedes
• Pauropoda;
• Symphyla;
Subphylum Myriapoda

12. Subphylum Crustacea
General characteristics
• Usually marine aquatic arthropods
• Head and thorax fused to form cephalothorax
• Cephalothorax usually covered by single large carapace
• Eyes are compound
• Two pairs of antenna, five pairs of cephalic appendages
• Respiration through gills
• Excretion by green glands or antennal glands
• Paired gonopores
• Development is usually indirect
• Larval form is called nauplius

13. Classes
This subphylum include six classes
a) Branchiopoda; Brine shrimps
b) Remipedia; Bind crustaceans
c) Cephalocarida; Horseshoe shrimps
d) Maxillopoda; Barnacles
e) Ostracoda; Seed shrimps
f) Malacostraca; lobsters, crabs, shrimps
Subphylum Crustacea
a
b
c
d
e
f

14. Subphylum Hexapoda
General characteristics
• A large taxa include insects and a group of wingless arthropods
• Body plan; three parts, head, thorax and abdomen
• Head with six segments
• Thorax with three pairs of jointed legs (hence the name hexapoda)
• Head contains a presegmental acron which bears compound eye
• Head segments are closely fused
• Antennae present
• Mouth lie between the 4th and 5th segment of head
• Thorax with three segments, each bears a pair of legs

15. General characteristics
• Abdomen usually with 11 segments
• Abdomen appendages are absent or extremely reduced
• Abdomen contain most of the internal systems such as respiratory, excretory and reproductive
system
• Respiration through tracheal system
• Excretion through malpighian tubules
• Development always indirect
• Larval stages present which undergo metamorphosis
Subphylum Hexapoda

16. Classes
Hexapoda is divided into two classes
• Insecta; winged insects
• Entognatha; wingless insects
Subphylum Hexapoda