1. SUBPHYLUM CHELICERATA
AATHROPODA
SUBPHYLUM
CHELICERATA

2. Defining Characteristics
chelicerates have segmented bodies with jointed limbs, all covered in a cuticle made of chitin and proteins
chelicerate bauplan consists of two tagmata, the cephalothorax and the abdomen, except that mites have lost a visible division between these sections
Chelicerate are the only appendages that appear before the mouth

3. Defining Characteristics
has the open circulatory system typical of the arthropods, in which a tube-like heart pumps blood through the hemocoel, which is the major bod cavity
Marine chelicerates have gills, while the air-breathing forms generally have both book lungs and trachea
Absence of antennae
Marine species are horseshoe crabs, sea spiders , & mites s

4. SUBPHYLUM CHELICERATA
Class Merostomata
Class Pycnogonida
Class Arachnida

5. Class Merostomata Defining characteristics:
-Appendages on the abdomen are flatted and modified for gas exchange as “book gills”.
-Terminal portion of body drawn out into an elongated site.
Only four living species: the horseshoe crabs
The cephalothorax & abdomen are covered by a hard non-jointed carapace.

6. Class Merostomata

9. REPRODUCTION
Unusual in arthropods, it has gonochoric and have true external fertization
In male gonadal network is formed.
- duct
- testes being attached as small alveoli.
In female
- ovary forms all the branches.

10. CLASS PYCNOGONIDA

11. Class PYCNOGONIDA Defining characteristics:
- Body is not divided into distinct regions.
- Unique proboscis at anterior end, with an
opening at its tip.
- Includes the sea spiders, several of which
are common in our area.
- Feed on soft bodied invertebrates,
hydroids, bryozoans colonies & sponges.

12. Sea Spiders
Have a long proboscis for feeding & a digestive tract with gonads extending into walking legs.
Difficult to discern the cephalothorax & abdomen
Anterior appendages may bear cheliceras that group pieces food.
Ovigers-structures used by makes to carry eggs on body
When eggs are mature they are deposited in a hydroid colony

13. CLASS ARACHNIDA They have paired, jointed appendages
(parts that are attached to the main body)
Present of hardened exoskeleton
( exo means "outer")
Segmented (divided into parts) body, and
a well-developed head.
Their body consists of two main parts: a
fused head and thorax, and an abdomen

14. CLASS ARACHNIDA

16. CLASS ARACHNIDA They have paired, jointed appendages
(parts that are attached to the main body)
Present of hardened exoskeleton
( exo means "outer")
Segmented (divided into parts) body, and
a well-developed head.
Their body consists of two main parts: a
fused head and thorax, and an abdomen

17. Most arachnids live on land
They breathe by means of
book lungs (so called because their thin membranes are arranged like the pages of a book)
by tracheae (small tubes that distribute air from the outside throughout the body)
or both.