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Sunday 10 March 2013

Classification of Phylum Arthropoda


Phylum :- Arthropoda



Characters :- 

(i) A pair of externally jointed appendages is usually present in each segment.

(ii) Body is externally covered by thick, tough & chitinous cuticle, forming the exoskeleton.



SubPhylum :- Crustacea


Characters :- 

(i) Head bears five pairs of appendages which comprises of two pairs of antennae & two pairs of maxilla.

(ii) Respiration usually through gills.



Class :- Branchiopoda


Characters :- 

(i) Trunk appendages are flattened leaf like structure.

(ii) Coxa is provided with a flattened epipod.



Examples :- Triopes(tadpole shrimp); Daphnia; Artemia;



Fig :- Triopes
Fig :- Daphnia
Fig :- Artemia










Class :- Ciripedia


Characters :-

(i) Body enclosed within a bivalve carapace.

(ii) Body is poorly segmented & most lack abdomen.


Examples :- Lepas; Balanus; Sacculina;


Fig :- Balanus
Fig :- Lepas


Fig :- Sacculina





















Class :- Malacostraca



Characters :-

(i) Body comprises of head, an eight segmented thorax & six segmented abdomen.

(ii) The posterior thoracic limbs being walking legs, the 1st five pairs of abdominal ones forming swimming organs.


Examples :- Squilla; Hippa; Macrobrachium(prawn); Cancer;

Fig :- Squilla

Fig :- Macrobrachium














SubPhylum :- Uniramia



Characters :-

(i) Appendages are uniramous




Class :- Diplopoda



Characters :- 

(i) Presence of double trunk segments, which are either cylindrical or somewhat flattened.

(ii) Presence of calcified exoskeleton.



Example :- Julus


Fig :- Julus












Class :- Insecta



Characters :- 

(i) Head formed by the fusion of 6 segments, typically bears a single pairs of antennae & two pairs of maxillae.

(ii) The trunk in insects subdevided into three segmented thorax & an abdomen of 11 segments without walking legs.



Examples :- Lepisma(silver fish); Periplaneta; Carausias(stick insect);Bombyx; Anopheles;




Fig :- Lepisma

Fig :- Periplaneta



Bombyx
Fig :- Anopheles











SubPhylum :- Chelicerata



Characters :- 

(i) Body divided into an anterior cephalothorax or prosoma, which wholly or partially covered by a dorsal carapace  & a posterior abdomen or opsthosoma.

(ii) Lack of antennae.



Class :- Merostomata



Characters :- 

(i) A prominent spike like caudal spine or telson is present at the end of the body.

(ii) Prosoma is covered by a large, horse shoe shaped carapace.


  
Example :- Limulus


Fig :- Limulus












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