How do crustaceans differ from arachnids?
1 Answer
Crustaceans and Arachnida are classes of Phylum Arthopoda
Arthropoda : Animals with jointed legs .
Largest phylum .
CRUSTACEA :
- Habitat - Aquatic
- Body - Differentiated into cephalothorax (head & thorax are fused) & abdomen. + dorsal cuticular plate Carapace
-
Appendages - 2 pair of antennae, one pair of mandible and generally two pair of maxillae in head. As many as 5 pair of walking legs could be present in thorax, smaller legs for swimming present in abdomen. All appendages in crustacea are biramous**
-
Antennae - 2 pairs
- Respiration -Since it is acquatic, respiration takes place with the help of gills
- Excretion - Antennary gland or Green gland
Examples *Crabs , prawns , lobsters , shrimps , cyclops *
ARACHNIDA :
Habitat -Terrestial
-
Body - Body is differentiated into cephalothoroax & abdomen
(same as crustaceans but carapace is absent ). -
Appendages - 6 paired 1 pair Chelicereae , 2 pairs Pedipalp & rest 4 pairs walking legs .**
-
Antennae - Absent
-
Respiration - Since it is terrestrial, respiration takes place through book lungs ( appear as an open book )
-
Excretion - Coxal gland
*Examples - Spiders , Scorpians e.t.c*
