How do crustaceans differ from arachnids?
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*
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Crustaceans differ from arachnids primarily in their body structure and habitat. Crustaceans typically have two pairs of antennae, biramous (branched) appendages, and a carapace covering their cephalothorax. They usually live in aquatic environments. Arachnids, on the other hand, have four pairs of legs, uniramous (unbranched) appendages, and lack antennae. They predominantly inhabit terrestrial environments.
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When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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