Which arthropodans do possess bodies divided in only two distinct parts, namely prosoma/opisthosoma or cephalothorax/abdomen?

2 Answers
Dec 11, 2017

Crustacea and Arachnida .

Explanation:

The classes of arthropods mentioned above have their heads fused with thorax forming cephalothorax.

https://online.science.psu.edu/biol110_sandbox_8862
Lobster is a member of crustaceans.

https://takeyourbreathaway.weebly.com/arachnids.html

Hope it helps....

Dec 11, 2017

One is Arachnida, other is Crustacea. Please note horse shoe crab ( Limulus sp.) also has similar distinction.

Explanation:

Great question.

First thing first: body of arthropoda has three parts, head thorax and abdomen.

All three parts are distinct in class Insecta.

In Chilopoda, Diplopoda, Pauropoda, Symphyla, etc thorax and abdomen form a trunk: so there are head and trunk in the body.

When head fuses with thorax, it is either called prosoma as in case of Arachnida, or known as cephalothorax as in Crustacea.

  • In class Merostomata, Limulus is only living representative which also has prosoma. The abdomen is called opisthosoma.

https://st2.depositphotos.com/3413075/7512/i/950/depositphotos_75125831-stock-photo-horseshoe-crab-limulus.jpg
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  • In case of Crustacea, body is divided in cephalothorax and abdomen; cephalothorax remains dorsally covered by a single calcified exoskeletal element called carapace. Crustacea includes aquatic arthropods with two pair of antennae.

http://www.sciencewithmyrt.com/uploads/3/2/1/8/32187613/33-23-07-11-2-33-26_1_origjpeg

  • Most famous members of class Arachnida are scorpions and spiders. The body has prosoma (=head plus thorax) and opisthosoma (=abdomen).

http://i53.photobucket.com/albums/g78/wraithspirit/spider%20bits/DORSALVIEW-1jpg