Question

Which of the following is the common characteristic found in all the worms?

• A. Endo-parasitism
• B. Free-living
• C. Triploblastic
• D. Metameric segmentation

Answer 1

The correct option is C Triploblastic

Worms are found in three phyla-Platyhelminthes, Aschelminthes and Annelida. For example,
Platyhelminthes : Tapeworms and Planaria
Aschelminthes : Wuchereria and Ascaris
Annelida : Pheretima (Earthworm) and Nereis
Organisms in all these three phyla have three germ layers- ectoderm, mesoderm and endoderm and are, hence, triploblastic.

Tapeworm, Planaria, Wuchereria, Ascaris are endo-parasites but Pheretima is not a parasite. It is a free-living organism. All the endo-parasites live in the bodies of their hosts.

Metameric segmentation of worms is only seen in the organisms of phylum Annelida.