Which one of the following groups of animals is bilaterally symmetrical and triploblastic?
- Aschelminthes (round worms)
- Ctenophores
- Sponges
- Coelenterates (cnidarians)
Answer
(1) Aschelminthes (round worms)
Solution
As per NCERT, aschelminthes (roundworms) are bilaterally symmetrical, triploblastic and pseudocoelomate animals.
∵ Ctenophores and coelenterates are radially symmetrical and diploblastic, and sponges are asymmetrical with a cellular level of organisation,
∴ only Aschelminthes are bilaterally symmetrical and triploblastic.
Answer: (1)