Question

The triploblastic animal who bears mesoderm but lacks mesoderm-lined true body cavity is
a) Planaria
b) Pheretima
c) Nereis
d) Pila​

Answer 1

Explanation:

hi you refer to attached this iamge

Answer 2

Planaria is the triploblastic animal that bears mesoderm but lacks a mesoderm-lined true body cavity.

• Triploblastic animals are the animals that consist of mesoderm, a growing embryo that has a 3rd germinal layer.
• This germinal layer lies between the endoderm and the ectoderm. Triploblastic animals include Platyhelminthes that have tissues which is differentiated into 3 different layers of cell and are known also known as flatworms.
• Planaria involves three different layers of cells and have mesoderm. But this lined mesoderm does not have a true body cavity.

Hence, a is the correct option.