Question

Animals showing metameric segmentation are
A. Porifera
B. Annelids
C. Tapeworms
D. Nemathelminthes

Answer 1

Hint: Metameric segments means the repetition of organs or tissues at intervals and they have linear series of body segments, for example, metameric segmentation is seen in earthworms.

Complete answer:
Let's start with option A which is Porifera. In this phylum, there are around 5000 living sponge species. All poriferans are aquatic and mostly marine. They are sessile and sedentary. These are multicellular organisms which means they have more than one cell and they have cellular level body of organisation. There are no distinct tissues and organs. They do not show metameric segmentation and thus this option is incorrect and it gets eliminated.
Moving to option B which is Annelids. Annelids are also known as ringed worms and they have long and segmented bodies. They are bilaterally symmetrical and since their bodies are made up of segments, they exhibit metameric segmentation. Since there is repetition of organs in annelids. Therefore, this option is the correct one.
Moving to option C which is Tapeworms. These flat and segmented worms are found in the intestines of animals and it causes infection in people when they eat undercooked meat from animals which are infected with these parasites. They do not show metameric segmentation and therefore this cannot be the correct option and it gets eliminated.
Last option is D which is Nemathelminthes. These are called roundworms or thread worms. They are unsegmented and their body is covered by a body wall having cuticles and epidermis. They do not show metameric segmentation and hence it cannot be the correct option, it gets eliminated.

Thus, the correct answer is option C which is Annelids.

Note: Metameric segmentations are found in annelids like in case of earthworms, there are repeated organs and their body is made up of segments which are bilaterally asymmetrical. This segmentation divides the body into a linear series of similar parts or you can say similar segments and these segments are also called metameres.