Question

There are three animal phyla that include “worm” in their common names. Why aren’t all worms placed into one phylum? What is different about each group of organisms that requires us to classify them into multiple phyla? Provide examples.

Answer 1

Answer: Flatworms, Roundworms and Segmented worms

Explanation:

These are not all placed in a phyla because the degree of developmental and morphological similarity is low.

The flatworms also known as platyhelminthes do not have coelom, no respiratory system or a circulatory system. An example is the tapeworm.

The roundworms also known as nematodes are slightly more complex than the flatworms in that they have a pseudocoelom and they are bilaterally symmetrical. An example is Ascaris lumbricoides.

The segmented worms are the most complex of them in that they have a true coelom, a circulatory system found in each segment and a digestive system. An example is the earthworm.

Answer 2

Answer: Flatworms, Roundworms and Segmented worms

Explanation:

These are not all placed in a phyla because the degree of developmental and morphological similarity is low.

The flatworms also known as platyhelminthes do not have coelom, no respiratory system or a circulatory system. An example is the tapeworm.

The roundworms also known as nematodes are slightly more complex than the flatworms in that they have a pseudocoelom and they are bilaterally symmetrical. An example is Ascaris lumbricoides.

The segmented worms are the most complex of them in that they have a true coelom, a circulatory system found in each segment and a digestive system. An example is the earthworm.