Question

The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of

(A) a body cavity.

(B) a complete digestive tract.

(C) mesoderm.

(D) tissues.

Short answer

(A) The option “a body cavity” is false.

(B) The option “a complete digestive tract” is false.

(C) The option “mesoderm” is false.

(D) The option “tissues” is true.

Step-by-step solution

Sponges

Sponges are organisms that are grouped under the phylum Porifera. These organisms are found in an aquatic environment with a body type that is not symmetrical. The body is diploblastic that is made up of two germ layers.

Explanation of option ‘(A)’

Sponges are organisms that lack any body cavity. These organisms are referred to as acoelomates. These organisms have surface pores on the body that enables the exchange of water through which feeding and excretion happen.

Thus, the body cavity cannot be used to differentiate sponges from other organisms.

Therefore, the given option is false.

Explanation of option ‘(B)’

Sponges are organisms that do not have specific body organs and organ systems. Due to this, these organisms consume food that is taken through the water bubbles. Then the collar cells digest the food particles.

Thus, the presence or absence of the digestive tract cannot be used to differentiate sponges from other organisms.

Therefore, the given option is false.

Explanation of option ‘(C)’

Sponges do not possess germ layers like other complex groups of animals. Therefore, due to the absence of the mesoderm essential for giving rise to organs of the body, they lack any internal organs.

Thus, the presence or absence of a germ layer cannot be used to differentiate sponges from other organisms.

Therefore, the given option is false.

Explanation of option ‘(D)’

Unlike other organisms that exhibit tissue level of organization, sponges do not exhibit tissue level of organization. These organisms lack body tissues, and hence this can be used as a distinguishing trait to differentiate between sponges and other animals.

Thus, the presence or absence of tissue can be used to differentiate sponges from other organisms.

Therefore, the given option is true.