Question

Earthworm belongs to
A. Mollusca
B. Porifera
C. Annelida
D. Arthropoda

Answer 1

Hint: A terrestrial invertebrate which belongs to the order opisthopora is called an earthworm. The body plan of earthworms is of segmented type. An organ called nephridia is a tube coiled like structure which performs the function of filtering waste out of the body.

Complete answer: The division of an animal or plant body into a series of repetitive segments is called segmentation of the body. The segmented body is a characteristic feature of Arthropoda, Chordata, and Annelida. Segmentation of the body plan allows the development and free movement of certain parts of the body. The earthworm is an annelid that is made up of 100-150 segments. Each segment of the earthworm has a pair of nephridia which is used for excretion and filtration. An organ called nephridia is a tube coiled like structure which performs the function of filtering waste out of the body. They are mainly grouped in pairs and are present throughout the body. Three types of nephridia are seen on the earthworm’s body. Depending upon the location it is situated they are named pharyngeal nephridia, integumentary nephridia, and septal nephridia. Arthropoda is a phylum of invertebrates that show the presence of an exoskeleton, paired jointed appendages, and segmented body. Many of the insects, myriapods, arachnids, and crustaceans belong to the phylum Arthropoda. Mollusca is a phylum which consists of soft-bodied invertebrates that are partly or wholly enclosed in a calcium carbonate shell secreted by a soft mantle covering the body. Porifera are the pore bearing multicellular organisms. Therefore, earthworms belong to Annelida.

So, option C is the correct option.
Note: Annelids are also called segmented worms or ringed worms. Other examples of annelids are species of leeches and ragworms. Annelids are triploblastic, coelomate, and bilaterally symmetrical invertebrate organisms. Earthworms play an important role in the enriching and aeration of the soil.