Question 7

Earthworm is an invertebrate organism.

An earthworm is classified as an invertebrate because it lacks a backbone, which is a defining characteristic of invertebrate species. In contrast to vertebrates, earthworms belong to a diverse group of animals that do not possess a spinal column.

A) Dog

A dog is a vertebrate, as it has a backbone and is classified under the phylum Chordata. This option is incorrect because dogs have a skeletal structure that includes a spinal column, distinguishing them from invertebrates.

B) Fish

Fish are also vertebrates, characterized by having a backbone and a well-developed skeletal system. Therefore, this option is incorrect as fish do not fall under the category of invertebrates.

C) Snake

Snakes are reptiles and, like dogs and fish, they are vertebrates with backbones. This option is incorrect as it does not represent an invertebrate organism.

D) Earthworm

Earthworms are indeed invertebrates, belonging to the phylum Annelida. They lack a backbone and are important members of the soil ecosystem, contributing to soil aeration and nutrient cycling, making this option the correct choice.

Conclusion

The earthworm is definitively the correct answer as it exemplifies the characteristics of invertebrates with its lack of a backbone. In contrast, the other options—dog, fish, and snake—are all vertebrates, having skeletal structures that include a spinal column. This distinction is fundamental in the classification of organisms.