Rupa and Sachin observed an animal in their school garden. Rupa called it an insect while Sachin identified it as an earthworm. Which one of the following characteristics confirms that it is an insect ?

The presence of jointed legs is the primary characteristic that confirms the animal is an insect rather than an earthworm. Insects belong to the phylum Arthropoda, which is defined by having jointed appendages and an exoskeleton [1]. Specifically, insects are characterized by having six legs and three distinct body parts: the head, thorax, and abdomen [1]. In contrast, earthworms belong to the phylum Annelida, which consists of segmented worms that lack limbs or jointed legs [2]. While both insects and earthworms exhibit body segmentation and bilateral symmetry, the presence of legs is a distinguishing feature of insects [3]. Earthworms are typically cylindrical and move without legs, whereas insects are well-known invertebrates with jointed legs [2]. Therefore, observing jointed legs would definitively identify the animal as an insect in this scenario.

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 9: Indian Biodiversity Diverse Landscape > ENVIRONMENT > p. 156
2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 9: Indian Biodiversity Diverse Landscape > Annelide > p. 155
3. [3] https://www.elearn.gov.pk/onlinepdf/science/5science/chapter1/files/basic-html/page10.html