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?
Insects belong to the phylum Arthropoda, a defining characteristic of which is the presence of jointed legs. Earthworms belong to the phylum Annelida and do not have jointed legs; their locomotion relies on bristles (setae) and muscular contractions.
Jointed legs are a characteristic feature of arthropods, including insects, arachnids, crustaceans, etc., which differentiates them from annelids like earthworms.
While both insects and earthworms have segmented bodies and are bilaterally symmetrical, these characteristics are common to many animal groups and do not uniquely identify an insect versus an earthworm. Insect bodies are typically divided into three distinct segments (head, thorax, abdomen), whereas earthworm segmentation is more uniform rings along the body.