Insects are a diverse group of organisms that belong to the phylum Arthropoda and class Insecta. They are characterized by their three-part bodies (head, thorax, and abdomen), six legs, compound eyes, and exoskeletons made of chitin. Insects are the most numerous and varied group of animals on Earth, found in almost every habitat except the deepest oceans.
- Insects belong to the class Insecta within the phylum Arthropoda.
- They have a three-part body structure: head, thorax, and abdomen.
- Insects possess six legs and an exoskeleton made of chitin.
Body Segmentation
Insects have a body divided into three main segments: the head, thorax, and abdomen. The head houses the sensory and feeding structures, including eyes, antennae, and mouthparts. The thorax is responsible for locomotion and has three pairs of legs and, in most cases, two pairs of wings. The abdomen contains vital organs for digestion, reproduction, and excretion.
- Head: Contains sensory structures and mouthparts.
- Thorax: Muscular region with legs and wings (in most insects).
- Abdomen: Contains internal organs related to digestion and reproduction.
Exoskeleton
Insects have an exoskeleton made of chitin, which provides structural support and protection. This hard outer covering prevents water loss, making insects well-suited for terrestrial environments. The exoskeleton is segmented, allowing flexibility and movement at the joints. Molting, or ecdysis, is the process through which insects shed their exoskeleton to grow.
- Made of chitin: Provides strength and protection.
- Prevents water loss: Essential for survival in dry environments.
- Molting: Insects must shed their exoskeleton to grow.
Metamorphosis
Metamorphosis is a biological process in insects that involves significant change in form and function from larval stages to adult stages. There are two main types of metamorphosis: complete and incomplete. Complete metamorphosis involves four stages—egg, larva, pupa, and adult—while incomplete metamorphosis has three stages—egg, nymph, and adult. This process allows insects to exploit different ecological niches at various life stages.
- Complete metamorphosis: Egg, larva, pupa, adult.
- Incomplete metamorphosis: Egg, nymph, adult.
- Allows transition between life stages with different forms and functions.
Respiration
Insects breathe through a unique system of tracheae—small tubes that deliver oxygen directly to their tissues. Air enters the insect’s body through small openings called spiracles, located on the sides of the thorax and abdomen. This efficient system allows for rapid oxygen delivery, meeting the high metabolic demands of flying insects.
- Tracheae: Network of tubes that transport oxygen.
- Spiracles: Small openings for air intake.
- Directs oxygen to tissues, bypassing the circulatory system.