Entomology Basics

Study Notes

Hexápodos (Hexapoda) is a subphylum of arthropods that includes insects and their closest relatives.
Entomology is the study of insects, including their behavior, ecology, evolution, and classification.
Hexápodos are a key focus of entomology due to their diversity and importance in ecosystems.

Hexápodos evolved from a common ancestor with crustaceans (Crustacea) around 400-450 million years ago.
The evolution of hexápodos is characterized by the development of:
- Three main body parts: head, thorax, and abdomen.
- Six legs (hexapodous) attached to the thorax.
- Wings (in most insects) that arise from the thorax.
Hexápodos have undergone significant evolutionary adaptations, such as the development of compound eyes and antennae.

Hexápodos have a three-part body consisting of:
1. Head: contains eyes, antennae, and mouthparts.
2. Thorax: contains wings and legs.
3. Abdomen: contains digestive organs and reproductive organs.
Insect body structure is characterized by:
- Exoskeleton: a hard outer covering that provides support and protection.
- Segmentation: the body is divided into repeating parts or segments.

Hexápodos are classified into several classes, including:
- Insecta (true insects): includes most familiar insects, such as beetles, flies, and bees.
- Entognatha (hidden-mouth insects): includes springtails and bristletails.
- Archaeognatha (ancient jaw insects): includes jumping bristletails.
Insect classification is based on characteristics such as:
- Body structure and morphology.
- Wing development and venation.
- Mouthpart structure and function.

Hexápodos exhibit a range of morphological adaptations, including:
- Body shape and size: varies greatly between species, from tiny fairyflies to large beetles.
- Leg structure: adapted for walking, running, jumping, or swimming.
- Wing shape and structure: adapted for flying, gliding, or other forms of locomotion.
- Sensory structures: such as compound eyes, ocelli, and antennae.