Karthikeyan

Insects

Key Features

• Wings: Usually present (one or two pairs)

• Antennae: One pair

• Legs: Three pairs (6 legs) attached to the thorax

• Body regions: Head, thorax, abdomen

• Abdomen: No limbs

Adaptations for Land

• A waxy cuticle prevents:

  • Loss of water from the body

  • Entry of excess water

• This helps insects survive in hot, dry climates

• Because of this, insects have successfully colonised land

Arachnids

Examples

• Spiders

• Scorpions

• Mites

• Ticks

Body Structure

• Two body regions:

  • Cephalothorax (combined head + thorax)

  • Abdomen

• Legs: Four pairs (8 legs) attached to the cephalothorax

• Antennae: None

Special Structures

• Pedipalps (2 pairs):

  • One pair used in reproduction

  • One pair used to pierce prey and inject poison

• Eyes: Several simple eyes