ENT201 - Exam 1 - Eyes, Ears, Nose, and Throat

Insect body segment organization

20 total segments in 3 body regions

Insect head structure

• A hard capsule formed by the fusion of 6 segments

• Acts as the sensory and feeding center

• Insect mouth parts: Appendages modified to form mouthparts

Compound eye structure

• A mosaic of hexagonal subunits or facets aligned with light-sensing cells

• Some can see colors —> violet, blue, green, and yellow, but cannot see red

Insect motion detection speed

Insects detect movement significantly faster than human eyes can

Ocelli

• Simple eyes consisting of a single facet

• Senses light and some movement

Plumose antennae function

Feather-like antennae designed to maximize surface area to detect female pheromones

Chewing mouthparts layout

Original insect layout: labrum, 2 mandibles, maxillae, labium, and hypopharynx

Labrum

• The top lip/front section of the mouth

• Prevents food from falling out while eating

Mandibles

• The hardest part of the exoskeleton is located behind the labrum

• Wearing it out causes starvation

Hypopharynx

The tongue-like structure tucked inside the insect’s mouth

Maxillae

• Paired structures behind the hypopharynx

• Recognized as the most ‘leg-like’ of mouthparts

Labium

The bottom lip/floor of the insect’s mouth

Piercing-sucking mouthparts

• Mouthparts that puncture tissues

• Extract liquids

• Common in mosquitoes

Sponging mouthparts

• Mouthparts that soak up liquids

• Common in house flies

Chewing-lapping mouthparts

• Mouthparts suited for both liquid nectar and solid pollen

• Common in bees

Siphoning mouthparts

• Tube-like mouthparts used to draw up uncontained liquids

• Common in butterflies and moths

Vestigial mouthparts in adults

• Non-functional or absent mouthparts

• Certain moths and mayflies

Xanthopan morganii flower pollinator

• A specialized moth species with a long proboscis adapted for this specific flower