Insects and People: The Insect Exoskeleton

The Exoskeleton

The exoskeleton is like an ==insect’s suit of armor.==

  • It’s ==tougher than nails==, but as ==light== as a feather.
  • It may be ==hard and thick, or thin and flexible.==
    • Depends on the life stage, body part, function, etc.
    • But once the exoskeleton is hard, it does not stretch any further.
    • It covers the entire outer body surface, as well as some internal surfaces.

Places and parts

  1. ==Basement membrane==
    • the first layer of the exoskeleton
    • very thin
    • separates inside from the outside
  2. ==Epidermis==
    • produces the endocuticle and the exocuticle
    • layer of cells determines the characteristics of the cuticle
  3. ==The cuticle==
    • Three main layers
      • Endocuticle: bottom layer, soft and flexible, made of protein and chitin
      • Exocuticle: middle layer, hard and rigid, tanned, made of protein + chitin + phenolics which makes sclerotin
      • Epicuticle: top layer, waterproof, made of protein + wax + cement
  4. ==Resilin==
    • A rubbery protein that is on hinges and levers
  5. ==Hairs, warts, bumps, spines, spurs, seta, and other outgrowths (and ingrowths)==
    • Spine: the most rigid part of the exoskeleton, shed during molting
    • Spur: the defensive method of the exoskeleton, mostly rigid, shed during molting
    • Setae: a hair-like protrusion of exoskeleton that is the most flexible, and is not shed during molting, but it is easily regenerated when lost (these are grown from tricoghen cells)

What are some advantages of an exoskeleton?

  • Waterproof
  • Protection
  • Tough, but light
  • Supports the body weight well

What are some disadvantages of an exoskeleton?

  • Not flexible
  • Must be shed in order to grow
  • Waterproof (this quality can be both good and bad)

VOCABULARY

Tricoghen cell: forms the perforated part of the hair shaft and the stimulus-conducting system, consisting of the pore tubules.

Chitin: the most abundant polysaccharide in nature, makes up 25-50% of an insect’s entire weight.

Ecdysozoa: a group of insects that molt