Insects and People: The Insect Exoskeleton

exoskeleton

suit of armor for a bug/insect

Is an exoskeleton tough or flexible?

It could be hard and thick, or thin and flexible

Is an exoskeleton heavy or light?

It could be as tough as nails are as light as a feather.

What do the qualities of an exoskeleton depend on?

Life stage, body part, or function

Basement membrane

first layer of exoskeleton, separates the inside from the outside

Epidermis

second layer of exoskeleton, layer of cells determines cuticle characteristics

Cuticle

Third layer of exoskeleton, contains 3 layers: endocuticle, exocuticle, and epicuticle

Endocuticle

bottom layer of cuticle, soft and flexible, made of protein and chitin.

Exocuticle

middle layer of cuticle, hard and rigid, tanned, made of protein + chitin + phenolics which makes sclerotin.

Epicuticle

top layer of cuticle, waterproof, made of protein + wax + cement.

Resilin

rubbery protein found on hinges and leaves

Spine

the most rigid part of the cuticle, 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)

Tricoghen cell

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

Ecdysozoa

a group of insects that molt.

Chitin

the most abundant polysaccharide in nature, makes up 25- 50 % of an insects entire weight.

What are the advantages of a tough outer skeleton?

Great protection. Waterproof, support the body weight well. Tough as nails but as light as a feather.

What are the disadvantages of exoskeletons?

Waterproof, not flexible, must be shed to grow

What's the most abundant biogenic organic polymer (polysaccharide) on earth?

chitin