Simplify the following text for a Grade 16 native English-speaking person.
Original: Exoskeletons contain rigid and resistant components that fulfil a set of functional roles including protection , excretion , sensing , support , feeding and ( for terrestrial organisms ) acting as a barrier against desiccation .
Simplified: Exoskeletons contain rigid and resistant components that fulfil a set of functional roles including protection , excretion , sensing , support , feeding and acting as a barrier against desiccation in terrestrial organisms .