(Latin: a suffix used to form names of zoological groups, classes, and orders)
Many of the most important parasites and vectors of human and animal pathogens are included in this large assemblage.
More about Arthropoda
Along with the insects, crustaceans, centipedes, and millipedes; spiders are members of that group of animals without backbones referred to as the Arthropoda, literally the "jointed-limbed" animals.
Clearly they lack a backbone and instead have an external skeleton, called an exoskeleton, which has some similarities to a suit of armor; it is tough and fairly rigid and the muscles are attached to it internally.
Like the vertebrate skeleton, that of the arthopods is designed as a compromise between rigidity, to provide support and protection for the soft, delicate internal organs, and flexibility, to allow for ease of movement.
The color of the body can be yellowish-tan to dark-brown, with the paired claws often a contrasting color. They have two very long pedipalps, or pincers, which strongly resemble the scorpion's claws, but the pseudoscorpion's abdomen is short and rounded at the rear, rather than extending into a segmented tail and sting.
The movable part of the pincer contains a venom gland and duct; the poison is used to capture and immobilize their tiny prey. They do not bite.
To digest prey, they pour a mildly corrosive fluid over the prey, then ingest the liquefied remains.
They spin silk from a gland in their jaws to make disk-shaped cocoons for mating, molting, or enduring cold weather.