Arachnids are predaceous, either actively hunting or patiently lying in wait for small animals such as insects. They have various structures that are geared to capturing prey. Some of these features are the segmented, stinging tail of scorpions and the abdominal spinnerets (that allow for the construction of insect traps, or webs) of spiders. Since they do not have the ability to masticate (chew) their food with their mouthparts, they are generally able only to feed on the fluids of their prey. After piercing the prey's body wall with their chelicerae, arachnids will either ingest the fluid contents or digest the tissues externally with enzyme-containing secretions that are ejected from the mid-gut (as with spiders) or the salivary glands (as with ticks and mites). A powerful suctorial pharynx draws the fluid up through the pre-oral food canal and delivers it into the mid-gut. Gaseous exchange occurs in a variety of ways. Respiratory gases may enter and leave the body through specialized structures (either lung-books or spiracles) or may diffuse through the cuticle (as in some mites and larval ticks).
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