Arachnids are a class of joint-legged invertebrate animals, in the subphylum Chelicerata. They are characterized by having two body regions, a cephalothorax in front and an abdomen behind, and four pairs of legs that are jointed and used for walking. Arachnids include, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders, and vinegaroons.
Here are some key characteristics of arachnids:
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Body: Arachnids have two body regions, a cephalothorax and an abdomen. The cephalothorax contains the head and thorax, while the abdomen contains the reproductive organs and digestive system.
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Legs: All arachnids have eight legs, and unlike insects, they dont have antennae. The frontmost pair of legs in some species has converted to a sensory function, while in other species, different appendages can grow large enough to take on the appearance of extra pairs of legs.
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Appendages: Arachnids have 6 pairs of appendages: 4 pairs of legs and 2 pairs of mouthpart appendages, the first are called chelicerae. The second pair of mouthpart appendages are called pedipalps.
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Eating habits: Most arachnids can only eat liquid food, not solid food, so they squirt digestive chemicals into their prey and suck out the juice. Arachnids are predators on insects and other invertebrates, except for many mites, which are parasitic.
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Habitat: Almost all extant arachnids are terrestrial, living mainly on land. However, some inhabit freshwater environments and, with the exception of the pelagic zone, marine environments as well.
Arachnids are part of a larger group called arthropods, which also includes insects, myriapods, and crustaceans. All arthropods have an exoskeleton and legs that are jointed.
