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| Arachnids | ||||||
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Acarina Amblypygi Araneae Opiliones Palpigradi Pseudoscorpionida Ricinulei Schizomida Scorpiones Solifugae Uropygi Parasitiformes Sarcoptiformes Trombidiformes Ref: ITIS 82708 2002-09-18 |
The arachnids, Arachnida, are a class of invertebrate animals in the subphylum Chelicerata. They are chiefly terrestrial arthropods, some 65,000 to 73,000 species including the spiders, scorpions, harvestmen, ticks, and mites. The arachnids are easily distinguished from the insects by the fact that they have 8 legs instead of 6. The pedipalpi (leg-like mouthparts) of some species has instead been adapted for sensory, prey capture or reproductive functions. In solpugids the palpi are quite leg-like and make solpugids appear to have ten legs. Larval mites have only sex legs: they grow their forth pair when the molt into nymphs.
Arachnids are mostly carnivorous, feeding on the pre-digested body of insects and other small animals. Many are venomous - they secrete poison from specialized glands to kill prey or enemies. Others are parasites, some of which are carriers of disease. Arachnids usually lay eggs, which hatch into immature adults.
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