arachnid (ərăk`nĭd), mainly terrestrial arthropod of the class Arachnida, including the spider spider, organism, mostly terrestrial, of the class Arachnida, order Araneae, with four pairs of legs and a two-part body consisting of a cephalothorax, or prosoma, and an unsegmented abdomen, or opisthosoma.
..... Click the link for more information. , scorpion scorpion, any arachnid of the order Scorpionida with a hollow poisonous stinger at the tip of the tail. Scorpions vary from about 1/2 in. to about 6 in. (1–15 cm) long; most are from 1 to 3 in. (2.5–7.6 cm) long.
..... Click the link for more information. , mite ticks, are all parasitic in at least one developmental stage; most parasitize mammals and birds although some have reptilian and amphibian hosts. Tick-borne diseases of livestock (e.g., babesiosis , anaplasmosis ) are of great economic significance.
..... Click the link for more information. and tick, harvestman harvestman, arachnid, often called daddy longlegs because of its eight long, slender legs. The harvestman has a rounded or oval body possessing glands that give off an acrid scent.
..... Click the link for more information. (daddy longlegs), and a few minor groups. The body is divided into a cephalothorax with six pairs of appendages, and an abdomen. The first two pairs of appendages are used to kill and crush prey (most arachnids being carnivorous); the remaining four pairs are walking legs. Arachnids have simple eyes and no antennae but are equipped with sensory bristles. Some respire with air tubes, but most possess primitive respiratory organs called book lungs book lung, terrestrial respiratory organ characteristic of arachnids such as scorpions and primitive spiders. Each book lung consists of hollow flat plates. Air bathes the outer surface of the plates and blood circulates within them, facilitating the exchange of
..... Click the link for more information. . Arachnids are classified in the phylum Chelicerata Chelicerata (kəlĭs'ərät`ə)
..... Click the link for more information. , class Arachnida.

arachnid

Any member of the class Arachnida, primarily carnivorous arthropods having a well-developed head, a hard external skeleton, and four pairs of walking legs. Spiders and scorpions have a segmented body, but daddy longlegs, ticks, and mites do not. Arachnids range in size from tiny mites (0.003 in. [0.08 mm] long) to the 8-in. (21-cm) black scorpion of Africa. As arachnids grow, they molt several times (see molting). Most are unable to digest food internally; instead, they inject their prey with digestive fluids and suck the liquefied remains. Arachnids are found worldwide in nearly every habitat. Most groups are free-living, but some mites and ticks are parasitic and can carry serious diseases of animals and humans. Venomous spiders and scorpions also may pose a danger to humans. However, most arachnids are harmless and prey on insect pests.

arachnid

any terrestrial chelicerate arthropod of the class Arachnida, characterized by simple eyes and four pairs of legs. The group includes the spiders, scorpions, ticks, mites, and harvestmen

arachnid (redirected from arachnidan)

arachnid

arachnid
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