Spiders are air-breathing arthropods of the order Araneae, which have eight legs,
chelicerae with fangs generally able to inject
venom, and
spinnerets that extrude
silk. They are the largest order of
arachnids and rank seventh in total species diversity among all
orders of organisms, with more than 50,000 species recorded in 132
families. Anatomically, spiders (as with all arachnids) differ from other arthropods in that the usual body
segments are fused into two
tagmata, the
cephalothorax or prosoma, and the
opisthosoma, or abdomen, and joined by a small, cylindrical
pedicel. Unlike
insects, spiders do not have
antennae. Spiders are found on every continent except for
Antarctica, and have become established in nearly every land
habitat type. This adult male jumping spider (
Plexippus paykulli) was photographed in the US state of Florida.
Photograph credit: Spidereyes2020