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Basic arrangement of spider eyes, viewed from above. Most spiders have eight eyes, which tend to be arranged into two rows of four eyes on the head region. The eyes can be categorised by their location and are divided into the anterior median eyes (AME), anterior lateral eyes (ALE), posterior median eyes (PME), and posterior lateral eyes (PLE).
Spiders also have several adaptations that distinguish them from other arachnids. All spiders are capable of producing silk of various types, which many species use to build webs to ensnare prey. Most spiders possess venom, which is injected into prey (or defensively, when the spider feels threatened) through the fangs of the chelicerae. Male ...
Sparassids are eight-eyed spiders. The eyes appear in two largely forward-facing rows of four on the anterior aspect of the prosoma. Many species grow very large – in Laos, male giant huntsman spiders (Heteropoda maxima) attain a legspan of 25–30 centimetres (9.8–11.8 in).
[25] [26] The other pairs, called secondary eyes, are thought to be derived from the compound eyes of the ancestral chelicerates, but no longer have the separate facets typical of compound eyes. Unlike the principal eyes, in many spiders these secondary eyes detect light reflected from a reflective tapetum lucidum, and wolf spiders can be ...
However, the main eyes of spiders are pigment-cup ocelli that are capable of forming images, [45] and those of jumping spiders can rotate to track prey. [ 46 ] Compound eyes consist of fifteen to several thousand independent ommatidia , columns that are usually hexagonal in cross section .
Spiders and spiderwebs are also very common this time of year since the baby spiders have grown up and are more visible, and many spiders are out and about more, moving around to look for mates.
With so many kinds of eight-legged bugs running around (nearly 3,000 species in North America alone!), the most common house spiders are bound to pop up in your abode from time to time. And with ...
Jumping spiders have four pairs of eyes; three secondary pairs that are fixed and a principal pair that is movable. The posterior median eyes are vestigial in many species, but in some primitive subfamilies, they are comparable in size with the other secondary eyes and help to detect motion. [10]