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Spiders that spin webs typically have three claws, the middle one being small; hunting spiders typically have only two claws. Since they do not have antennae, spiders use specialised and sensitive setae on their legs to pick up scent, sounds, vibrations and air currents. [6] Some spiders, such as the Australian crab spider, do not have claws.
Carnivores have chelicerae that tear and crush prey, whereas herbivores can have chelicerae that are modified for piercing and sucking (as do parasitic species). In sea spiders, the chelicerae (also known as chelifores) are short and chelate and are positioned on either side of the base of the proboscis or sometimes vestigial or absent.
Almost all spiders have venom glands and can inject the venom through openings near the tips of their fangs when biting prey. The glands that produce this venom are located in the two segments of the chelicerae, and, in most spiders, extend beyond the chelicerae and into the cephalothorax. [ 2 ]
However, spiders' chelicerae form fangs that most species use to inject venom into prey. The group has the open circulatory system typical of arthropods, in which a tube-like heart pumps blood through the hemocoel, which is the major body cavity. Marine chelicerates have gills, while the air-breathing forms generally have both book lungs and ...
Seta (plural setae): A bristle; [22] spiders have a variety of hair-like structures of increasing size that are referred to as hairs, bristles (setae) or spines [29] Sigillum (plural sigilla): A circular indentation on the outside of the spider, showing where an internal muscle is attached; [ 30 ] particularly on the sternum in some ...
Wolf spider. What they look like: With over 200 species of wolf spiders crawling around, it’s no wonder that they range in size and appearance.“The largest species can be up to an inch and a ...
Now, however, it appears that non-orb spiders are a subgroup that evolved from orb-web spiders, and non-orb spiders have over 40% more species and are four times as abundant as orb-web spiders. Their greater success may be because sphecid wasps , which are often the dominant predators of spiders, much prefer to attack spiders that have flat webs.
In spiders, the coxae frequently have extensions called maxillae or gnathobases, which function as mouth parts with or without some contribution from the coxae of the anterior legs. The limbs themselves may be simple tactile organs outwardly resembling the legs, as in spiders , or chelate weapons (pincers) of great size, as in scorpions .