Search results
Results from the WOW.Com Content Network
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.
Spiders (order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, [2] and spinnerets that extrude silk. [3] They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms.
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 ...
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 .
Copulatory opening: An opening in the ventral abdomen of female spiders; in entelegyne spiders, a double opening in the epigyne through which the embolus is inserted; in haplogyne spiders, a single opening through which male palpal bulb is inserted [6] Coxa: see segments; Crenulate: Having longitudinal ridges [7]
In bees, the maxillae and labium have been modified and fused to form a nectar-sucking proboscis. In the order Hemiptera, the true bugs, plant hoppers, etc., the mouthparts have been modified to form a beak for piercing. The labium forms a sheath around a set of stylets that consist of an outer pair of mandibles and an inner pair of maxillae.
The spiders are most often observed in railway tunnels and mines since these are more likely to be visited by humans. The young spiders are, after several instars (and in contrast to the adults), strongly attracted to light [ 2 ] —probably an evolutionary adaptation which ensures the spread of the species to new areas (see Life cycle for ...