Synonyms and other taxonomic changes
=Araneida
all North American spiders belong to suborder Opisthothelae
Numbers
~43,500 spp. in ~4,200 genera of ~110 families worldwide
(1)Identification
A guide to easily identifiable spiders:
(2); a good guide to common spiders and other arachnids:
(3)
Two body parts:
cephalothorax and
abdomen
Eight legs attached to cephalothorax
visible silk glands
Determining sex:
Look at the front of your specimen, where the "face" of the spider is. You will find two small appendages that resemble little legs. These appendages are called
pedipalps, and are used for sensing the spider's immediate environment, for assisting with eating, and for males, reproduction (specifically sperm deposition). Please refer to the Anatomy section above for a picture of a spider with the pedipalps labeled.
If the pedipalps resemble boxing gloves (the tips of the pedipalps are swollen), it is an adult male, e.g.
If the pedipalps are not swollen, it is either a female, or an immature. (Characteristics of the female genital opening, the
epigynum, may be used for species-level identification.).
Habitat info may help with ID. For example, Zygiella x-notata and Z. atrica occur in urbanized habitats, the former on buildings and the latter on trees. The similar-looking Parazygiella dispar is found in natural forest.
Images critical for identification
Eye arrangement will help you place a spider to family
Body pattern can help
Epigynum close-up for adult female
Palp close-ups for adult male, especially side views
Food
insects. Web-making spiders catch their prey with a web; hunting spiders ambush their prey
Life Cycle
Egg ⇒ Spiderling ⇒ Immature/juvenile/subadult ⇒ Penultimate ⇒ Adult
Spiders must shed their exoskeleton, or molt, in order to grow.
They will molt several times (4‒12) as needed to reach adulthood. A penultimate spider has signs of underdeveloped genitalia and will molt once to become adult. True spiders, or
araneomorphs, do not molt past adulthood;
mygalomorph spiders live much longer and keep molting once or twice a year through adult life.
Remarks
While it's true that most have venom (the single exception in our area: Cribellate Orb Weavers in the
Uloboridae) the bites of all but a few are only mildly painful, and have no lasting effects.
Spiders of Potential Medical Concern:
Spiders with persistent rumors of medically significant bites that are not supported by scientific literature:
Hobo Spider (Eratigena agrestis ≡Tegenaria agrestis) has never been proven as the culprit in spider bites on humans and has been shown NOT to be MEDICALLY SIGNIFICANT (
Gaver-Wainwright et al. 2011)
Relocating a spider
Carefully place a cup over the spider (careful not to pin the legs under the rim).
Gently slide the paper under the glass; as you push the paper, let the spider walk up onto the paper.
Once the paper is completely underneath the cup, pick up the paper and glass, making sure not to create gaps between the paper and glass
Take the spider to the new location.
Place the cup on its side on the ground and remove the paper.
Print References
Information on rearing and studying spiders in
(4)
Canadian fauna overview
(5)
Higher classification and global taxon numbers
(1)
