Do Spiders Pee? Animals, unlike plants, must all “urinate” despite undertaking the process in different ways. Urinating allow removal of unwanted salts, nitrogen, and also maintain water balance in their bodies. 
In humans, the urination process starts in the kidney while the bladder stores the urine (nitrogenous urea waste plus water) in liquid form before its ejected.
So, do spiders pee? The short answer is, NO, spiders don’t urinate like humans. But spiders poop-pee uric acid (from malpighian tubules akin to kidneys) that is semi-solid and won’t dissolve in water.
Simply, spiders won’t deposit urine and feces separately like humans. Spiders release the waste in a combined form (feces plus urine) through the anus.
Details: Do Spiders Pee? Urinate? 7 Spider FAQs
Spiders have malpighian tubules (comparable to mammalian kidneys) that’ll remove the nitrogenous waste in form of uric acid. The malpighian tubules will drain into the stercoral pocket (a pouch in its digestive tract).
However, unlike human urine, the uric acid is near-solid and won’t dissolve in water. Spiders pee-poop that’s semi-solid help them avoid losing water through their urine.
In the stercoral pocket, the uric acid is mixed with solid waste coming from the spiders digestive tract to form the semi-solid poop-pee that come out combined through the anus.
Conserves Water with Uric Acid
Insects and spiders will change their nitrogenous waste into uric acid – which is an insoluble and contains minimal water – as a water conservation method for the spider.
Comparatively, flying insects and birds produce dry ‘urine’that has uric acid since they avoiding a bladder with water helps them cut their weight.
Related: Do Spiders Have Brains?
Do Spiders Drink Water?
Simple answer is, YES, spiders drink water. While in the wild environment, the spiders will drink from droplets on the ground of vegetation. Further, they can drink from evening or morning dew that’s hanging on the spider’s web.
However, for the caged spiders, you should offer them fresh water using objects like small dish, damp sponge or bottle cap including for the tarantulas species. The Tarantulas will also drink the droplets of water gathered on foliage or leaves around them.
Despite that spiders do drink water must not make you think that the arachnids live in drains. For a spider that’s inside the house, the best water sources is water droplets from shower or tap , sink edges, or plugholes.
Definitely, spiders can’t drown but may remain trapped in the bath or sink due to being too steep or slippery. The whistling spider species creates a silk layer for their long burrow to ensure it remains humid and hydrated.
Raindrops dew can also provide a water sources for some spider species. Garden spider, wolf spider and wolf spider tend to get water from drinking the morning dew. They’ll take the water from dew via mound (silk-covered) at the door of their hideout.
Some spider species also drink nectar from the garden plants particularly when there are limited water sources such as rain, dew or tap water. Spider species like the whip spider use their pincers to suck water from sources like dew or nectar flowers.
Some Spiders Don’t Drink Water
The red back and black widow (while they’re not all venomous), interestingly, don’t drink water like humans or other spiders. These spiders get most of their required body fluids from sucking their prey.
These are comparable to mammals such as the koalathat don’t drink water but derive their fluids from eating eucalyptus (smooth-barked) among other plan leaves.
Related: Do Spiders Have Bones?
Size of Spider’s Pee-Poop
As noted above, spider’s poop and pee is mixed together – through their malpighian tubules to eliminate the nitrogenous waste. So, its fact that spiders don’t generate urine but will have the near-solid uric acid.
Spiders lack a clearly defined urinary tract comparable to that in mammals. Check this amazing answer on whether spiders pee or poop. You can use spider spray to control the arachnids that are unwanted indoors.
The spider’s pee-poop is small light brown, cream, or white colored that will appear like round drops. On size, these droppings measure around 1/16 – 1/8 an inch in diameter. Further, the spider’s poop mainly contains guanine – just like in the DNA.
