Do fish wee?

[b13thy]

Do they? Do spiders?

[maggie01]

fish certainly do thats why you get amonia in fish tanks. I have three fish tanks, never studied spiders

[Clanad]

In one form or another, all living things, including plants "wee".  Taking in nutrients and giving off waste... so, yes spiders (arachnids), along with their cousins, the insects do the same...

[b13thy]

It seems that nowhere is safe from the 8 legged beasties - just when i thought i was safe from the spiders now i find out they can urinate on me whilst i'm in bed - fantastic

[Kilala]

Sounding a tad paranoid, b13thy... Start to worry when you strap phone books to your feet, fashion a hat out of foil and start rocking, muttering "The Spiders, they can't get me now..." 

[Fern57]

Fish excrete about 20% of their body weight worth of dilute urine every day. This is handled by the kidneys of a fish. This is quite a bit more than most people realize! This urine contains all the biological wastes of the fish that are dissolvable in water. The rest are excreted as solid waste. As you can imagine, all of the waste in urine builds up quickly in a tank. This is why frequent water changes are a must, even in tanks which appear clean.
http://fishiezoo.com/articles/osmoticpressure.html

Spiders do not have separate urine and feces, and their droppings consist largely of guanine, which is a component of DNA and found in all living things.
http://www.washington.edu/burkemuseum/spidermyth/myths/m isc.html