Another one for the chemists/zoologists

[DEmigh]

Several threads in the past couple of days have inspired this wild question. Specifically: the discussion about Ammolock II treated water still testing positive for ammonia; the discussion about new frogs resulting in fish mortality despite (apparently) negative ammonia tests; and the one (really) about the cat falling into the aquarium :)

Is the nitrogenous waste product excreted by frogs ammonia, urea, or some other related compound?

If frogs excrete some compound other than ammonia, will standard ammonia tests detect it?

Do cats wet themselves when they get wet? :D

Okay, sorry about that last one, but I'm serious about the first two.

Any takers :confused:

[mogurnda]

According to Schmist-Nielsen's Comparative Physiology, amphibians excrete urea. Teleost fish excrete ammonia. Interestingly, elasmobranchs (sharks, rays, etc) and coelacanths excrete urea.

In the tank, it's broken down to ammonia, though.

[DEmigh]

What a relief!

My flippant response on the diving cat thread had some possible basis in fact.

Follow on question:

The mechanism whereby urea is broken down into ammonia, is that bacterial, ionic (maybe a horrible misuse of terminology), enzymatic or what?

Thank you :)

[mogurnda]

You're welcome. I'm just glad that taking the course is finally paying off:D

Bacterial. Urea is quite stable in a sterile solution. Without getting into all the ugly details, our bodies put energy into combining CO2 with NH3 to make urea, so bacteria can get energy from breaking it back down.