Q. Dear Twig: How do seahorses go to the bathroom?
A. Seahorses are fish. You probably know that. So they go to the bathroom like other fish do. Food goes into the mouth, to and through the intestine, then the food that isn't digested and absorbed there goes out the anus ("AY-nuss") as feces ("FEE-seez") — usually, in this case, small pellets.
Seahorses actually have an inefficient digestive system, says the "Biology of Seahorses" Web page of a group called Project Seahorse. "Food passes through rapidly and is often excreted in a partially digested state," says the book Seahorses by Frank Indiviglio.
Seahorses get rid of urine as well. It's made up of water and of filtered-out waste from the blood. It goes from the kidneys, into the urinary bladder, then out the urogenital ("yer-oh-jen-ih-tull") pore. That part's next to the anus; together they make up the vent. The vent is on the front of a seahorse (the bottom of a regular fish), above the tail and, if a male, the brood pouch.
P.S. Another way? They raise their fin, ask the teacher, then swim down the hall and turn right.
Ba ha ha ha ha ha heeeee! Get it? Raise their fin? That's so finny I forgot to laugh.
Thanks to Elise of Lakeville Elementary School, Lakeville, Ohio, for this week's question.
"Seahorses have an extremely reduced stomach, a characteristic found in many fishes that, like them, feed continuously on small prey." So says the "Seahorse Anatomy" Web page of the Scripps Institution of Oceanography, La Jolla, Calif., http://aquarium.ucsd.edu/Education/Learning_Resources/Secrets_of_the_Seahorse/swf/body.swf. Check it out: It lets you roll your cursor over a seahorse to see the parts inside.
Project Seahorse: http://seahorse.fisheries.ubc.ca/.
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