MadSci Network: Zoology
Query:

Re: how can you tell if a fish is breathing?

Date: Wed May 7 09:51:53 2003
Posted By: Sue Kelly, Faculty, Environmental Science & Biology, Piedmont College
Area of science: Zoology
ID: 1047672841.Zo
Message:

Fish get their oxygen directly from the water in which they live.  So, 
they don't really breathe like people do by getting oxygen from air.  The 
term "respire" is probably more accurate.

Fish use their gills to obtain oxygen from the water.  The gill is a very 
special tissue that has many, many blood vessels running through it.  As 
water passess over the gills of a fish, oxygen from the water diffuses 
across the gill cell membrane and then into the blood.  The blood can then 
carry the oxygen to the other tissues in the fish (like the muscle, the 
eye, the stomach, etc.).

In a typical tank fish (those we keep as pets), you can usually tell if 
the fish is respiring by watching the opercula - the flaps on the side of 
the fish just behind the head.  Inside the opercula are the gills.  The 
way many fish keep water flowing over the gills when they are not moving 
is to use muscles to create a vacuum of sorts - one that will pull water 
in through the mouth and then expel it across the gills & out the 
opercula.  So, if the opercula are moving, the fish is respiring.  

Fish can also use what is known as "ram ventilation" whereby they swim 
with the mouth open.  This enables water to enter the mouth and exit 
through the opercula.  This technique keeps fresh, oxygenated water 
flowing over the gills.

Interestingly, there are some fish that have lungs or other structures 
that enable them to get their oxygen from air.  A great example of this is 
the Beta - a very common pet fish right now.  The Beta (or Siamese 
fighting fish) uses what is known as a labyrinth organ and needs to have 
access to air in order to survive.

More detailed information on fish respiration can be found by visiting these sites:

http://www.lookd.com/fish/respiration.html

http://www.csuchico.edu/~pmaslin/ichthy/fshrsp.html

http://users.northnet.com.au/~cycen/bettainfo.html

http://www.exotictropicals.com/encyclo/fresh/anabantoids/labyrinth.htm


Thanks for your question!

Sue








Current Queue | Current Queue for Zoology | Zoology archives

Try the links in the MadSci Library for more information on Zoology.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@www.madsci.org
© 1995-2003. All rights reserved.