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How do Angelfish How do Angelfish Breathe?Breathe?

A Presentation for The A Presentation for The Angelfish Society Angelfish Society

June 8, 2008June 8, 2008

By Tamar StephensBy Tamar Stephens

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How Do Angelfish How Do Angelfish Breathe?Breathe?

““That’s easy,” you might say. “They That’s easy,” you might say. “They breathe through their gills.”breathe through their gills.”

Of course, you are right, but do you know Of course, you are right, but do you know how gills actually work? how gills actually work?

Why can angelfish breathe underwater, but Why can angelfish breathe underwater, but human beings can’t?human beings can’t?

Can angelfish breathe air when they are Can angelfish breathe air when they are out of the water? Why or why not?out of the water? Why or why not?

Do angelfish inhale and exhale?Do angelfish inhale and exhale? How much oxygen do angelfish need in How much oxygen do angelfish need in

their water?their water?

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Why do we need to breathe Why do we need to breathe in the first place?in the first place?

Because we need oxygen, right?Because we need oxygen, right? But why do we need oxygen?But why do we need oxygen? We need oxygen for a chemical reaction to We need oxygen for a chemical reaction to

“burn” glucose to release energy. This is “burn” glucose to release energy. This is how our cells obtain energy to function. how our cells obtain energy to function.

Carbon dioxide is a waste by-product, Carbon dioxide is a waste by-product, which we release when we exhale.which we release when we exhale.

GLUCOSE + OXYGEN GLUCOSE + OXYGEN CARBON DIOXIDE + WATER + ENERGY CARBON DIOXIDE + WATER + ENERGY

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How does oxygen get to our How does oxygen get to our cells?cells?

Well, you probably all know the answer to this Well, you probably all know the answer to this one. one.

We use our diaphragm and chest muscles to We use our diaphragm and chest muscles to inhale to draw oxygen into our lungs and to inhale to draw oxygen into our lungs and to exhale to get rid of carbon dioxide. exhale to get rid of carbon dioxide.

The right side of our heart pumps blood to our The right side of our heart pumps blood to our lungs to pick up oxygen and get rid of carbon lungs to pick up oxygen and get rid of carbon dioxide. dioxide.

Our lungs have numerous tiny balloon-like sacs Our lungs have numerous tiny balloon-like sacs that are full of capillaries. The capillaries absorb that are full of capillaries. The capillaries absorb oxygen into the blood stream and give release oxygen into the blood stream and give release carbon dioxide.carbon dioxide.

Then the oxygen-rich blood returns to the left side Then the oxygen-rich blood returns to the left side of the heart to be pumped through our arteries to of the heart to be pumped through our arteries to deliver oxygen to the cells in all parts of our body. deliver oxygen to the cells in all parts of our body.

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It works the same way in It works the same way in fish, sort of…fish, sort of…

In fish, it sort of works the same way. The In fish, it sort of works the same way. The heart pumps blood to the gills to pick up heart pumps blood to the gills to pick up oxygen and release carbon dioxide.oxygen and release carbon dioxide.

But a fish heart is different from a human But a fish heart is different from a human heart. Fish hearts only have two heart. Fish hearts only have two chambers! chambers!

After the heart pumps blood to the gills to After the heart pumps blood to the gills to pick up oxygen and release carbon pick up oxygen and release carbon dioxide, the blood flows to the rest of the dioxide, the blood flows to the rest of the body organs and tissues before returning body organs and tissues before returning to the heart. to the heart.

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Do Fish Inhale and Do Fish Inhale and Exhale?Exhale?

No, they do not inhale and exhale!No, they do not inhale and exhale! Fish accomplish “breathing” in one of two Fish accomplish “breathing” in one of two

ways.ways. Some fish, such as sharks, need to swim Some fish, such as sharks, need to swim

through the water constantly to maintain through the water constantly to maintain a flow of water across the gills.a flow of water across the gills.

Other fish, including angelfish, swallow Other fish, including angelfish, swallow water through their mouths into the gill water through their mouths into the gill chamber and expel it out through the chamber and expel it out through the gills.gills.

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Gills have two main Gills have two main parts.parts.

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The OperculumThe Operculum The operculum, The operculum,

or gill cover, or gill cover, protects the protects the fragile tissue of fragile tissue of the gills. the gills.

The operculum The operculum also helps also helps direct water to direct water to to flow through to flow through the array of gill the array of gill filaments.filaments.

Photo of leopard angelfish from Gil Repetto

Operculum covers the gills.

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Gill filaments and Gill filaments and lamillae lamillae

The gills consist of sheet-like filaments.The gills consist of sheet-like filaments. The filaments are transected by many small The filaments are transected by many small

projections called lamillae, which contain tiny projections called lamillae, which contain tiny blood vessels. blood vessels.

Lamillae are where gases are exchanged Lamillae are where gases are exchanged between the water and the blood stream.between the water and the blood stream.

Gill lamillae provide lots of surface area for exchange of carbon dioxide and ogygen.

Picture from http://www.marinebiology.org/fish.htm#How%20Fish%20Breath

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How do lungs compare with How do lungs compare with gills?gills?

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Air versus water – lungs Air versus water – lungs versus gillsversus gills

Air contains about Air contains about 20% ogygen, or 20% ogygen, or 20,000 parts per 20,000 parts per million (ppm).million (ppm).

Lungs extract about Lungs extract about 25% of that oxygen 25% of that oxygen when we breathe.when we breathe.

Cold water only holds Cold water only holds about about 8 to 9 ppm8 to 9 ppm dissolved oxygen. dissolved oxygen. Warm water as found Warm water as found in our angelfish tanks, in our angelfish tanks, holds less oxygen - holds less oxygen - about about 4 to 5 ppm!4 to 5 ppm!

Gills extract about 80% Gills extract about 80% of the dissolved oxygen of the dissolved oxygen from the water. from the water.

Gills have a much harder job than lungs! They are also much more efficient!

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So, can angelfish breath out So, can angelfish breath out of water?of water?

Alas, no, they cannot. Alas, no, they cannot. The reason is because all of the The reason is because all of the

lamillae will collapse when the fish is lamillae will collapse when the fish is removed from the water. So even if removed from the water. So even if you keep the gill area moist, the fish you keep the gill area moist, the fish will start to suffocate.will start to suffocate.

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Why can’t people breathe Why can’t people breathe under water?under water?

Our lungs simply do not have Our lungs simply do not have enough surface area to extract enough surface area to extract enough oxygen from the water to enough oxygen from the water to keep us alive. So we will suffocate keep us alive. So we will suffocate if we try to breathe water. if we try to breathe water.

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I hope you enjoyed this I hope you enjoyed this presentation.presentation.

Hopefully you have a little more Hopefully you have a little more understanding of how gills work, and understanding of how gills work, and a new appreciation for the efficiency a new appreciation for the efficiency of this remarkable organ!of this remarkable organ!

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The EndThe End

Now back to the chat room for Now back to the chat room for discussion!discussion!