- How do they breathe?- How do they breathe?

• Just like animals, plants need to breathe too…

• Do plants have lungs?• Do plants have gills?• Then how do they breathe?

How do Plants breathe?• Gases such as oxygen and carbon

dioxide enter or leave a plant through tiny holes called stomata (singular – stoma).

• They are mostly found on the underside of its leaves and on its stems.

Stomata

• There are about 20-1000 stomata per mm2 of the leaf, depending on the type of plants.

• The highest number of stomata is found on the leaves of the Spanish oak tree. There are around 1200 stomata per mm2.

• During the day, the stomata are usually open so that carbon dioxide which is needed to make food, can enter the plant.

• At the same time, excess oxygen produced by the plant also leaves the plant through its stomata.

• At night, when the plant is not making food, oxygen enters and carbon dioxide leaves the plant through its stomata.

• Remember…oxygen is needed at all

times for respiration, even when the plant is making food!

Cross-sectional view of the leaf

Open stoma Closed stoma

• The roots of a plant also need oxygen which they obtain from the air spaces in the soil.

• Do you know…If you give too much water to

a plant in a pot you could kill the roots by drowning them!

Mangrove PlantsIn order to breathe in mud, mangrove trees snorkel for air. They develop air-breathing roots which take in air aboveground.

These roots have special tiny pores on their surface to take in air. Only air can enter these pores, not water or salts.

The roots also contain large air spaces that can store air. During high tide, when the roots are below water, there is still a ready supply of oxygen.

- How do fish breathe?- How do fish breathe?

Animals living in underwater have Animals living in underwater have no problem in removing carbon no problem in removing carbon dioxide because it dissolves very dioxide because it dissolves very easily in water. Their problem is easily in water. Their problem is how to obtain enough oxygenhow to obtain enough oxygen..

The amount of oxygen dissolved in the water The amount of oxygen dissolved in the water depends upon the depends upon the water temperature but, but, in general, if the water is at 15°C there is 30 in general, if the water is at 15°C there is 30 times more oxygen in the air than in water.times more oxygen in the air than in water.

Fish breathe by Fish breathe by using using GILLSGILLS..

Gills are found on Gills are found on either side of its either side of its heads.heads.

GillsGills The gill is made up of The gill is made up of

tiny flapstiny flaps that are rich that are rich in blood.in blood.

These flaps increase These flaps increase the surface area of the the surface area of the gills.gills.

The large surface area The large surface area and the many and the many blood blood vesselsvessels enable the fish enable the fish to absorb more oxygen to absorb more oxygen from the water.from the water.- A Fresh Gill

- A Spoiled Gill

oxygenoxygen present in present in the water is the water is absorbedabsorbed into the into the blood vessels blood vessels through the gills.through the gills.

carbon dioxidecarbon dioxide is is removedremoved from the from the blood vessels blood vessels through the gills.through the gills.

As water passes over the gills of a fish,As water passes over the gills of a fish,

The water that The water that entersenters the mouth of a fish the mouth of a fish has has more oxygenmore oxygen than the water leaving than the water leaving the fish.the fish.

The water that The water that flows outflows out of the gills of a of the gills of a fish has fish has more carbon dioxidemore carbon dioxide than the than the water entering the fish.water entering the fish.

How Do Mudskippers How Do Mudskippers Breathe?Breathe?

In waterIn water, mudskipper , mudskipper breathe through breathe through gillsgills like other fishes.like other fishes.

Out of waterOut of water, , mudskippers can hold mudskippers can hold water in enlarged water in enlarged gill gill chamberschambers which lock which lock shut on land. shut on land.

When the oxygen in the water runs out, When the oxygen in the water runs out, they have to replenish the used water in they have to replenish the used water in their gill chambers with fresh water, so their gill chambers with fresh water, so they cannot stay far from water.they cannot stay far from water.

Mudskippers also Mudskippers also absorb airabsorb air through their through their skinskin which is rich with blood vessels, so which is rich with blood vessels, so long as the skin remains long as the skin remains moistmoist..