Respiration in Animals

Different animals have different modes of respiration:

• Unicellular animals: Diffusion
• Animals that live inside soil (like Earthworms): Breathe through the skin
• Aquatic animals: Gills which extract dissolved oxygen in water
• Insects (like grasshopper, cockroach, housefly, mosquitos): tiny holes called spiracles connected to tubes called tracheae.
• Lands animals (like humans, birds, lizards) have lungs.

Respiration in Amoeba:

Amoeba lives in water.

• Water has oxygen dissolved in it.
• This oxygen diffuses into the body of the amoeba through its cell membrane .
• The oxygen is used for respiration inside the cell and energy and carbon dioxide are released .
• Other animals like paramecium and planaria also respire through their cell membranes.

Respiration in Earthworms:

• Earthworms exchange gases through their skin.
• The skin is moist, thin and has a good blood supply.
• The oxygen is absorbed through its moist skin and transported to the rest of the body for use in respiration.
• Carbon dioxide produced as waste is expelled through its skin .
• Leeches also respire like earthworms through its skin.

Respiration in Fish:

Fishes have special organs for breathing called gills .

• Fishes live in water, and water has dissolved oxygen in it.
• When the water passes through the gills, the gills extract dissolved oxygen from the water.
• The water goes out through the gill slits.
• The oxygen is carried with the blood to different parts of its body.
• Carbon dioxide is brought back by the blood to the gills, which expel it into the surroundings.
• Gills cannot take in oxygen from the air . So aquatic animals like fishes die when taken out of water.
• Eg: Prawns, mussels