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