Respiratory Organs in Animals: Types of Breathing Mechanisms

Just like human beings, animals also depend on the respiration process for living. However, the respiration process and the respiratory organs may differ from one animal to another. Not every animal has lungs in the chest cavity for completing the respiration process. Sometimes, respiration in animals depends on the habitat of the organism. For example, the respiration process for aquatic animals can differ from those who live on land. Respiration is a continual and voluntary process that usually involves intaking oxygen and liberating carbon dioxide. Read on to know more about respiration in animals and how it is different from human beings. 

Respiratory organs in lower organisms 

Lower organisms like amoeba and paramecium respire via their cell membranes. The respiratory gases diffuse through the cell membrane of lower organisms. Lower organisms do not have any specific respiratory organ and depend on the diffusion of gases. Another example of respiration in lower organisms is the hydra which respires through its moist body surface. 

Respiratory organs in cockroaches 

There are different types of breathing in animals on earth. Cockroaches have a unique respiratory system as compared to other animals. A cockroach has spiracles on the side of its body that support the respiration process. Spiracles are small exterior openings that help the oxygen-rich air to get into the internal respiratory system. The internal respiratory organ of a cockroach is made of tracheae that are a network of air tubes. From the tracheal tubes, the oxygen-rich air then passes to several tissues and cells inside the body of a cockroach. The spiracles also help cockroaches in breathing out carbon dioxide-rich air. 

Respiratory organs in earthworm 

If you ever touch an earthworm with your hands, it will feel slippery. It is because the skin is the main respiratory organ of an earthworm. Via the moist skin and capillaries of an earthworm, oxygen-rich air passes into its body. The haemoglobin dissolved in the blood of an earthworm picks the oxygen passing through the skin. Via active transport, earthworms can pass water and salts from their skins. Once the oxygen is captured by the haemoglobin, carbon dioxide is released via the skin of the earthworms. 

Respiratory organs in frogs 

There are different types of respiration in animals but, the frog is an exceptional organism. A frog possesses three mechanisms of respiration. An adult frog is capable of cutaneous, buccal and pulmonary respiration. 

In cutaneous respiration, a frog breathes-in air via the moist outer skin. When frogs are underwater, cutaneous respiration is the only option. However, cutaneous respiration can take place outside the water also. The outer moist skin of frogs is highly permeable to gases. The oxygen-rich air first dissolves in the moist skin and then mixes with the blood. To keep their skin moist, frogs stay near water as the oxygen has to first dissolve on a moist surface. Due to the same reason, frogs secrete mucus for keeping their skin moist. 

Respiration in animals mostly occurs via nostrils. In buccal respiration, a frog breathes-in air via its nostrils. The buccal cavity of frogs continuously expands and shrinks when frogs respire via nostrils. During buccal respiration, the glottis in a frog remains closed to prevent the flow of air from the lungs to the buccal cavity. The buccal cavity of a frog consists of mucus epithelial lining, which is responsible for absorbing oxygen. The mucus lining in the buccal cavity also helps a frog in discharging carbon dioxide. 

When on land, a frog usually undergoes pulmonary respiration. In pulmonary respiration, a frog breathes in and out via its lungs. However, the lungs of a frog are poorly developed which is why pulmonary respiration is often supported by the buccal cavity and the moist skin of a frog. With lungs alone, a frog gets an insufficient oxygen supply. 

Respiratory organs in fishes 

Do you know that aquatic animals breathe faster than terrestrial animals? It happens due to the less amount of oxygen present in water as compared to land. Since the supply of oxygen is less in water, aquatic organisms respire faster to intake more oxygen. 

Respiration in animals that live in water usually happens via gills. Gills are placed outside the skin of a fish and consist of blood vessels. To protect the gills, fishes have gill slits. Through their mouth, fish take water into their bodies. When the water goes into a fish’s body, oxygen is absorbed and transferred into the blood vessels. The blood vessels then transport the oxygen to different cells in a fish’s body. Once the oxygen is consumed, fishes release carbon dioxide via the gills. 

Larger aquatic animals like whales and dolphins are also mammals. They usually have a blowhole at the top of their skull that helps them in respiration. Dolphins and whales usually come up to the surface of the water to respire via their blowholes.