What are the differences between respiratory system of aquatic animals and non- aquatic?

Aquatic animals, such as fish and aquatic insects, exchange gases with the water they live in, while non-aquatic animals, such as mammals, birds, and reptiles, breathe air. Here are the key differences between their respiratory systems:

Aquatic Animals:

1. Gills: Aquatic animals possess specialized structures called gills, which are highly vascularized and densely packed with capillaries (small blood vessels).

- Gills are usually present in pairs on both sides of the animal's body.

- Water passes over the gills, and oxygen from the water is absorbed into the blood through the capillary walls.

- The blood then transports oxygen to the animal's cells.

2. Countercurrent Exchange System: Aquatic animals have a countercurrent exchange system in their gills.

- Blood flow in the capillaries and water flow over the gills are in opposite directions, which maximizes oxygen absorption.

3. Respiratory Pigments: Aquatic animals usually have respiratory pigments, such as hemoglobin, which bind with oxygen and enhance its transport in the bloodstream.

4. Diffusion of Gases: Oxygen and carbon dioxide are exchanged through diffusion across the gill surfaces due to concentration gradients between the water and the blood.

5. Less Developed Lungs: Some aquatic animals, such as fish, lack well-developed lungs or lung-like structures.

Non-Aquatic Animals:

1. Lungs: Non-aquatic animals possess lungs, highly branched internal structures that facilitate gas exchange.

- Lungs are adapted to absorb oxygen and release carbon dioxide from the air.

2. Trachea and Bronchi: Air enters the lungs through a trachea (in insects) or trachea (in mammals and other vertebrates). The trachea then branches into smaller bronchi that carry air to different regions of the lungs.

3. Alveoli: The smallest structures responsible for gas exchange in lungs are called alveoli.

- Alveoli are tiny, balloon-like structures with a large surface area for efficient gas exchange.

4. Pulmonary System: Non-aquatic animals have a well-developed pulmonary system, including air passages, lungs, and associated structures that enable air ventilation.

5. Inhaling and Exhaling: Non-aquatic animals actively inhale air into the lungs and exhale it back out, facilitating the exchange of oxygen and carbon dioxide.

6. Ventilation: Respiratory muscles are responsible for lung ventilation, which involves expanding and recoiling the lungs to bring in and expel air.

These differences in respiratory systems reflect the adaptation of aquatic and non-aquatic animals to their respective living environments and the efficient acquisition and utilization of oxygen.