Which of the following respiratory organs are not supplied with blood vessels?

Options

A. The gills of a shark
B. The tracheae of a locust
C. The lungs of a rabbit
D. The skin of an earthworm

Answer

To solve the question of which respiratory organs are not supplied with blood vessels, we need to analyze each option provided:

1. **Gills of a shark**: Gills are specialized organs for gas exchange in aquatic animals. They are highly vascularized, meaning they have a rich supply of blood vessels to facilitate the exchange of oxygen and carbon dioxide with the surrounding water. Therefore, gills are supplied with blood vessels.

2. **Trachea of a locust**: The trachea is part of the insect respiratory system. It consists of a network of tubes that deliver oxygen directly to the tissues of the insect. The trachea does not have blood vessels; instead, gas exchange occurs directly between the air in the trachea and the body tissues through a process called diffusion. Thus, the trachea of a locust is not supplied with blood vessels.

3. **Lungs of a rabbit**: The lungs are respiratory organs in mammals, including rabbits. They are highly vascularized and have a rich supply of blood vessels to facilitate gas exchange between the air and the bloodstream. Therefore, the lungs are supplied with blood vessels.

4. **Skin of an earthworm**: Earthworms respire through their skin, which is moist and allows for gas exchange. The skin is also supplied with blood vessels, as the gases diffuse into the capillaries located just beneath the skin surface. Therefore, the skin of an earthworm is supplied with blood vessels.

After analyzing all options, we conclude that the correct answer is:

**The trachea of a locust is the respiratory organ that is not supplied with blood vessels.**