Organisms devoid of respiratory, excretory, and circulatory organs
Organisms known as sponges are examples of creatures that lack traditional respiratory, excretory, and circulatory systems. Below, we will explain in detail why sponges do not possess these organs.

Respiratory System
- Sponges do not have a specialized respiratory system like lungs or gills.
- They rely on simple diffusion to obtain oxygen from water.
- Oxygen enters their bodies through specialized cells called choanocytes, which line their internal cavities.

Excretory System
- Sponges lack a centralized excretory system such as kidneys.
- Waste products are expelled from their bodies through simple diffusion.
- Ammonia, the primary waste product, diffuses out of their cells into the surrounding water.

Circulatory System
- Unlike most animals, sponges do not have a circulatory system with a heart and blood vessels.
- Instead, nutrients and oxygen are transported throughout their bodies via diffusion.
- Waste products are also removed in a similar manner.
In conclusion, sponges have evolved unique mechanisms to survive without traditional respiratory, excretory, and circulatory organs. Their simple body structure and reliance on diffusion highlight the diverse ways in which organisms have adapted to their environments.