Earthworms do not have hearts like humans; instead, they have a simpler circulatory system. They use aortic arches, which function as pumping vessels, to move blood.
Understanding Earthworm Circulation
Unlike mammals with a centralized heart, earthworms have a circulatory system that's distributed across their body. This system is vital for nutrient transport and waste removal.
- Aortic Arches: The reference mentions that earthworms have aortic arches. These aren't true hearts, but rather muscular vessels that contract to push blood. They function as the primary pumps within their circulatory system.
- Vessels: Earthworms possess blood vessels that carry blood throughout their bodies, ensuring every segment gets the necessary oxygen and nutrients.
How the Aortic Arches Function
Earthworms usually have five pairs of aortic arches encircling their esophagus. This arrangement means that while they don't have two hearts, they have multiple pump-like structures that work in coordination:
- Contraction: The aortic arches contract rhythmically, pushing the blood forward.
- Distribution: Blood then moves through the dorsal (upper) and ventral (lower) blood vessels.
- Capillary Network: Smaller capillaries distribute the blood to tissues and organs, delivering nutrients and oxygen.
- Return: The blood then travels back to the aortic arches, completing the circulatory loop.
The Misconception About Two Hearts
The idea that earthworms have two hearts is a common misconception. It's more accurate to say that they have multiple aortic arches that function as pumps. These arches help move blood in a closed circulatory system.
| Feature | Earthworm | Human |
|---|---|---|
| Pumping Organ | Aortic Arches | Heart |
| Circulatory Type | Closed | Closed |
| Number of Pumps | Multiple (5 pairs) | Single Heart |
Therefore, the statement “worms have 2 hearts” is a misunderstanding. They have multiple aortic arches which are pumping vessels.
