Question

How many hearts does an earthworm possess?
A. \[6\] pairs
B. $5$ pairs
C. $2$ pairs
D. $1$

Answer 1

Hint: The "hearts" of an earthworm reside in pairs located at the mouth of the insect, and act just like a human heart, while earthworms breathe oxygen via their skin and need moisture for breathing. These heart-like organs, thus the term aortic arch, carry a similarity to arches.

Complete answer:
First, we should know about earthworms to answer this question. In many habitats, earthworms play an essential part, breaking down decaying organic matter into basic components for plant use. Earthworms help improve soil consistency by breaking down large bits of organic matter to humus. Some animals, like birds, need them for food, and although fishing, humans sometimes use them as bait. Some people still store worms in specialised tanks where organic waste is dumped into them.
Now, let us find the solution from the options-
-Earthworm bodies have an additional layer of muscle, skin (epidermis) and cuticles.
-They have a tube-like form and about $100$ and $150$ segments, which helps the species to travel quickly across the soil. Inside this cavity, the innards, therefore, often organize themselves.
- As it is an invertebrate, Earthworm may not have a real heart but relates to them as heart as they have possessed pairs of aortic arches.
-The hearts in the ${\text{7th & 9th}}$ segments become lateral hearts with 4 valve pairs, while those in the $12th$ & $13th$ segments are named lateral oesophageal hearts with 3 valve pairs.

Thus, the correct option is an option (B) $5$ pairs.

Note:
An earthworm primarily has blood passing across veins. Within the earthworm, three major arteries provide blood to muscles. Few types of annelids use their muscles to monitor the heartbeat, while earthworms utilize nerve cells, similar to vertebrates. In this way, the heart of an earthworm may look more like a proper human heart than most other members of the grouping of annelids.