Leech has 32 brains.
A leech’s internal structure is segregated into 32 separate segments, and each of these segments has its own brain.
Leech is an annelid. They have segments. However, unlike typical annelids, leech’s external and internal segmentation do not correspond to each other. If the internal body is examined, it can be seen that the body is divided into 32 parts or segments which have their own corresponding brain. These are not individual brains, but the same brain which is segmented into 32, as per leech’s segments. Each of this segment possesses its own neuronal ganglia that are linked with the next. Hence, in other words, it is the same single brain that exists in 32 segments throughout the body, anatomically speaking. Physiologically, as every ganglion regulate its corresponding segment and operate independently, it is said to physiologically possess 32 brains.
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