Friday, September 9, 2011

This Horse is Not an Equus

In these maddened times when elephants fight donkeys, a little excursion into the wonders of nature might be appropriate. A gift we purchased led to a discussion about the seahorse—which is actually a fish. Humanity’s long, long association with the horse—domestication is said to have begun before 3500 BC—no doubt led to the instant identification of the seahorse, when first encountered, with its huge land-based look-alike—up to a point, that is. The official name of this creature is Hippocampus. That word, from the Greek, comes from hippos, horse, and kampos, sea monster, a word that etymologists, using their favorite word, perhaps, say might be linked to kampe, caterpillar, a creature that loomed larger than life for us this summer. Hippocampus is the genus; there are some 50 species beneath that. The higher-up Family name is Syngnathidae, collectively the pipefish—which gives some indication of how these creatures move: pipefish are elongated worm- or snake-like swimmers.

To the left is a photograph of a Hippocampus hystrix, called the spiny seahorse (source). I assume, therefore that hystrix means spiny. As you see, the artist who fashioned the gift we purchased was imitating nature fairly closely. If you would like to see seahorses galloping around in the water, this absolutely delightful YouTube film will show them to you in action (link).

Being a Renaissance woman (her field was physiological psychology in school), no sooner had I produced the name of the seahorse genus Brigitte reminded me that each of us carries a little seahorse embedded deeply in our brain. That’s the hippocampus, of course. It is located in the medial temporal lobe of the brain (therefore in its middle). The temporal lobe is behind and lower than the massive frontal lobe.

The function of this structure is the consolidation of short-term and long term memory. Damage to the hippocampus occurs early in Alzheimer’s disease. The hippocampus is also active in spatial navigation. Navigation? Why of course. That is a sea-faring skill. Why this part is called the hippocampus becomes evident when we place the two hippocampi side by side—as Wikipedia helpfully does in a picture on the subject (link).

All horses aren’t equine, not all elephants are wise, and not every donkey is stupid. But one certainly hopes that each donkey shall remain at least as stubborn as donkeys are supposed to be.

2 comments:

  1. Oh, those images of sea horses are lovely, and the gift for Adam and his new wife is lovely. What an unlikely creature. And what an interesting point about the hippocampus.

    To wise and stubborn donkeys!

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  2. Really nice things to know here...

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