September 23, 2007

Sunfish at Monterey Bay Aquarium

The Wikipedia entry on ocean sunfish says baldly, "The ocean sunfish resembles a fish head without a tail." I hope this unobjectionable observation stirs no controversy over in the wiki's disussion page, being about as nuetral a way of describing the beast's form as might commonly occur to the most excruciatingly disinterested observer.

Viewed from the side the ocean sunfish does look like a fish head without a tail, the creature terminating in an odd florescence of rows of bulbous growths instead of the culminating tail of the fish as commonly concieved. I would only add that the ocean sunfish is a very large and widespread and relatively recent addition to the world's oceans that resembles a fish head without a tail. Its kind arose in the late Eocene, about 50 million years ago. Ocean sunfish now occupy tropical and temperate waters in every ocean. Ocean sunfish grow to enormous size. Two of them are on view at the Monterey Bay Aquarium.

Ocean Sunfish at Monterey Bay Aquarium

From the front of the creature to its matched dorsal and anal fins, the sunfish follows the general plan of body parts of a fish. The head of the sunfish does look like a head in profile, and it has all the forward parts of the head, the mouth and nose and eyes and gills, right up front where they're expected of a fish.

My wife immediately recognized J. Edgar Hoover's profile here:

J. Edgar Fish

The eyes of the ocean sunfish are perched in little pods of flesh outside the beast's skull, which give them uparalleled range of motion at the risk of being snipped right off by some passing other creature, of which the seas are known to abound.

The whole eye-on-a-stalk design in general would seem to suffer from this everpresent probability of passing blindness as a tradeoff for the best possible view of its surrounds, which is presumably why the eye design that hugs closer to the skull, willingly trading the valued acuity of eye-on-a-stalk for the more highly valued persistence of vision afforded its recessed postion is the fashion even among the common run of fish. Continuity of sight slightly trumps acuity of sight here in the race to put the eye somewhere or other on the fish. But, still, there it is the eye of the ocean sunfish, out there in its little cup of flesh, the cup capable of waggling the eye around to get the full view if needs be.

The whole of the fish 

Just past the jutting fins atop and below the creature, just behind what up until then follows in the main the sequence of segments given for a fish's shape, with the head accounted for and then the midpart coming along just there behind it with its fins and all being well disposed of, and, but then …, some profoundly different segment pops up to terminate the thing: the unique truncated remainder of the ocean sunfish instead of the valued tail as given almost everywhere else for the regular ending of a fish.

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