Despite the temperature being hot as blazes, mid-August is still considered the end of the swimming season in Japan. In our area of the Seto Inland Sea, it used to be said that after O-bon (around Aug. 15) the enko (sea nymphs) come out and can grab your legs and pull you down under the water to drown you. But these days the Japanese have abandoned that old-fashioned myth for the new-fashioned one — that the jellyfish come out after O-bon. So no one in their right mind would go swimming now.

But, having lived on a small island in the Seto Inland Sea for 15 years, I can tell you with confidence that the jellyfish have no idea when O-bon is. They do not have specialized jellyfish watches cinched around their slippery bodies that beep on Aug. 15 every year to inform them it is time to come out. The jellyfish are not waiting at the start gate like race horses, waiting to burst forward when the O-bon bell rings. . . . “And they’re off! The jellyfish have surged out of the gates and are racing toward the beach where they hope to sneak up on swimmers and sting them!”

Believe me, jellyfish are not Buddhist. They do not know their ancestors, and they could care less about O-bon. They have not passed a math test, let alone taken a physics class nor studied marine biology. The lunar calendar and tidal charts, however, they’re probably experts at.

And this is why the jellyfish come out when it’s convenient for them, not us. So if they do suddenly come out after O-bon, it’s most likely a coincidence — perhaps they all had the same vacation that week.

The truth is that there are jellyfish present all summer long. Some years there are many more than other years when there may be hardly any. But one thing is for sure — they’re always there. Sailing through the Seto Inland Sea, we sometimes come across sea carpets of translucent medusa of jellyfish packed so tightly you couldn’t even wedge a chopstick between them.

Some days the jellyfish venture closer to the shore than other days. As a result, swimmers who come to our beach do occasionally get stung, even at the beginning of the summer. Although the jellyfish here are not poisonous, and their sting will not put you in the hospital, I suppose there is always the infinitesimally small chance that you might have an allergic reaction and, well, die. In the off-chance that you were to die from a jellyfish sting in mid-summer, it certainly would be a shame. If the same were to happen after O-bon, however, people would say “I told you so!” and it would be seen as having been preventable. And wouldn’t it be embarrassing to have an epitaph that reads “Herein lies (your name) who died of a jellyfish sting because they swam after O-bon.”

While jellyfish may be sensitive to changes in water temperature, or changes in copepods, crustaceans and organic matter they feed on, they don’t seem to care whether these changes happen before or after O-bon.

When Japanese people tell me you can’t swim after O-bon “because the jellyfish come out,” I always wonder: Where do the jellyfish “come out” from? Is there some underwater jellyfish kingdom? Jellyfish are definitely not out in winter when the water is cold, so they must come from somewhere. And it’s not as if they winter in warm climes waiting for the trade winds to bring them back to Japan. No, these jellyfish have likely grown up here in the Inland Sea. Somewhere.

I have an idea on this. If you watch jellyfish swimming, and they do this so slowly that anyone can see, you will notice that they look like kanji characters would if they got damp and lost their shape. As a matter of fact, if you were to throw your kanji workbook into the sea right now, all of those characters would swim off the pages and go their own way. Especially the characters with the sanzui radical (the radical for water) would be very strong swimmers. So jellyfish are actually just swimming kanji.

So you can imagine schools of Japanese jellyfish spending their days doing rote morphing into kanji shapes with specialized sea jargon radicals. This technical kanji offers endless opportunities for fluid strokes accompanied by dabbing, dotting, or adding a swoosh or a chong-chong here and there.

It also explains what I believe is behind the kanji pulsing from flashing warning signs for sailors under bridges in the Inland Sea. Whereas you’d think that warning signs would be in simple Japanese, instead, when the going gets tough the Japanese get technical. As a sailor, I know that flashing kanji under the bridge near the Naruto Whirlpools is trying to tell me something really important — something that could make the difference between life and death — I just don’t know what it is! Or perhaps it is just a gentle reminder that “Scylla the six-headed monster and Charybdis the whirlpool are on either side of the rushing water underneath the bridge. Good luck!”

The sign under the Seto Ohashi Bridge eludes me as well. I think that what happens is that just as our boat is about to approach the bridge, some truant jellyfish jump out of the water and plaster themselves on the sign and point their tentacles in never-before-seen directions.

Once the jellyfish graduate from tentacle kanji school, they are set free in the Seto Inland Sea, where they go look for jobs — stinging swimmers at the beach. And yes, you guessed it — graduation happens to be on Aug. 15 every year.

You may think this is a whimsical explanation of where jellyfish come from, but it’s only as whimsical as thinking you can’t swim after O-bon.

Follow Amy Chavez on Twitter @JapanLite.

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