According to Justin McCurry, Tokyo correspondent for The Guardian,
The Guardian: In Japan, it’s raining tadpoles …
Meteorologists admit they are bewildered by a spate of incidents in which the creatures appear to have fallen from the sky. People around the country have reported witnessing the phenomenon since the first sightings of stranded tadpoles were made in Ishikawa prefecture last week.
The article continues:
One popular theory is that the creatures were sucked up by waterspouts but meteorologists say no strong winds have been reported in the areas where tadpoles were found. One expert said gusts too weak to be picked up by observatories might have sucked up small quantities of water, along with a few unfortunate tadpoles. Ornithologists said it was too early too rule out their feathered friends.
While this isn’t a new phenomenon, it’s still a mysterious one, and similar events have been recorded throughout history – but famously drawn together by Charles Fort. While it’s usually explained away as being caused by a “waterspout” or a meterological phenomenon, no one actually knows why it happens. Fort himself recorded reports of falls of alabaster, ants, ashes, beef, beetle larvae, berries, bitumen, blood, butter, charcoal, china fragments (naturally vitrified?), cinders, coal, cobwebs, coins, crabs, crayfish, eels, fish, flesh, gelatinous matter, grain, hay, ice, iron balls, jelly fish, limestone, lizards, mud, mussels, oyster shells, periwinkles, quartz, resin, salt, sand, sandalwood, seeds, silk, snails, snakes, spawn, spiders, carved and shaped stones, turtles, and of course, toads and frogs. To name a few.
Wikipedia: Raining Animals
Blather articles on ‘falls’:
Fish Fall in Ireland’s West
Super Sargasso Surfin’