A marine mystery solved (and a bit about birds) « Why Evolution Is True

There are a million mysteries in the Naked City of Biology, and some of them get solved. This is one of them, taken from the Japanese culture siteSpoon & Tamago. It’s described in the post “The deep sea mystery circle—a love story  “

Several decades ago, a Japanese “salary man” named Yoji Ookata quit his office job to pursue his real love—underwater photography.  Recently, diving 80 feet down off the island of Amami Oshima   (one of the Amami islands between Japan and Taiwan), Ookata saw something that nobody had ever seen before. It was a large, radially symmetrical pattern in the sand, and looked like this (note underwater camera for scale):

It’s a fish! Or, rather, a single small male pufferfish who digs the structure in the sand:

Here it is digging:

To close, here is an elaborate bower built by the male satin bowerbird  ,Ptilonorhynchus violaceus.  Their bowers are often decorated with objects purloined from humans, and the females (ergo the males) seem to have a preference for blue. Experiments show that the females prefer to mate with males whose bowers are decorated more elaborately.

Females enter and inspect the bower before mating, and the males also perform an elaborate behavioral display as well.  Here’s the artist and the consumer. Note the sexual dimorphism in color, itself an indication that sexual selection is going on here:

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