|Never gonna grow up|
This funky little fish species is a Southern Puffer Fish (Sphoeroides nephelus), which I find a great deal of fun.
First off, they're abundant at times in the Indian River, and they can be found easily in very shallow water, usually near rocks. This is because their food is mussels and barnacles, which they use a beaklike set of jaws to remove from the rocks and pretty much ingest whole.
Second, they're generally pretty slow and stupid fish, and they can often be coaxed or herded into a rocky cul-de-sac from which they can't escape easily, allowing them to be caught by hand with very little effort at all. I've even just grabbed them in open water.
But primarily, it's because their defensive mechanism is the classic inflation trick, and they're really good at it! Within 2-4 seconds of being caught, a Puffer can inflate bladders within their body, with water or air, to expand to many times their girth, taut as a balloon. On occasion they do so with the sound of a poorly-oiled air compressor, and not unexpectedly, when they're released they deflate with a distinctly flatulent sound. I still haven't grown up, so of course I find this remarkably entertaining.
The inflation probably serves them quite well in avoiding fates such as the one on this page, since hanging out in the shallows near rocks is not exactly the safest place for a fish to be. But that's not their only defense, from what I've heard — those jaws can deal a really nasty bite. They can't really turn their heads so avoiding them isn't difficult, but I'm still cautious.
Their eyes are pretty interesting too, having a reflective golden sheen to them when seen from above, and this probably helps with shielding them from sunlight in the shallows, since fish have no eyelids. Note also, in the middle image, how the gill opening just ahead of the pectoral fins has been closed off by a membrane while inflated.
My photo subject here showed some distinct, and very puzzling, scars on one side of his snout. My first thought was "octopus" but it really doesn't look right, and presently I suspect (and am open for correction) that they actually came from another Puffer.
During the summer, like stingrays, it didn't seem like a proper trip down to the river if I didn't see at least one of these guys, even if I left them alone in search of other subjects.