The black nettle jellyfish are back in San Diego Bay. Their real name is Chrysaora achlyos, and you should count yourself lucky if you ever even seen one as it wasn't until 1997 that they were designated as a specie.
They tend to coincide with red tides, and swarms of the black nettles seem to happen every few years. About 200 people a day got stung along the San Diego county coastline the last time these weird creatures from the deep showed up. They mysteriously show up, then quickly vanish again.
While not as nasty as the Portugese man o' war, (which isn't actually a jellyfish at all), black nettles have millions of "nematocysts", tiny little venom pods that when touched by you (or a fish) release.
For the full details on jellyfish sting management, check out Diver's Alert Network:
1) Flush with tons of sea water. Get any residual stingers off.
2) Get some vinegar on there.
3) Immerse in warm/hot water to neutralize any remaining badness.
So as your friendly neighborhood sea captain, give some extra thought to your time in the water this summer. It's certainly not a reason to avoid going to the beach or hopping in the drink, but more just some things to consider so you know what they are, what they can do, and what you can do about them.
The sting from a black nettle will vanish in under an hour if you don't do anything at all, but if you'll be spending time at the beach especially with kids, consider bringing some white vinegar even if just in a little spray bottle. It's a cheap and effective way to knock down a jellyfish sting in no time flat.
I took the pictures with my GoPro, and then popped a little video so you can see what they look like underwater. Be safe bros!