This is the exact question I'd be asking if I hadn't googled to find out what on earth I saw last week!
I went down to the beach and there were heaps of 'airless bluebottles' washed up. That's what I called them as I took photos and puzzled over what the heck they were (you know, as I so often do!)
There were a few 'aired' bluebottles there, but they were far out-numbered by the airless ones.
|Velellas with a Bluebottle
Normal blue bottles have a stretch of tentacles, or a wound up ball if them (the bright blue, stinging part), and the others didn't have that. They had a blue tinge of colour but no tentacles that I could see. But I wasn't getting too close as I had no clue if they stung or not - and if they did, woudl it be worse than the regular blue bottles? I found out later they don't sting...but I wasn't testing it out!
When I googled 'airless bluebottles Australia' I came across newspaper article written a few days earlier on the NSW North Coast, describing exactly what I was seeing on the south coast. The fab journo had identified the mystery buggers for me. Then I went to my books with a name, so much easier than going with nothing.
|Lots of Velellas washed up
The Australian Museum also mentions them here, about halfway down the page, and also calls them By-The-Wind Sailors.
Then I found a reference on a CSIRO website, here, which also mentions Purple Bubble-raft Snails (also on the beach on the same day and next week's wildlife post).
The CSIRO site says this,
"Out in the open ocean where blue bottles live, each armada (the collective term for blue bottles) has both left and right handed forms. But when a breeze kicks up and drives them toward shore, only those with the crest facing the right direction to catch that particular breeze will sail toward their death. It seems that this is nature’s way of ensuring that some survive.
Blue bottles are strikingly beautiful. The air bladder is pearly blue, while the tentacles are intense peacock blue or dark teal. This shade of blue is common in animals that live at the air-water interface, and is thought to protect them from UV damage and possibly aid in camouflage.
Other creatures that live in this unusual habitat include the By-the-wind Sailor (Velella velella), the exquisitely beautiful Purple Bubble-raft Snails (Janthina sp.), and the highly unusual Sea Lizards (Glaucus and Glaucilla), which are actually sea slugs that consume and store undischarged stinging cells from jellyfish such as blue bottles for their own defence."
As much as I've searched for the beautiful Glaucus, I've never found one. But that day on the beach, all the others were present. I guess I keep searching!
Have you ever seen Velellas?