Monday, August 17, 2009

Beachcombing finds II: Blue bottle, violet sea snail, by-the-wind sailor & blue button

As I mentioned in my last post, I found heaps of blue bottles (Physalia utriculus (?)) that were washed ashore. I saw the same thing at South Cottesloe as well as the South Beach, Fremantle.

Hundreds and hundreds of blue bottles were washed ashore, marking the high tide line.

They are reasons why you don't want to walk on the beach bare-footed. They have stinging cells on their tentacles (red arrows).

I got stung anyway, not because I was bare-footed but somehow one of them got caught in my sandal when the tide came in. It was painful but bearable. And thankfully, there's no swelling or anything like that. By the way, its tentacle seemed quite sticky and it took a bit of effort to get it off my sandal.

If you look carefully amid the blue bottles, you might find the by-the-wind sailor (Vellela vellela) (blue arrow) and violet sea snail (Janthina janthina) (red arrow). The violet sea snail, which I thought would be rather harmless, is actually a predator of blue bottles and by-the-wind sailors (see here).

This blue bottle has a tentacle 1-1.5 m in length. It must be a nasty experience to come into contact with one while swimming. The red arrow indicates the float. The air in the float may contain rather high levels of carbon monoxide, which the blue bottle produces! Amazing. Steve Reynolds has written two interesting articles about blue bottles in the Marine Life Society of South Australia Newsletter (October 2008; March 2009).

The Mote Marine Laboratory website also has an article about how they keep blue bottles in a tank so that their floats won't dry up too fast and their tentacles won't just stick to everything they touch.

Lovely violet sea snail! The raft of mucus bubbles helps the animal stays afloat upside down. Preying on floating creatures like bluebottles is also a way it helps itself stays afloat. How "clever" - if that means anything to a sea snail : )

This by-the-wind sailor is about 2 cm across. The red arrow points at the sail. The blue arrow points at the disc which contains many small air chambers to help the animal stay afloat.

This is the first time I saw some blue buttons (Porpita species) with the disc (blue arrow) and the tentacles (red arrow) still intact. A Porpita with its tentacles fully extended is just incredibly beautiful ( see here). The first time I saw the dead ones which had lost their tentacles, I thought they were some dress buttons!

My previous posts about the Blue Layer:
The Blue Layer - Blue bottle, by-the-wind sailor, violet shell
The Blue Layer - Sea lizard


glhopman said...

wow, these are some amazing finds. It seems that everything that lives in the "blue layer" is a remarkable creature. Have you found any of the by-the-wind sailors with their tentacles still attached? also, did you keep the beautiful shell of that violet sea snail? thanks for the post, i love seeing these amazing animals.

Tsun-Thai Chai said...

Great to know that you like the post. What I find so amazing is that there is this blue layer in the sea consisting of small, bluish, floating animals.

Most of the by-the-wind sailors I saw were dry and dead so I didn't really see any tentacles on them. Already degraded maybe. About keeping the violet sea snails - no I didn't. You see, Cottesloe is a marine park. So I will have to stick to the rules and not take anything home, except photos.


Tsun-Thai Chai said...

"The creatures of the blue layer or 'blue armada' drift across our ocean in huge surface floating clouds, feeding on each other and the vast array of oceanic plankton they pass across on their journey."

MESA's The Blue Layer

Denis Wilson said...

Lovely post of some truly fascinating creatures, Chai.
Well done.
The "Blue Buttons" are amazing.

mick said...

Great photos and descriptions! Your photos show the blue color especially well! This post was especially interesting as I had just seen Violet Snails and By-the-wind Sailors for the first time - at Inskip Point about a week ago. (Thanks to Denis for reminding me to come and visit here!)

Tsun-Thai Chai said...

Hi Denis and Mick,

Good to know that you liked the post.
These animals are truly amazing.


Tsun-Thai Chai said...

Hi Denis, I just looked at Mick's post on the violet snail and by-the-wind sailor. I just realized that you have done some advertising for me. Thanks!

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