Out of the Blue

The onset of the monsoon brings about a fantastic transformation in the diversity of life on beaches. If you are a regular beach-stroller, you have probably noticed the myriad of creatures that start to appear around this time of year, many of them having been washed ashore by the very strong near-shore winds that bring the rain-loaded clouds. One such very pretty, curious-looking creature is the blue button (Porpita porpita).

SAIMG2
A blue button up close, with its gas-filled central disc fringed by tentacles

Blue buttons often wash up in some numbers just before and during the monsoon. However, a couple of weeks ago, I went to the beach one evening to see an unexpected, astonishing sight – from a distance, the edge along almost the entire 3 km stretch of beach looked a bottle-blue colour, dotted with white. When I got to the waterline, I saw that these were in fact millions upon millions of blue dollars lining the edge of the swash zone. And each wave was bringing in more and more of them. I rang a few friends, and we walked some distance of the beach to find that there were heaps of blue buttons everywhere (with each wave, they were literally piling up at the waterline).

SAIMG4
Blue buttons at the waterline on Karwar beach (the small black specks are tar balls, which also wash up on beaches during the monsoon)

I have seen mass beachings of blue buttons in the past, but this was astounding. The numbers were beyond anything I had seen before. The local fishermen had also never seen so many of them washing up simultaneously. Similar huge numbers had reportedly washed ashore in Mumbai around the same time.

SAIMG3
Blue buttons piled up at the waterline on Karwar beach

Blue buttons, along with their two equally curious-looking, curiously named relatives – the by-the-wind sailor Velella velella and the Indo-Pacific man o’ war Physalia utriculus (both pictured below) – tend to get blown ashore and stranded for the simple reason that they live at the mercy of winds, using a gas-filled float to stay at the water’s surface while their tentacles and digestive parts remain submerged. The latter two have a an erect ‘sail’ and a ‘crest’ on their floats respectively, giving them some control over which way they get blown. It has even been observed that depending on which part of the ocean they are in, they can orient themselves to get blown the ‘preferred’ way. Blue buttons, however, are devoid of any such sailing apparatus, and are more at the mercy of winds than the other two. All three of these get blown ashore with strong winds. The reason behind this particular beaching of unusually large numbers of blue buttons, however, remains unknown. In other parts of the world, such mass strandings are known to happen every 3 to 6 years, when oceanic winds go erratic.

4
By-the-wind sailor (L) and Indo-Pacific man o’ war (R) – Close-up views of the float with the ‘sail/crest’ (main pictures) and entire specimens (insets)

Although they look like jellyfish and are indeed related to them, these are not true jellyfish. Perhaps the most fascinating thing about them (from a biological perspective) is that each unit that appears to be a single animal – for example, one blue button – is not truly a single animal; it is a complex colony of several, each of which is called a ‘zooid’. The coin-sized central disc, which contains gas-filled tubes that keep the colony afloat, is one zooid. The digestive apparatus, which lies under the disc, is another set of multiple zooids. The blue tentacles bordering the disc, some of which serve to sting enemies and some to capture tiny prey, are yet another set of many zooids. A single blue button larva, over the course of its development, divides into several zooids, which stay together as a colony and function as a unit. They live and function in such a degree of coordination that it is actually hard to believe the whole thing is not one single animal.

This means one more thing – the apparent death of these creatures once they wash ashore may not be what it seems. Certain individuals of the colony can remain alive and active for a long time until they ultimately dry out. This is especially true of the stinging tentacles – we were warned that walking barefoot on the blue button-covered beach would ultimately make the soles of our feet itch from all the little stings. The stings of the blue button and by-the-wind sailor are very mild and can barely be felt, but the man o’ war really lives up to its name – its stings can cause severe pain and swelling, often with some punishing nausea and headaches added (another species, the Portuguese man o’ war, can even kill a person with its stings). So the usual wildlife-watching rule applies here: Don’t touch.

One may occasionally find discoloured or oddly-coloured blue buttons on the beach, such as this yellow one I came across in Goa last year. Speculation and some discussion point to the possibility of the blue proteins breaking down at high temperatures (when beached) releasing yellow compounds, giving the creature an overall yellow colour. But then, the reason these yellow ones are so rare seems to remain a mystery (I only ever saw one in Goa last season, and even during this extreme mass beaching in Karwar, we found only four or five yellow ones among the millions of blue buttons).

SAIMGf1
An unusual yellow Porpita

 

It has been years since I first saw a blue button, and I have seen them very often since, but this intriguing critter still holds its share of mysteries that I haven’t managed to find answers to. It remains one of the many marine organisms that I continue to find very fascinating, and one that continues to make those beach walks worth the effort!

 

 

Advertisements

3 thoughts on “Out of the Blue

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s