04 June 2011

Lots of sexangula on Changi!

A large number of 'seedlings' of this uncommon mangrove tree washed up on Changi!
Today, the tide didn't get as low as predicted. Still, some interesting marine sightings, but I was mainly overwhelmed by the huge number of propagules of this uncommon mangrove tree washed up on the shore.

Tumu berau (Bruguiera sexangula) is uncommon throughout its global range. In Singapore, there are two trees on Pulau Tekong, and two at Sungei Buloh. It is also being replanted at Chek Jawa, Pulau Ubin and at Pasir Ris Park. Here's a photo of a flowering planted Tumu berau at Chek Jawa.
Tumu berau (Bruguiera sexangula)
Today, Tumu berau propagules seemed to outnumber the other kinds of propagules washed up on the beach. Where did all these propagules come from? Facing the Johor River mouth and Pulau Ubin and Pulau Tekong (which has lots of mangroves), all kinds of interesting mangrove propagules land on Changi with the tides. Wow!

Today, a rather large team visited in expectation of a good long low tide. Alas, the tide didn't go as low as expected. By sunrise, not much of the shore was exposed. But that's ok. When the tide is not so low, I get a chance to look more closely at common animals and plants!
There were as usual, lots of cerianthids (Order Ceriantharia). But I saw this one that was a bit different. It seems to have yellow bendy 'elbows' on its tentacles. Something I haven't noticed before.
Here's a closer look at the bendy 'elbows' on the cerianthid. Hmm...I have no idea what is going on!
I also looked closer at the inside of a Peachia anemone (Peachia sp.). This anemone usually has three knobs in the centre of its mouth. Today, I realise the knobs are at the tip of what seems to be a cylindrical thing in its mouth. Wow, that's just weird.
I saw several small to medium-sized Haddon's carpet anemones (Stichodactyla haddoni). Some were crawling with tiny Carpet anemone shrimps (Periclimenes sp.)! I tried to take a close up of some of them today.
Among the seagrasses, there were still many Pink sand dollars (Peronella lesueuri). It's still a mystery why they recently became so common here. I also saw some Cake sand dollars (Arachnoides placenta).
I came across several large White sea urchins (Salmacis sp.). These animals carry all kinds of things. This particular one was carrying a mangrove propagule and an empty worm tube!
I saw four of these Remarkable sea cucumbers (Holothoria notabilis). So far, I've also only seen them at Chek Jawa, Cyrene Reef and Kusu Island. So Changi is one of the special places for this indeed interesting animal.
I didn't see many sea stars today. I only saw one small Cake star (Anthenea aspera) and several small Plain sand stars (Astropecten sp.). I didn't come across any Biscuit sea stars (Goniodiscaster scaber).
A hard surface is hard to find in a seagrass meadow. And it is well appreciated by all kinds of animals. This dead Fan clam (Family Pinnidae) is a handy home for a pair of Thorny sea cucumbers (Colochirus quadrangularis), and a little Swimming crab (Family Portunidae).
The seagrass meadows generally seemed alright with lush growths of the usual species we see here. But on the high shores, some parts of the seagrasses had brownish scum. I don't know what this means.
I was excited to see this small shell of a Baler volute (Melo melo). But it was already dead. Nevertheless, a small Striped hermit crab (Clibanarius infraspinatus) has taken over the empty shell. Nothing is wasted on the shore! So please don't take any shells home!
I did also see one Olive snail (Family Olividae), plenty of Window pane shells (Placuna sp.) of all sizes from tiny to super large. There were still lots of Sea pencils, and many buried Smooth sea cucumbers and Ball sea cucumbers (Phyllophorus sp.). The rest of the team found the Japanese bonnet snail (Semicassis bisulcatum) we saw on our last trip to Changi. And many other interesting sightings too.

At dawn, a small family group came to explore the shore. How nice to see parents bringing their kids to see our shores. A pity that the tide was so high today.
More low tide trips ahead of us! Tomorrow, we're going out with Dr Dahpne to look at sea anemones! Hurray!

Posts by others on the trip
  • Jerome on facebook with lots of colourful marine life including Leopard whipray!
  • James with lots of great close ups of intriguing marine creatures.

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