22 July 2009

Nem Hunt Day 3: Changi

Today the Anemone Army goes to Changi: the Anemone Goldmine!
We purposely dedicate the longest and super lowest tide to a seemingly boring stretch of Changi shore. Because it is just teeming with anemones. And we worked very hard to cover this small stretch thoroughly.

Here, we find spectacular anemones such as the one above that looks like it is made of blown glass. It stings painfully according to Dr Daphne, and no one is ready to find out just how painfully. Another interesting detail she shares is that the anemone drops off its tentacles (which continue to sting) and these break off along the black rings at the base of the tentacles! Dr Daphne also confirmed that these animals are Doflenia sp. We found four of these anemones this morning!

Another anemone that is common on this stretch of Changi but less so elsewhere, is this yet-to-be-identified anemone that has red pimples on its body column and fat banded tentacles with a pair of maroon spots near the mouth. I call it the Tiger anemone. Dr Daphne calls it the Strawberry anemone because of the red pimples.
Dr Daphne is astounded by this anemone and says she will need to work on it some more to find out exactly what it is. Although this sea anemone is quite common here, it may be something new to science! Simply because it has never been properly studied before.

We are also keen to observe the Peachia anemones (Peachia sp.) which are tiny and quite abundant on this shore. But these animals are tenacious and it's hard to take a closer look at them as they quickly contract deep into the soft ground.
We also come across this large sea anemone in the silty sand. I've seen these stuck to shells occupied by hermit crabs. But today, the one we found was stuck to a living snail!
There was another little anemone that looked similar to the big one above, but it was much more colourful. And it too was attached to a living snail.
Dr Daphne shared how studies suggested that hermit crabs actively attached sea anemones to their shells when there's menacing octopuses around. And indeed today, octopuses were seen on the seagrass meadows.
The shore also had many Stichodactyla tapetum, which are miniature versions of the Haddon's carpet anemones (Stichodactyla haddoni), also common on this shore. I saw this Haddon's carpet anemone with 'spots'.
A closer look reveals that some of the tentacles were inflated, and sticking out above the rest. I'm not sure what is going on. There were also little carpet anemone shrimps on the anemone, which is not unusual.
Chay Hoon also found lots of Edwardsids, a kind of tiny sea anemone. Dr Daphne is amazed as the animals had nearly transparent tentacles. But we are not surprised as we know Chay Hoon has amazing eyes to spot the impossible creatures. I didn't take photos of these as I was far away, but I hope James did. They sound quite exciting.

As usual, despite our anemone focus, we couldn't help but stumble across other amazing marine life on this living shore.

The Peacock anemones (Order Ceriantharia) are NOT true sea anemones (Order Actiniaria). Peacock anemones are burrowers and are thus abundant on this soft silty shore. The one in the left most photo one had more elegant tentacles, while the other two are the more commonly seen peacock anemones.
Little black Phoronid worms (Phylum Phoronida) are often found living with peacock anemones. And today, I saw one peacock anemone encircled by a ring of these worms. Phoronid worms have a long, worm-like unsegmented body topped by a pair of feathery spiralling tentacles.
Here's a closer look at the worms. In some phoronid worms, the body penetrates the tissues of the peacock anemone but the phoronid worm is not parasitic and does not absorb nutrients from the peacock anemone directly. Knowing this, it's quite creepy to see so many Phoronid worms around the peacock anemone above.
The soft silty shore is also a great place for other burrowing cnidarians such as sea pens (Order Pennatulacea). Sea pens are colonial animals, each a collection of polyps. I haven't seen a Slender sea pen (Virgularia sp.) for a while, so it was nice to see this one with orange secondary polyps arranged on white leaf-like structures on the central primary polyp.
There were also many Flowery sea pens (Family Veretillidae). Out of water, with their flowery secondary polyps retracted into the sausage like primary polyp, the colony may be mistaken for a sea cucumber or uprooted sea anemone. I got tricked a few times by these.
I didn't manage to get to the corner of Changi where the glorious sea fans are found and which Kok Sheng explored so thoroughly. The opposite corner only had a few sea fans like the orange one shaped like a candelabra. And on the large rocks were all kinds of encrusting marine life, which are preyed upon by animals such as this Blue spotted flatworm (cf Pseudoceros indicus).

Like many of our Northern shores, Changi is a great place to find echinoderms!

But this morning, the stars I saw were few and small. There was one small Biscuit sea star (Goniodiscaster scaber) and some Plain sand stars (Astropecten sp.).
But it was a delight to come across a little Luidia sand star (Luidia sp.). The upper surface of the body is covered with structures that look like tiny stars. This sea star is not seen very often.
There were, however, a lot of brittle stars crawling about among the seagrasses. The ones with flat arms were quite large and active. But there were also tiny little ones, and much larger ones hidden in holes and crevices.
In deeper waters (which were surprisingly clear today) there were clusters of Black sea urchins (Temnopleurus sp.).
Just as we were going home, Chay Hoon found a small and rather beat up Pink sand dollar (Peronella lesueuri)! Wow! So far, we've only seen these at Pulau Sekudu!
I didn't really pay attention to fishes today. But there were quite a few pipefishes among the seagrasses.
No trip to Changi is complete without some slug sightings! Today, the seagrasses were dotted with little hairy seahares (Bursatella leachii) (photo on the left).
And I saw one Bushy nudibranch (Polybranchia orientalis) which has sticky leaf-like appendages that drop off when the animal is alarmed. Chay Hoon said they are probably in season now as she saw some at Pulau Sekudu yesterday.

It's been quite an exciting if exhausting series of trips, with midnight to 2am wake up calls three days in a row. The Anemone Army is getting a little tired, but The Hunt continues!

The Anemone Army next goes to our Southern shores. Tomorrow, a 4am wake up call. Great! I get to sleep in.

More posts about this trip
Changi - "Peering into the sand and grass" by James on his Singapore Nature blog

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