A happy day on Changi

6am and it's a super low tide on Changi! The early morning sandy shore was crawling with tiny hermit crabs and tiny little sand stars (Astropecten sp.).The hermit crabs obviously didn't quite like the sand stars. Sand stars are carnivorous and generally eat mainly snails and clams. But these sand stars are known to be unfussy about what they eat.Every now and then, a little hermit crab would nip at the tips of the sea star's arms. Then quickly run away!Like elsewhere, some of these sand stars had tiny little white snails on their arms. These are probably parasitic snails. Must be awful not being able to pick them off your arms.Another burrowing snail sometimes seen on Changi is this Olive snail (Family Olividae). This particular one seem to have survived a ferocious attack on its thick smooth shell. By a crab?The underside of the snail was still alright, and the animal itself seemed ok.

The seagrass meadows today seemed a little thin. There was also not much seaweed. There were plenty of large white sea urchins (Salmacis sp.) as well as many skeletons of these sea urchins. So perhaps the 'urchin season' is nearly at an end. There were also quite a lot of sand dollars (Arachnoides placenta).

There were many large carpet anemones but none I saw with anemone shrimps, not even tiny ones. Except for this one.Here's the big fat mama anemoneshrimp (Preclimines brevicarpalis).And the smaller, more transparent papa shrimp.

We also saw a large glass anemone and the hermit crabs had little anemones on their shells. But not many other kinds of sea anemones. In fact, there were also very few peacock anemones and sea pens. This is rather odd as this shore is usually teaming with these animals.

Kok Sheng had asked us to check on the situation with the Button snails (Umbonium vestiarum). And we found a patch of these tiny little snails!I've often been annoyed that these snails tend to float up when we try to take a closer look at them. Makes it difficult to photograph them. Siti mentioned that in some snails, the first chamber is used in flotation. We also noticed that the floating snails tended to stick together, forming 'rafts'.

Dr Dan remarked earlier that this is an important behavioural aspect. This may allow these snails to disperse to new areas quickly. Indeed, as I thought about it some more, it may also be a way for them to escape from predators. If they are dug up while submerged, they float straight up away from the ground thus escaping nasty predatory snails and other animals that can't swim.As we observed the raft of snails, one by one, the snails would sink and quickly burrow back into the sand. The snails have tiny little eyes on stalks, and a long leaf-like foot. Amazing!

A first-time encounter for me was this strange black fan worm with white spots on its feathery tentacles.And what a marvellous surprise! Chay Hoon finds a feather star! A first time for me on Changi.Today we also came across the strange green sea star that was first mentioned in the manta blog in April and again in May. The big white patch is an injury to the sea star.Here's a closer look at the upper side. The big 'knobs' are made up of tiny bumps. Something had taken a nibble off the top of this poor sea star.And a look at the underside. It has pale pink tube feet with suckers at the tips. We have no idea what kind of sea star this is!

Besides the sand stars, we didn't see any other kind of sea stars on this shore. But there were lots of thorny sea cucumbers (Colochirus quadrangularis), buried ball sea cucumbers (Phyllophorus sp.) and smooth sea cucumbers, some warty sea cucumbers (Cercodemas anceps), one transparent sea cucumber (Paracaudina australis) and the strange beige sea cucumber that looks like sand.

The edible animals seemed particularly scarce today: no Sandfish sea cucumbers (Holothuria scabra), few Gong-gong (Strombus canius), few Fan shells (Pinna sp.), no horseshoe crabs.

There were lots of people out on the shore especially after sunrise.
Some were just looking around.
Some had plastic bags collecting stuff. I couldn't get to see what as they avoided me, but Siti saw someone with some Fan shells. I also came across piles of large Window-pane shells (Placuna sp.) that looked like someone collected them and then changed their minds. In the distance a man with a changkul digging for worms, probably for fishing.There was much fishing going on at the shore. We had to step over many lines strung out on the shore in the morning. And the team gathered some abandoned lines on the shore. There was also a group of fishermen on an inflatable boat off shore. Later in the morning, one went out into the incoming tide with a cast net.

There was also a big group camping on the shore, probably because tomorrow is a school holiday.Thus it was very heartening to come across one guy walking out onto the tidal flats to RETURN these two amazing snails! We asked if we could take photos of them and he let us have them.On the left, a large and living Bailer snail (Melo melo) and on the right, a lovely Noble volute (Cymbiola nobilis). Both these snails are listed among the threatened animals of Singapore due to habitat loss and over-collection.

From Ng, P. K. L. & Y. C. Wee, 1994. The Singapore Red Data Book: Threatened Plants and Animals of Singapore. The Bailer snail is "thought to have been exterminated from our waters, but a recent isolated sighting confirms their continued presence". While the Noble volute is "confined to the region, particularly Singapore and southern Peninsular Malaysia, presently uncommon on our reefs although abundant in the past".

The Bailer snail was very much alive, although it seemed a little slow. The Noble volute was perfectly fine. Our last encounter with someone collecting a Bailer snail had a less happy ending.After checking on the snails, Samson and HB took them far out into the water to release them. Hopefully, they will be safe from collectors.

What a wonderful way to end a great day out on Changi!

More about this trip and the Melo melo on the manta blog.