Wednesday, January 26, 2011

Changi Over Three Days

We conducted a seashore ecology lesson for some secondary school girls over three days last week from 19-21 Jan 2011. The tide was not really very low, but we still managed to see a number of interesting stuff.

Here are some of the things we saw:

On the first day, I spotted a dead Ghost Crab near the shelter. Ghost crabs generally are more active at night, when there are fewer aerial predators.

At the rocky shore area, we looked under some of the rocks, and found a few Stone Crabs and Porcelain Crabs.

Down at the sandy shore, the Sand Star was just slowly emerging from the sand, as it got cooler and darker.

Several Moon Snails were spotted, prowling just underneath the sand, seeking for smaller snails and clams to feed on.

There were many Sand Dollars too. It can be rather difficult for people new to seashore exploration to spot these animals, as they usually hide just beneath the sand.

There were only a few Salmacis Sea Urchin. This sea urchin can stick algae, sea shells and other stuff on it for camouflage.

And our seeker actually found us 2 living watering pot shell!

The Pink Thorny Sea Cucumber was as abundant as usual.

Several of this little Translucent Sea Cucumber were spotted.

As it got darker, other bigger sea cucumbers started emerging from the sand. Still not quite sure what species is this.

And I also found a few Notable Sea Cucumbers!

The students found this poor Pebble Crab that had lost most of its legs.

Moon Crabs are another group of crabs that are more active at night, though we can see them sometimes in the day too.

Saw some markings in the sand, and on uncovering the sand, I found this pretty Olive Snail.

LK found this snail which I don't know the species.

We were really lucky that the lesson went on smoothly and the weather held, despite it being the monsoon season at the moment! :)

Sunday, January 23, 2011

Project Semakau Survey on 22 Jan 2011

We are back on Semakau again to survey the intertidal life on the island under Project Semakau! There were lots of sandflies and mosquitoes this time round - not sure if it's due to the large pools of water in the forest due to the monsoon rain. Fortunately, weather was fine though there were lots of dark clouds before we started the survey.

For this survey, I did a zone on my own.

Right at the start of the zone, I saw an Api-api Jambu (Avicennia marina) tree growing on the rocks! This mangrove plant is critically endangered in Singapore, though there's a good population on Semakau.

At the rocky area, I also found 2 Dolphin Snails (Angaria delphinus). These snails can sometimes be seen on some of our rocky shores.

There was also a Burnt Murex (Chicoreus brunneus). This snail feeds on clams by secreting an acid to soften the shell before creating a hole to access the meat using a tongue-like structure called a radula.

There were plenty of small little hermit crabs which I had no idea what species they were.

Tonight was a snaky night, as we saw quite a few Dog-faced Water Snakes (Cerberus rynchops). These snakes feed on fishes, and got their common name from the fact that the side profile of their heads resemble dog heads (with some imagination).

Moving on to the sandy shore, I found a Galloping Sand Star (Stellaster equestris) again!

And this was also the first time I saw an live snail at Semakau! Forgot the species name, so guess will have to check with the expert again in office :P

I also found a Marginate Conch (Strombus marginatus) which I have not seen on Semakau for quite some time. Somehow this snail appear to be seasonally abundant. Used to find quite a number of them on our northern shores and Semakau for a while, but hardly see them these days.

I saw a littel black object moving around among the rubble, and found that it was a Sponge Crab (Cryptodromia sp.)! This species often carries small pieces of sponge or ascidian to camouflage it.

The first slug of the day - Bohol's Nudibranch (Discodoris boholiensis)! Saw 2 of them on this trip.

There was also a huge Mangrove Horseshoe Crab (Carcinoscorpius rotundicauda), unlike the usual smaller ones we had been regularly seeing. There are 2 species of horseshoe crabs in local waters. To differentiate them, run your finger gently over the top of the tail. If it feels serrated and spiky, it's the coastal horseshoe crab. If it feels smooth, then it's the mangrove species.

There were also a few of these huge Synaptid Sea Cucumbers (Opheodesoma sp.) among the seagrass. Each was more than a metre long!

Wai Kit and Edmund found this very pretty Forskal's Sidegill Slug (Pleurobranchus forskalii).

The Denison's Nudibranch (Dendrodoris denisoni) appeared to be in season, and we saw quite a few of them.

Here's another one. You can see that the appearance of this nudibranch varies quite a bit.

This Striped Ribbon Worms (Baseodiscus quinquelineatus) was spotted among the seagrass too.

And less than a metre away was this juvenile Knobbly Sea Star (Protoreaster nodosus)! Semakau is one of the few places in Singapore where you can find good population of juvenile Knobbly Sea Stars - a good indication that they are reproducing well on this island!

And also within a metre of the ribbon worm was this Pseudobiceros uniarborensis flatworm. Along the way, I spotted many of them among the seagrass!

The other groups found a few brittle stars too!

Here's a closer look of the central disc.

And here's the underside, with lots of tiny tube feet! Hopefully the brittle star expert from Japan will be able to tell us the species when he's here after Chinese New Year.

And I spotted this little Red Shrimp (Processa sp.) among the seagrass. Sammy the shrimp expert will certainly be happy to see this!

Glad that it was again a great day with nice sightings!

Sunday, January 02, 2011

Semakau Walk on 2 Jan 2011

Today, we had our very first Semakau trip for 2011! This trip is special, because it was meant for active Project Semakau volunteers to bring their friends and family to learn more about what they do for this project.

Despite the rain and we had to end the intertidal walk within an hour, we had lots of fun and several nice sightings for the year's first Semakau trip!

Here are some of the volunteers with their guests.

As we entered the intertidal area, we were immediately greeted with hundreds of Hairy Sea Hares (Bursatella leachii).

Many of them were in the process of burrowing into the sand. I did not see any mating chains though.

However, we did see the egg ribbons laid by the sea hares.

There was a little Mangrove Horseshoe Crab (Carcinoscorpius rotundicauda) at the sandy shore area. Horseshoe crabs are very ancient animals, and they have been around even before the dinosaurs time!

I saw a Giant Carpet Anemone (Stichodactyla gigantea), but could not find any anemonefish or anemone shrimps.

The Tape Seagrass (Enhalus acoroides) was blooming! In this photo, you can see the both the female flower and the male flowers. The latter are the small white bits stuck in the middle of the flower, and there's one on floating to the right side of the female flower too.

Several small Noble Volutes (Cymbiola nobilis) were found. I saw a few matured ones laying eggs too.

This Spider Conch (Lambis lambis) has a hard coral growing on its shell, which probably helps the snail to camouflage better.

And the highlight of every Semakau trip must be the Knobbly Sea Stars (Protoreaster nodosus)! We found several juveniles, each not more that 10cm wide.

One of the juveniles even had 6 arms!

We later found a huge one, about 30cm wide.

But that's when the sky started darkening and soon, it started raining.

We had to end the walk for safety reasons, but I was sure it was still a very interesting walk for most of the participants!