Saturday, December 27, 2008

Discovery @ Sultan Shoal on 27 Dec 2008

Eighty-third Discovery Posting:

First of all, most people would be unfamiliar with Sultan Shoal (like me), so here's a short introduction of it I got from Wikipedia (

"The Sultan Shoal Lighthouse (苏丹浅滩灯塔) is a lighthouse located on the island of Sultan Shoal in the Western Anchorage of Singapore about 8 km south of the western tip of Singapore Island. The lighthouse tower is painted white while the keeper's house roof is red and is of a mixture of Oriental and Victorian design.

The island also houses two staff chalets which is managed by the Port Authority of Singapore. "

So, here a picture of the Sultan Shoal Lighthouse (picture below).
A closer look at the lighthouse tower suggests that it was built in 1895!

Anyway, besides taking a look at the lighthouse. Our purpose of going there was also to check out what kind of marine life resides on the island.

I did got a little shock when I first saw the lagoon on the island. It was an enclosed lagoon, save for the little holes at two different sides of the enclosure to ensure water circulation.

However, this man-made structure or swimming pool did not prevent marine life from finding their way into the lagoon. Here's first 'discovery', some nerites which had beautiful shells (picture below).
Discovery Note:
1. They are commonly found on rocky shores.
2. Further studies of them could be done (to find new species), as a recent paper in 2008 based on 31 survey sites over a period of 10 years yielded 19 species with 6 new discovered species for Singapore.
3. Do be careful when you walk around pools and small rocks, as you might be stepping on the eggs of nerites (small white egg capsules).
4. Read more about nerites @

As there was not much life to be seen on the exposed shore, we decided to turn over some rocks around the area as some marine animals like to hide under them to prevent themselves from suffering from dessication (the process of drying out). And that's where the second 'discovery' was spotted. Can you spot it (picture below)?It is a sponge crab and here is its underside (picture below).
Discovery Note:
1. They are called sponge crabs as they usually have a living sponge on its top carapace.
2. It is not born together with the sponge if you are wondering. The crab uses its pincers to snap out a cap out of a living sponge to fit it over its body.
3. The purpose of this is for camouflage and protection from its predators (since sponges usually leaves a 'bad' taste).
4. To read more about it, visit

And there was even a first sighting! A electric blue fiddler crab (Uca tetragonon) (picture below)! This was found by Prof Peter Ng, the crab expert who was also with us. Third 'discovery'! Discovery Note:
1. These crabs are an important marker or indicator to tell us that there are healthy reefs around.

And also for the first time, I managed to capture a goby and snapping shrimp from the same burrow! Fourth 'discovery' (picture below).
Discovery Note:
1. They share a "you scratch my back, i scratch your back" relationship in this situation.
2. The goby is in charge of looking out for danger while the shrimp is in charge of digging and maintaining their shared burrow.

And for the last, fifth 'discovery' of this entry. Here is a feather star (picture below)!Discovery Note:
1. These creatures are more commonly seen during diving trips compared to Inter-tidal walks.
2. Like brittle stars, they are fragile and their arms may break easily, so either handle them with extreme care or don't handle them at all. =)
3. If you look closely at feather stars, you may sometimes find a well-camouflaged crab or shrimp living on it. So always take many looks when you see one of these.
4. Read more about them @

Before I end this post, here's a look at the lighthouse again (picture below).
At of course, thanks to LK for making this trip possible and many friends who went and made the trip fun filling! =D

Extra: Read and see more of the organisams we saw during this trip on
a) KS's blog entry
b) Tidechaser's blog entry
c) Manta's blog entry

Sunday, December 14, 2008

Discovery @ St. John Island on 13 Dec 2008

Eighty-Second Discovery Posting:

Together with a group of friends, we explored the little patch of mangroves and the inter-tidal zone of St. John Island.

One great find, the first 'discovery' for this entry is the rarely seen Api-api Jambu (Avicennia marina). Here's a photo of it's fruit (picture below).
Discovery Note:
1. The timber for this tree can be used for firewood.
2. This is the rarest of all Api-api found in Singapore!
3. Read more about it on

Not wanting to miss the low tide for the evening, we immediately moved towards the inter-tidal zone after a short look at the mangroves. And along the sandy beaches, we saw a whole army of soldier crabs! Here's one of them (picture below), second 'discovery'.
Discovery Note:
1. They are quite shy. So if you want a close look at them. You will have to wait silently next to a hole of it and not make any movement if possible.
2. Unlike most crabs which are capable of moving only sideways, the soldier crab can move forwards and backwards as well!
3. Read more about the soldier crab @

We also spotted a number of fiddler crabs in the area. Third 'discovery' is one of them (picture below).
Discovery Note:
1. Fiddler crabs are characterised by their one oversized pincer.
2. Do take note that only the males have this oversized pincer.
3. The purpose of it is to attract mates and sometimes used to 'fight' for terriotry.
4. However, the oversized pincer is useless for feeding, they use their normal-sized (small) pincers to feed.
5. Female fiddler crabs have TWO pincers (small-ones), thus they can feed faster than males.
6. Find out more about the orange fiddler crabs on the wild facts site:

And just near the upper reaches of the sandy shore, we manage to find a few land hermit crabs as well! Fourth 'discovery' is one individual (picture below).Discovery Note:
1. As their name suggests, they are more likely to be found on land, more specifically, the upper shores where they can avoid the waters from high tide.
2. As they have adopted to life out of water, they will drown if kept underwater.
3. It breathes by using special gill chambers which are large and retains water well. This means that they have to go for a occasional dip in rainwater or the sea to keep the gill chambers wet.
4. Read more about the land hermit crab @

Two related crabs was also spotted amongst the rocks of the inter-tidal zone. The brown egg crab and red egg crab (pictures below). Fifth and sixth 'discovery'.Discovery Note:
1. If you are ever out of food and stuck on an island, never eat this kind of crab, as they are poisonous and their toxins are not destroyed by cooking.
2. Read more about the red-egg crab @

If you have noticed, I have written about a few crustaceans already and here's one more, the snapping shrimp, seventh 'discovery' (picture below).Discovery Note:
1. If you have walked around the inter-tidal zones and wondered what is making a 'click' or snapping sound, this is it!
2. They make this sound to stun prey, ward off predators or intimidate other snapping shrimps.
3. Read more about them @

If you are interested to learn more about crustaceans, visit to have a general idea of what they are.

Eighth 'discovery' is an onch which can be found on rocks on the high shores (picture below).
Discovery Note:
1. Although located near the seas, they actually belong to the same group of animals as land snails!
2. For breathing, they have lungs instead of gills! Thus at high tide, they burrow into mud or sand and trap an air bubble to breathe from.
3. They are actually quite common but well camouflaged, so take a closer look next time you pass a rock near the seas during low-tide.
4. Read more about them @

R also found an seldomly seen nudibranch. This should be a spotted foot nudibranch (Discodoris lilacina). Ninth 'discovery' (picture below). Discovery Note:
1. See more pictures of this sea slug @

The tenth 'discovery' of the day and the last one for this entry is blue-spotted fantail ray spotted by G (picture below).Discovery Note:
1. The position of the eyes allows the blue spot stingray to see almost behind it.
2. The gills and mouth are found on the underside of the body.
3. It doesn't really have teeth—instead, the mouth is outfitted with two food-crushing plates.
4. Rays dart away when they sense trouble approaching. When caught off guard, these fish fend off predators with a flick of the tail, which is equipped with two venomous spines. Since its tail is so long, the blue spot stingray can even strike at animals directly in front of it.
5. The large tail spine of the blue spot stingray is dangerous and even deadly. The barbs in the tail are so large; people have bled to death from a sting.
6. Read more about them @
Another nice trip with the company of friends and creatures of the sea, thanks to LK for organising this trip. ^^