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. ^^

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