Wednesday, June 6, 2007

Adventure with Naked Hermit Crabs on 6 June 2007

Eighth Discovery Posting:

(Entry @ 8 June 2007: Managed to get the ID for the unknown nudibranch. Thanks CH!)
(Entry @ 7 June 2007: Added information about the polyp. Like to thank Ria for the info. thanks, Ria)

First of all, i apologize for the mistake made for the last discovery entry, the date should have been 5 June not 6 June. Must have been the excitement and tiredness from the walk yesterday. =p

Anyway, back to this entry.

This morning when we reached Sentosa, low hanging clouds enveloped the sky and the wind was blowing stronger than usual. It looked like it would rain anytime and everyone was hoping that the weather would hold and not rain.

Very soon, the participants arrived and with the weather in a stasis mode, we proceed to our different trails. Today, I was heading for the adventure trail with Ron being the head guide and Robert and Andy being hunter seekers cum co-guide.

As we descended upon the shore, Robert soon spotted a rare find. A ghost crab (picture below and First 'discovery') seen during daytime? Upon observation, we found that one of its pincers was caught onto a stray fishing line or net line. With some effort, Ron, Robert and Andy managed to free the crab and it 'disappeared' from sight with the first sight of 'freedom'.
Discovery Note:
1. These crabs are called ghosts because of their ability to disappear from sight almost instantly, scuttling at speeds up to 16 km per hour, while making sharp directional changes.
2. Ghost Crabs live in deep burrows above the waterline.
3. They come out of their burrows to feed at night.
4. They are known to eat small particles of dead plants, animals, algae and micro-organisms.

Although being so close to the city (picture below), we actually have shores filled with life.
These branching corals (picture below) were actually growing very well even being so near our city area. Second 'discovery' of the day also made me ponder about that if the development on Sentosa would rob us of these wonderful nature sights.

People have been talking about saving our forests, how about saving our corals too. They are forests also, the forest of the sea.
A closer up shot the corals (picture below)
Discovery Note:
1. Branching corals are characterized by having numerous branches, usually with secondary branches.

As we walked the shoreline, Ron pointed out some flora which were along the way. Here's a sea hibiscus (picture below). Third 'discovery'.
Discovery Note:
1. This fast growing tree commonly grows along the seashore and back mangroves.
2. The yellow flowers open in the morning (after sunrise, about 9 am) and turn orangey brown before falling on the same evening or the following day.

Since it was an adventure trail we were going on, the walk naturally would be a bit more 'challenging'.

We had to navigate our ways through rocky paths, looking twice on where we step to ensure that we don't kill any life and an objective of reaching the other part of our trail on time.
(2 pictures below to record the trail we were on...)

Soon we came to one of our stops. A cave (picture below)!!! Fourth 'discovery'!
Hey, how often do we get to see a cave in Singapore anyway. =p
Discovery Note:
Tool of construction: waves

Estimated Time of construction: Over hundreds of years

Method: Constant ‘attention’ from the waves on the cliffs everyday

Progression: Little nooks to Caves!

As we passed the numerous small tidal pools along the way, our hunter seekers pointed out this cowrie (picture below) in one of them. Fifth 'discovery' of the day.
Discovery Note:
1. They have shells but it is usually covered completely by their mantle.
2. This mantle prevents algae and encrusting animals from settling on their shell.
3. They feed on algae and seaweed.

Moving further down the trail, we soon came to another wonderful creation by the waves of the sea (picture below).

On the sides of another tidal pool, volcano barnacles were spotted. Here's one of them (picture below) and this is the sixth 'discovery'.
Discovery Note:
1. These animals actually start life as free swimming larvae.

2. When it finds a good spot on a rock to settle down permanently, it will glue its head down on the rock and produce a shell around itself.

3. Volcano barnacles are usually found where there is greater water movement.

Reaching the second part of our trail, we were treated to the sights of more corals. A leathery coral or sometimes we call this, 'Dead man's fingers' (picture below). Seventh 'discovery'!
Discovery Note:
1. Leathery soft corals are made up of a colony of animals.

2. These animals are called polyp. They look like a very tiny sea anemone with a long body topped with tentacles.

The picture below shows a close up shot of a polyp (picture below)
Not all polyps look like this, this is just one example of many.
By the way, their tentacles will only come out if under water.

Addition Note on picture above (from Ria):
1. Hard coral polyps have smooth unbranched tentacles usually 6 or multiples of 6, while soft corals have branched tentacles, usually 8 or multiples of 8.
2. So the picture above shows polyps from a hard coral.

Ninth 'discovery' was star barnacles (picture below) which were everywhere on the cliffs we walked past.
Discovery Note:
1. When not under water, a set of plates shuts the opening in the middle of the shell of the barnacle, forming an airtight seal.

2. When under water, the barnacles will open their plates and extend their feathery, segmented legs for feeding on plankton

And very soon, we came to the 'famous tourist spot' on Sentosa (picture below).
Approaching the last station of our trail, we were treated to a galore of finds by our hardworking hunter seekers.

Tenth 'discovery', a snapping shrimp (picture below).
Discovery Note:
1. One of their pincers is greatly enlarged. Sometimes, the enlarged pincer can be as long as its entire body.

2. The enlarged pincer has one movable ‘finger’ held apart with a catch. When the catch is released, an explosive sound occurs.

Eleventh 'discovery', a unknown nudibranch (picture below) to me. Could someone tell me the ID of this nudibranch? Thanks!
(Entry @ 8 June 2007: ID for this is phyllodesmium briareum nudibranch. Thanks to CH for providing the ID!)
Twelfth 'discovery', a pair of marginated glossodoris nudibranch (picture below).
Discoverers, can you recall what are some facts about nudibranches?
Test yourselves and read my other discovery entries for discovery notes on nudibranches to check your answers.

Thirteenth 'discovery' was a brittle star (picture below).
This brittle star is about 1cm in diameter!

Discovery Note:
1. Like sea stars, they have five arms, spine and tube feet.
2. The brittle star may purposely throw off an arm to distract predators. They can regenerate their arms, but slowly.

After viewing all the discoveries, our hunter seekers released them back to where they were found, back to the wild and their homes.

Finally after a two hour plus walk, we managed to complete the adventure trail in one piece and still full of energy. Prove? Look at our group shot together (picture below). We've done it!Lastly, it's thanks to everyone who joined us today, all Naked Hermit crabbies and of course the weather for making our walk a 'sweat' free event. =)


Siyang said...

haha...wat a nice group photo! And super cute nudibranchs!


Hi July,

the unknown nudibranch is phyllodesmium briareum.

Wow! I only get to see it during diving leh.

DreamerJuly said...

Yo CH~

Thanks for the ID.