Sunday, May 31, 2009

Hunting Seeking at P.Semakau

We were back at Pulau Semakau on 30 May to hunt & seek. Our primary task this time round, was to look for species of algae, particularly the unidentified ones. Yet another challenging task (second to seagrass transect), we ended up collecting samples of almost every species of algae we saw since we were not certain of their identity. Our guiding principle for the day was 宁可杀错 不可放过. =)

I was so focused on identifying the seaweeds that I only remembered to take photos of 2 species. =P

Algae, or seaweeds, do not have a root system and also rarely have strong supporting stem-like structure. Unlike many plants, it has no veins, no flowers and typically has a similar colour throughout the entire plant.

Now, if you think that seaweeds/ algae are only green in colour, you will be surprised (like how I was ,prior to joining this project) to know that they are commonly clad in red or brown too!

This algae, which I'm not sure of the species, is likely to be from the genus of brown alga Sargassum. However, we observed that it does not have a living life jacket ie special gas-filled sacs, to help it float.



We also saw plenty of Napoleon's hat (Avrainvillea sp). This green algae is velvety and soft to the touch. Unusally flattened, it grows on soft sand/ mud, with its fan-shaped blade sticking out from the substrate.



We were lucky to come across this Sea Anemone, likely to be the Giant Carpet Anemone (Stichodactyla gigantea). While they may looked harmless, their showy tentacles contains nasty stinging cells. The stings however, do not hurt human beings, but may leave welts on sensitive skin.

Carpet anemones may come in array of colours due to the presence of symbiotic algae (called zooxanthallae). The algae photosynthesizes to produce food and shares it with the sea anemone, which in return provides the algae with shelter and minerals.

Knowing that the sea anemone also has a symbiotic relationship with the Ocellated Clownfish(Amphiprion ocellaris), we embarked on the mission of 'Finding Nemo' and were elated to spot 2 clownfishes darting about its home (try spotting one in video below!)

The anemonefish escapes the stings of the sea anemone by secreting a special mucus that covers its body. It enjoys protection from the sea anemone and may also feed on leftovers of prey captured by the host. In return, it protects its host from predatory fishes such as butterflyfish, removes parasites/ dead tissues and may even attract other fishes for the sea anemone's consumption.



video


A few steps away, the Synaptid Sea Cucumber was gingerly lashing its feeding tentacles in the water to pick out tiny organic particles/ detritus. One of the longest sea cucumber in existance, it can grow up to 3m long! I am not sure how long this chap is, as most of the body was hidden in the seaweed. I was wary of checking out its length (using my metal chopsticks) because of its thin body wall that causes it to be more dedicate than other sea cucumbers.
If you touch it gently, you will realised that the Synaptid sea cucumber sticks to your hands. This is due to their hooked spicules (instead of tube feet) which poke out of its soft body - works just like velcro!

Although a master of camouflage, this common Hairy crab or fondly known as teddy bear crab (Pilumnus vespertilio) could not escape our keen eyes! It is covered with long hairs which traps lots of mud and detritus. When we placed it in water, the hair instantly puffed up, breaking the outline of this creature - its way of fooling its predators.
When I showed this picture to my friends whom I met after the trip, it was not surprising that they very quickly associated this common hairy crab with 大閘蟹/ 上海毛蟹. They were visibly upset when I told them that this hairy crab is not edible, instead it is mildly poisonous due to its diet of zoantids!

While it was a short trip, it was still a fruitful one. At least now I know Ascidians (which we innocently collected, mistaking it for algae) are animals, filter feeders and commonly known as sea squirts (due to their ability to squirt jets of water). Their small short-lived tadpole-like larvae has notochord, thus they belong to the Phylum Chordata, just like you and I!

Tuesday, May 19, 2009

First! Mangrove survey @ Semakau

Finally after 4 mths of procrastination; numerous threats from LK (that she will kok my head), and an inspiration talk from GPA on review of Project Semakau, I finally decided to start my maiden post (on nature)!

Within the past 4 months, I've been to 2 transects, 2 mangrove surveys, 1 hunting seeking, 4 guiding sessions at sungei buloh... and no blogs! Enough said, I doubt I will backdate my entries (but I promise I will try), but lets start with 16 May 2009 - Mangrove survey #2.
As usual, we had our free mud spa. The only difference is that we also gave the mossies a good breakfast (see number of mossies on fellow GV's hat) as we tracked through the secondary forest.

First thing we came across was the sea derris (Derris trifoliata) which is one of the few climbers in the mangroves. This plant has compound leaves of 3,5 or 7 leaflets each. As the leaves & roots contains a chemical that is poisonous, they are sometimes crushed by fishermen who uses the sap as a fishing tool to stun or kill fishes.



There is high salt content in mangrove habitat with little oxygen in the mud as the soil is very compact. Mangrove plants needs to have special features in order to survive (try watering your plants with salt water, and you will know why)

One of such mangrove species with special features is the API API (avicennia species) . The leaves of Api-api bulu (Avicennia rumphiana) looks like soup spoons, and are furry/ hairy to help reduce water loss. They can also secrete excess salt through special cells on their leaves. Apart from providing support in the soil, their pencil-like roots can also breathe air to avoid suffocation in the oxygen-deprived mud.





In the same family, we also have Api-api Putih (Avicennia Alba) whose leaves are more pointed then Api-api Bulu (Avicennia Rumphiana). Like the name suggest (Alba means white in latin, and Putih means white in Malay), the underside of the leaves are white & waxy, with the upperside in shades of dark green. Like the Avicennia Rumphiana, the Alba also has pencil-roots to help it breathe. The fruits of Alba are also quite distinctive-they are conical with and look like commas (,) !


Another species of Avicennia, a rarer one, is Api-Api Jambu (Avicennia Marina). The leaves looked like that of A. Alba (pale on the underside too), but their fruits are broader, rounder, and bob/egg-liked. The cross-section of their steams are squarish, as compare to the other species which are rounded.
The Mata Ayam (Ardisia elliptica), a coastal plant, is named after its fruits because they look like and are about the size of the chicken's eyeball (ayam= chicken, mata = eyes) ! This plant can be recognised by its twigs which are swollen at the base. Unfortunately, the one I saw was not bearing any fruits. For better visuals, heres a picture of Mata Ayam taken in Semakau during my first mangrove survey in Feb 09.

We also saw the Sea Hibiscus (Talipariti tiliaceum), with its distinctive heart-shaped leaves. It is common in the back mangroves and the stringy bark is a source for making strings, ropes etc. The bright yellow flowers of the Sea Hibiscus opens in the morning and fades to dull orange-red
before falling the same evening.


The Sonneratia alba has very pretty flowers, which attracts bats and moths. The flowers are akin to the bats' pitstop/ starbucks where they replenish their energy by drinking the sweet nectar. This species is mainly found on the sea front. They do not have buttresses or prop roots but also has exposed roots that are cone-shaped (unlike the pencil-like ones of Avicennia).




Next up, we have the Bakau/ Rhizophora species. They are easily identified because of their prop roots which increased their stability in the mangrove mud. This species is also able to exclude salt by a filtering system in their roots (by taking in the water, excluding the salt largely - its amazing, if only I can enjoy coke and yet have a filter system to filter out the 8 spoonfuls of sugar). The timber of the Bakau is also deemed as an excellent source of wood.

We saw 2 species of Rhizophora - Rhizophora Apiculata (which has a red tip/ stipules, roots pointed downwards) and Rhisophora Stylosa (without the red stipules, roots spread out).

Rhizophora Apiculata



Rhizophora Stylosa

And, of course, theres the pretty Lumnitzera littorea. Found mostly at the middle to back mangrove where there is less salinity, this rare plant has bright red flowers, and would be easily identfied from far among the sea of greenery.



Enough of trees, my friend once commented after browsing through the photos I took during the first mangrove survey: "why you take so many RANDOM photos of trees?". Sigh, they are not random, because it took me great pains to identify them! I bet they will say the same of this post.

We also saw some crustaceans as we cross the river/ stream. Presenting candidate #1.... the soldier crab (Mictyris longicarpus?). Instead of flattened bodies, their bodies are round and they can walk forward unlike other crabs (i didnt notice this while observing the crab, I must be overly fascinated by this crab's attempts to tuck itself into a ball to fake death, and its numerous futile effort of escaping by digging holes to hide, only to be dug out by LK). The soldier crabs move in large groups of dozens or even thousands of individuals, but I only saw this lone ranger. Like sand bubbler crabs, the soldier crab eats the detritus on by scraping sand using its pincers to its mouth. The sand is then discarded, resulting in small, round balls of sand (the sand balls are however larger than those left behind by sand bubbler crabs).



Candidate #2 is the Porcelin Fiddler crab (Uca annulipes) are commonly found in sandier part of the mangroves, I think I saw at least 5 within a few steps. Those with one greatly enlarged claw (the other one, small) are the Males. The large claw is used to court females (attract attention, typical of males of many species. ha!) as well as to fend off love rivals. The smaller claw is used for feeding.


LK also showed us the Malaise trap, used as part of Nparks' insect survey. The insects flies into the large, tent-like structure and gets trapped. As they try to escape by flying higher and higher up the tent wall, they end up flying into THE container with the killing agent (alcohol, I reckon? smells like it).



The highlight of the day has to be my sacrificial act of bashing through thick mangroves to collect a sample of a certain species (amidst the embarrassment, I also forgot what we were hoping to find , Xylocarpus moluccensis right? Though it was X. Granatum in reality?). ANYWAY, the ultimate classic was that after all that hard work, I cut 2 (not 1, but 2!) samples of... R. Apiculata! Sigh, its such a common species, theres no need to go through all that trouble just to collect a sample..... of R. Apiculata. =(

In any case, it was good fun. =)