Saturday, January 26, 2008

Changi on a Not-so-low-tide Evening

Tide wasn't really very low yesterday, but after my last encounter with the six-armed sea star and the heart urchin during a similar tide last month, decided to take my chances to go to Changi Beach again. Together with me were LK, ST, SJ and my friend ZY.

Well, unfortunately didn't managed to find the above two critters again this time round, but we still managed to find all sorts of interesting animals :)

A cute little leaf porter crab. Mind you, I didn't turn it over, but found it swimming in this position. Apparently, this helped it to hide from predators swimming below. They are usually found in this position at dusk or when they are attracted to lights.

There were so many sand stars every where that we had to be really careful not to step onto them.

Found this pretty sand star, probably a different species, emerging from the sand. Sand stars are predators of little shells, and I've seen them feeding on button shells before.

Like Chek Jawa, we saw lots of sea hare eggs as well.

And also, many hairy sea hares. About one year ago, we saw many of these hairy sea hares and their eggs as well. Could this mean that they have a consistent yearly breeding cycle?

I lost count of the pink thorny sea cucumbers I saw too. Many of them had their feeding tentacles out.

Found several salmacis sea urchins among the seaweeds.

Some of the bare batches of sand has many sand dollars hidden underneath too.

As it got darker, the brittle stars also started appearing.

Found a patch of seaweeds with lots of whelks. There were probably thousands of them. What attracted them here? Food? Or Sex? Or both? Really have no idea.

Found several of these sea anemones.

But the highlight of trip must be this seahorse! I was busy scanning around for sea stars and heart urchins and have not really been searching closely for other well-camouflaged animals. Fortunately the rest of the gang were looking at things more closely though :P

As it got darker, some of the tiny sea stars started appearing too. The one above could be a juvenile biscuit sea star.

Not sure about this one though. Saw a tiny green sea star as well during my last trip here with JL, so was really delighted to see one again this time.

Also found this sea urchin stuck to a durian shell. Spikes against spikes :)

Only saw a few sea pencils this time. I guess most of them were probably found on the lower shore which wasn't exposed during yesterday's not-so-low tide.

Found this bristle worm towards the end of our exploration. Apparently the rest already saw quite a few of them.

When we walked over to the artificial rocky shore, we saw several purple climber crabs.

There were a few onchs too. These are not sea slugs (which refers to opistobranchs such as nudibranchs, sap-sucking slugs and sea hares), but marine pulmonate slugs more closely related to land snails that breathe air using simple lungs. Some species hide in air pockets among rocks during high tide, while some other species are able to burrow into the sand during high tide, forming form S-shaped tubes with an air pocket from which they breathe during immersion. It is known that a few species can breathe through their skin underwater too.

We also found this moon crab stuck among some rocks, high and dry because of the low tide. We later put it back into the water.

Tide was already rising then and we had to leave. While we couldn't find the six-armed sea star and the heart urchin, it was still a great day with many interesting sightings.

And after washing up, it's off to my favourite coffeeshop for my favourite teppanyaki! :)

Wednesday, January 23, 2008

海星 。 管葵 。 仄爪哇


昨天跑了一趟仄爪哇(Chek Jawa),帮国胜做他的仄爪哇复原研究作业。 大约一年前, 我国与柔佛经历了百年罕见的暴雨。 柔佛河也因此泛滥成灾,造成大量的淡水涌入柔佛海峡。 处于河口的乌敏岛仄爪哇首当其冲,许多盐水生物因为无法在盐度严重下跌的环境中生存而惨遭灭绝。 而国胜的研究目的就是要观察与记录仄爪哇自然生态的复原情况。


这次的研究我被分配去观察管海葵(tube anemone, Order Ceriantharia)与飞白枫海星(common sea star, Archaster typicus)。 坦白说,那天我的身体状况并不是很理想。 不晓得是不是前一天吃错了什么东西,有种要吐也不是,要泻也不是的感觉。 幸好我这组不止我一个人,还有猪来和爱丽丝亚,要不然我可就有麻烦了。


仔细一看,才发现原来是毛海兔(hairy sea hare, Bursatella leachii)和它们的蛋! 海兔,海蛞蝓的一中,是软体动物家族中的一个特殊的成员,其壳退化成埋在外套膜中的一块小骨片。 从外表看,海兔的体形确实像一只兔子,而头部后边的一对较长的触角看起来有点象兔子的耳朵,所以它就获得了这个名称。

大约一年前,我们也看到很多海兔和海兔蛋。 似乎也只有产卵时期我们才会看到这么多的海兔。 平时它们是否也象以上这只往土里钻,所以我们才看不到吗?

走了一会儿,终于到达我们的观察地区。 下面便是一只管海葵。

管海葵,也叫管葵,严格来说并不是海葵,而是它的近亲。 我们的任务是记录观察范围内有多少管葵和它们的大小。

寻找管葵时发现这只对着我们张牙舞爪的花蟹。 有趣的是,当我们把它捉住从水中放到沙滩上后,失去浮力它似乎没有能力把巨大的钳子举起。 之前的横行霸道到了岸上,立刻变得英雄无用武之地。

我们也找到了这只漂亮的槭海星(sand star, Astropecten sp.)。 这可是只会钻进泥沙里猎食小贝壳类动物的肉食者。

刚做完第二个观察地区时,突然看到国家公园局的阿德尔在远处向我挥手,象是她找到了什么似的。 跑过去一看, 原来她找到了一只飞白枫海星! 寻找飞白枫海星正是我们的第二个任务,于是我们便张大眼睛找了一找,居然被我们找到了多九只!

自从一年前的水灾,原本相当普遍的飞白枫海星就消失了踪影,直到近几个月我们才开始找到几只。 这次能找到十只,还真是过去一年来的第一次! 真是太叫人兴奋了! 我们立刻把找到它们的位置记录下来,并且写下每只海星的大小。

很快地,我们完成了该做的记录,便继续到下一个管葵观察地区。 完成所有的观察后,发现管葵的数量比以前少了。 也不晓得是什么造成的。


星虫(peanut worm, Phylum Sipuncula) - 以前本地海边有很多。 农民还用它们来喂鸭呢! 廈门著名小吃土笋冻也是由一种星虫制成。

"蛋糕"海星(cake sea star, Anthenea aspera) - 成年的海星看起来象个星形蛋糕,因此得此名。

糙海参(sandfish sea cucumber, Holothuria scabra) - 海里的人参。 经过处理后可食用。在本地也叫秃参。


墨鱼蛋(cuttlefish eggs) - 不好意思,之前跟猪来说错了,这应该是墨鱼蛋,而不是章鱼蛋(octopus eggs)。 墨鱼蛋通常就象一串葡萄,而每个蛋的尾端象是被人捏了一把尖尖地。 章鱼蛋每个则象个小气球一般,尾端比较圆。 鱿鱼蛋(squid eggs)可就好认了多,通常都是长长好几条。在这里可以找到更多资料。

收拾好一切时,天色已晚,而圆月也已悬挂空中。 在迷人的月色下乘船渡海, 更是别有一翻韵味。

轻舟 。 遥月 。 乌敏岛
海星 。 管葵 。 仄爪哇




Note: Pai seh for those people who's English names kena translated to Chinese. Wahahaha...

Sunday, January 20, 2008

Chek Jawa Walk on 20 Jan 2008

Finally had my first guided walk of the year!

Guided at Chek Jawa for Nparks today, and with me were people from MND. We saw lots of interesting stuff, and guess I'll just highlight some of them today in this entry :)

And here's the gang at the top of the Jejawi Tower. Named after the nearby jejawi tree (also known as the Malayan banyan), the tower is about 20m tall, and gives a great view of the surrounding area.

After getting down from the tower, we entered the mangrove area, with swaying nipah palms (Nypa fruticans) growing on both sides of the boardwalk. We were quite lucky that one of the palm was flowering. Nipah palm, otherwise also called attap palm, is where you get your attap chee in your ice kacang from. During my kampong days, I used to live in an attap house which has a roof made from attap leaves :)

One sure sign that you are in a mangrove is when you see all these trees with exposed roots. The roots above belongs to the bakau trees (Rhizophora spp.). As the soil in a mangrove is usually very lacking in oxygen, mangrove trees adapt to this condition by having their roots exposed so as to take in oxygen from the air!

Near the end of the 500m-long mangrove boardwalk, we suddenly realised that we've entered crab territory. Hundreds of fiddler crabs (Uca spp.) were there waving their claws! And mind you, actually only the males have an enlarged claw. This claw is used to attract females, and also to intimidate other males.

Somehow we seem to have a lot of luck with elbow crabs (Family Parthenopidae) today. I saw at least five of them, despite that fact that they were usually so well camouflaged! Now, can you guess why they are called elbow crab? Just take a look at the pincers...

Several of my visitors were quite delighted to see the gong gongs (Laevistrombus canarium) in their natural habitat.

And of course, another familiar edible shell is the razor clam (Family Pharidae). Found it trying to burrow into the sand.

After the few days of heavy rainfall, I was quite relieved to see the resident carpet anemone (Stichodactyla haddoni)looking rather healthy. Hopefully we won't get another round of ultra heavy rainfall resulting in another mass death again...

Carpet anemones have sticky tentacles which trap animals that got too close to it. The tentacles has stinging cells that fire toxins into the animals to kill them. Acting like a conveyor belt system, the tentacles will also move the prey to the middle of the anemone, where the mouth is.

Found this sea cucumber again. Still, have no idea what species it is. Do you know that unlike us, sea cucumbers actually breathe through their backends?

As usual, there were lots of sand dollars (Arachnoides placenta) at the sand bar. They got their name because they look like coins.

And our first star of the day was this sand star (Astropecten sp.)! Quite surprised to see so many of them out so early, as most of the time they hide under the sand on a hot and bright day like this, and surface when it gets cooler and darker.

We were also quite fortunate that our hunter-seekers found us a seahorse (Hippocampus sp.) today!

Found a lot of these orange beehoon-like things among the seagrasses and seaweeds. These are sea hare eggs, and so I was expecting to see one of them along the way.

And indeed, we found a few hairy sea hares (Bursatella leachii)! Sea hares are basically snails with soft internal shells.

We also saw this sea star above, which for some time some of the guides had been wondering whether it's a juvenile cake sea star (Anthenea aspera) or a Gymnanthenea laevis, since it has the identifying features shared by both species. Personally I had thought it looked more like a cake sea star from its shape.

This time round, I finally remembered to take some close-ups of its upper surface to check for another identifying feature of a cake sea star that G. laevis lacks.

While it's not exactly super obvious, I was able to find some bivalved pedicellariae (those circled in red) on its top surface, and bigger versions were also present on its underside. Thus according to the "Guide to Sea Stars and Other Echinoderms of Singapore", this is most probably a juvenile cake sea star.

The hunter-seekers found two of these worms. Really have no idea what they are too. Hopefully some experts out there can answer me. They certainly didn't look like segmented worms to me, when another friend suggested that.

Yet another star find - a brittle star (Order Ophiuroidea)! And like its name, it is very brittle and its arms break off easily, so please handle it with care... Fortunately, they are able to regrow their broken arms though, but in the meantime, they will be at a disadvantage dealing with their everyday life with fewer arms.

And just before we got out of the intertidal area, we had a pleasant surprise of finding this cute little pink warty sea cucumber (Cercodemas anceps) hiding among some shells among the seaweeds!

After the walk at the jetty, we were given another treat from nature, with a few beams of sunlight peeping through the clouds, illuminating some boats in the distance.

What a way to end the day! Will be back at Chek Jawa to help KS on his project on Tuesday. Sure looking forward to see more great stuff!