Aeolid Nudibranch

Nudibranchs have got to be one of the prettiest and most colourful marine invertebrates. No dives or intertidal walks would be complete without seeing one. I have been very fortunate to see several different species throughout the years. Nudibranchs are classified into four suborders and my personal favourite are nudibranchs from the suborder Aeolidina.

Aeolids are typically longish in body shape and have a pair of cephala tentacles that’s distinct from rhinophores. But what makes them stand out are the rows of cerata on their back. I always thought it gives them a funky and rebellious demeanor.
The cerata are actually respiratory organs. In certain species, a cnidosac occurs at the tip of each ceras. These functions as storage for nematocysts capsules for defence and many aeolids obtain the stinging nematocysts from their food source, for example hydroids.

This aeolid nudibranch spotted at Beting Bronok is an absolute attraction. It most probably is from the family Facelinidae. For exact identification to species, its radula would have to be examined.

A team of University of Queensland researchers studying sea slug pheromones have named the chemicals attractin, enticin, temptin and seductin……..very apt names for an alluring group of animals.

Pictures taken at: Beting Bronok, October 2007.


References:

Behrens, D. W., 2005. Nudibranch Behavior. New World Publications, USA.

Graduate Contact 2007, No. 36. University of Queensland, Australia.

Ceriagrion cerinorubellum; Agriocnemis femina; Lynx Spider

The world of insects is filled with peril as many of them are ferocious predators and it is really a survival of the fittest. A survey at Lorong Halus gave me an exciting insight into their prey-predator relationship.

Agriocnemis femina is a small damselfly measuring up to only about 17mm in body length. This species undergoes colour changes with maturity and mature males have a whitish synthorax. This dainty damselfly is common around ponds and drains and they share the same habitat with another damselfly species, Ceriagrion cerinorubellum.

C. cerinorubellum is about a size bigger than A. femina. They are fierce predators and it was not long before we chanced upon a C. cerinorubellum attacking and consuming an A. femina. The prey’s head had been consumed but we could clearly see that it was an immature male A. femina from the orange tip at the abdomen. The C. cerinorubellum was so engrossed on lunch that it simply ignored me as I approached it really close to get a clear picture.

In nature, it is a case of eat or be eaten. This time the predator became the prey. A Lynx Spider (Oxyopes sp.) had captured a C. cerinorubellum. Lynx Spiders have keen eyesight and they hunt down their prey with very agile movements. This individual must have sprung an ambush on C. cerinorubellum which did not stand a chance once the spider sank in its fangs.

As we were leaving Lorong Halus, C. cerinorubellum reminded us that it is still an awesome predator among the small invertebrates. I managed to record a video of one consuming a fly-like insect. I would imagine the chase prior to capture must be quite a dogfight, a battle for air supremacy on a miniature scale.

These little insects might not have the iconic status of lions or tigers. But they are just are vicious and ruthless when it comes to feeding time. I think back to the movie ‘Honey, I Shrunk the Kids’. With these fearsome insects around, that would be a real nightmare comes true.

Pictures and video taken at: Lorong Halus, November 2007.

References:

Koh, K. H. J., 1989. A Guide to Common Singapore Spiders. Singapore Science Centre.

Orr, A. G., 2005. Dragonflies of Peninsular Malaysia and Singapore, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

Stichopus herrmanni vs Stichopus chloronotus

The identity of the sea cucumber (see post) spotted at Pulau Semakau in August has finally been confirmed as Stichopus herrmanni. Below is the reply from Dr. Claude Massin from the Royal Belgian Institute of Natural Sciences in Belgium.

“Dear Colleague,

At first glance your specimen could be confused with a Stichopus chloronotus. However, if S. chloronotus has large dorsal papillae with orange tips, these papillae are always well aligned on rows. On your specimen, all the dorsal papillae have the same size and are evenly dispersed. This colour pattern is more reminiscent of S. herrmanni. Moreover, you have a lot of rosettes in your preparations. In S. chloronotus the rosettes are said to be absent or very rare. If you check the size of the C-shaped rods, it is also easy to separate S. chloronotus from S. herrmanni.

S. chloronotus: in dorsal body wall, maximum 45 µm long; in ventral body wall maximum 70 µm long.
S. herrmanni: in the dorsal body wall, 35-100 µm long; in the ventral body wall maximum 150 µm long.

I think your specimen is a particularly dark morph of S. herrmanni.”

Stichopus herrmanni (dark form)

Stichopus chloronotus

Stichopus herrmanni (greyish-green form)

In all the previous reference books and papers, pictures of S. herrmanni are always greyish-green or brownish-green in colour. Looks like we have observed a rather rare dark morph of this species.

Several studies on their reproductive cycle have been conducted in various parts of the world. In Iran, S. herrmanni spawn during the peak of summer in July-August while in New Caledonia, they spawn during the months of January-February. In both cases, warmer seawater temperature is the trigger for reproduction. I wonder what is the situation in Singapore where there is no significant seasonal climate differences in tropical Southeast Asia.

I’ve had the opportunity to interact with several echinoderm experts around the world and have gained much knowledge. I certainly look forward to more advice from them.


Pictures taken at: Pulau Semakau, August 2007; S. chloronotus and S. herrmanni (greyish-green form) are from the book Taxonomie des holothuries des Comores.

References:

Massin, C., Y. Zulfigar, A. S. H. Tan & S. Z. Rizal Boss, 2002. ‘The genus Stichopus (Echinodermata: Holothuroidea) from the Johore Marine Park (Malaysia) with the description of two new species’, Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, Biologie, vol. 72, pp. 73-99.

Samyn, Y., D. VandenSpiegel & C. Massin, 2006. Taxonomie des holothuries des Comores, Abc Taxa (Volume 1), Belgium.

Tehranifard, A., S. Uryan, G. Vosoghi, S. M. Fatemy & A. Nikoyan, 2006. ‘Reproductive cycle of Stichopus herrmanni from Kish Island, Iran’, SPC Beche-de-mer Information Bulletin, vol. 24, pp. 22-27.

Sand Star

Sand Stars (Archaster typicus) is one of the more easily seen sea star on our shores. During low tide, they will emerge from the sandy sediments and they could also be located by the star-shaped impressions left on the sand. This is especially so on the sandy shores of Pulau Semakau. We spotted several mating pairs and the Temasek Poly students wondered how copulation takes place.

A. typicus belongs to the family Archasteridae. This is a small family with only one single genus, Archaster. Sand Star males are slightly smaller than females and a mating pair will always involve the male superposed on top of the larger female. However, fertilization occurs externally where both male and female synchronize the release of sperm and eggs. Thus copulation, which infers internal fertilization, is probably the wrong term to use. Pseudocopulation is the term widely used by scientists.

Sand Star is one of only two sea star species currently known to perform male-on-female superposition sexual behaviour. Most other species conduct aggregate spawning. It is not exactly clear why Sand Stars superpose during breeding. It could either be to increase the chances of fertilization when the eggs and sperm are dispersed into the water or it is a mate guarding behaviour.

Pictures taken at: Pulau Semakau, August 2007.

References:

Komatsu, M, 1983. ‘Development of the Sea-star, Archaster typicus, with a Note on Male-on-female Superposition’, Annotationes Zoologicae Japonenses, vol. 56 (3), pp. 187-195.

Lane, D. J. W. & D. VandenSpiegel, 2003. A Guide to Sea Stars and other Echinoderms of Singapore. Singapore Science Centre, Singapore.

Gold-spotted Mudskipper

It has been a while since I stepped into a mangrove and I’m beginning to miss the mudskippers, or as Rachel would affectionately call them the ‘doink-doink-doinks’ because of their locomotion on land. Their movement of pectoral fins pulling and dragging the body forward always leaves a distinctive trail on the mudflat.

Gold-spotted Mudskippers (Periophthalmus chrysospilos) have pretty orange spots along their body and some of them can appear yellowish in colour. They are rather common and easy to identify from afar. One of the diagnostic features separating this species from other mudskippers is their fully fused pelvic fins that form a round disc.

P. chrysospilos has a small gill area compared to other mudskippers. They are thus less efficient in aquatic respiration and so more adapted to land than water. Their breeding period is thought to be between May and July when they’ll become less seen as they spend more time in their burrows. Males will attract females to their burrows with vigorous courtship displays. Once paired, the male will defend his burrow and surrounding territory against all comers including mangrove crabs!


Pictures taken at: A southern offshore island, December 2006; A northern offshore island, May 2006 and western part of Singapore, January 2007.


References:

Ip, Y. K., S. F. Chew, L. L. Lim & W. P. Low, 1990. ‘The Mudskipper’, in Essays In Zoology. Papers Commemorating the 40th Anniversary of the Department of Zoology, National University of Singapore, eds, L. M. Chou & P. K. L. Ng, Department of Zoology, National University of Singapore.

Larson, H. K. & K. K. P. Lim, 2005. A Guide to Gobies of Singapore, Singapore Science Centre, Singapore.

Stichopus cf. herrmanni

Another sea cucumber!! This time its from the family Stichopodidae.

I chanced upon it during a recent seagrass monitoring at Pulau Semakau. It has a thick body wall, a lumpy body surface and is covered with orange papillae which contrast brightly against the black body surface.

Following the advice from Dr. David Lane, I proceeded to obtain some tissue samples from the dorsal tegument before returning the creature back to the sea.

After several failed attempts at ossicles preparation from a different species, I decided to try again. And voilà! The beautiful ossicles appeared as I adjusted the microscope’s focus. Intricate tables, C-shaped, S-shaped and branched rods of various patterns came into view. It’s a real wonder that these microscopic skeletons have, over evolutionary time, been reduced to these beautifully elaborate 3-D structures.

Based on the references, the ossicle shapes and general morphology would identify it as a Stichopus sp. and it most resembles Stichopus herrmanni. However none of the references noted S. herrmanni appearing in black. Looks like I’ll have to search deeper into sea cucumber taxonomy.

Sea cucumber ossicles, the real beauty is within.

Pictures taken at: Pulau Semakau, August 2007.


References:

Clark, A. M. & F. W. E. Rowe, 1971. Monograph of the Shallow-Water Indo-West Pacific Echinoderms, British Museum (Natural History), London.

Colin, P. L. & C. Arneson, 1995. Tropical Pacific Invertebrates. A Field Guide to the Marine Invertebrates Occurring on Tropical Pacific Coral Reefs, Seagrass Beds and Mangroves, Coral Reef Press, U.S.A.

Lane, D. J. W. & D. Vandenspiegel, 2003. A Guide to Sea Stars and other Echinoderms of Singapore, Singapore Science Centre, Singapore.

Ictinogomphus decoratus

Most of the commonly seen dragonfly species belong to the family Libellulidae. Some of them have adapted to urbanisation and are thriving very well in the ponds and canals within our landscaped parks and gardens. Dragonflies from the family Gomphidae are less common. They are more sensitive to environmental degradation and thus in Singapore; they are more easily encountered in natural streams and water bodies.

Gomphids' pair of eyes is well separated and this is one of the features differentiating them from other dragonfly families. There are only about eight recorded gomphid species in Singapore. Yangchen spotted this striking Ictinogomphus decoratus during one of our surveys. Ictinogomphus species are large and they like to breed largely in standing water. I. decoratus in particular inhabits ponds and dams which makes them the most common among Singapore’s gomphid dragonflies.

This year we celebrate National Day at Marina Bay. Not many of the spectators would know that the few sedge ponds existing in the nearby Marina South and Marina East would soon be cleared for development. And so we will lose another location which supports good dragonfly diversity.

Pictures taken at: Western part of Singapore, August 2007.


References:

Orr, A. G., 2003. A Guide to the Dragonflies of Borneo. Their Identification and Biology, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

Orr, A. G., 2005. Dragonflies of Peninsular Malaysia and Singapore, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

Cake Star

A bright red Cake Star (Anthenea aspera) beckoned at Merawang Beacon!!

I was surprised to see this asteroid fully exposed during low tide. Its intense redness is a standout and it is large with an arm radius of about 11cm.

Anthenea aspera is rare within the Indo-Pacific region. Of the 31 asteroid species currently known from Singapore waters, A. aspera is among the largest. Their colour and patterns are variable ranging from dark green to dark pink. In Singapore, this species is first found from Changi in 1992 and has since been spotted at Chek Jawa and Pulau Semakau. Looks like they could also be found from our western shore.

The large bivalved pedicellariae on the oral surface is a typical feature of A. aspera. They are defensive structures that can be used to snip off any settling larvae and thus protect the Cake Star from encrusting organisms.

This Cake Star from Merawang Beacon is a real beauty!

Pictures taken at: Merawang Beacon, March 2007.


References:

Lane, D. J. W. & D. VandenSpiegel, 2003. A Guide to Sea Stars and other Echinoderms of Singapore. Singapore Science Centre, Singapore.

VandenSpiegel, D., D. J. W. Lane, S. Stampanato & M. Jangoux, 1998. ‘The asteroid fauna (Echinodermata) of Singapore, with a distribution table and illustrated identification to the species’, The Raffles Bulletin of Zoology, vol. 46 (2), pp. 431-470.

Pond Wolf Spider

While in the midst of spot lightning for the Barn Owl, I can’t helped but noticed the many Wolf Spiders’ eye shine on the grassy field. They seemed to be calling out for my attention.

Zeroing on an individual, I was pleasantly surprised to see a female spider carrying her spiderlings on her back. There are so many spiderlings that I could hardly see the mother at all. A study has concluded that mothers with spiderlings are more mobile with greater directional movement compared to other females. This higher mobility together with the gradual dismounting of spiderlings will aid in spreading the young throughout their habitat and thus avoid kin competition.

We noticed a male nearby following the mother. Yixiong tried to catch it and was promptly bitten. Ha-ha…. the spider lived up to his name.

Pond Wolf Spiders (Pardosa pseudoannulata) are fast running predators and can be found on the ground near water bodies. These spiders from the family Lycosidae has their eight eyes arranged in three rows of 4, 2, 2.



Pictures taken at: Pierce Road, May 2007.


References:

Bonte, D., S. Van Belle & J-P. Maelfait, 2006. ‘Maternal care and reproductive state-dependent mobility determine natal dispersal in a wolf spider’, Animal Behaviour, doi:10.1016/j.anbehav.2006.06.021

Koh, K. H. J., 1989. A Guide to Common Singapore Spiders. Singapore Science Centre.

Murphy, F. & J. Murphy, 2000. An Introduction to the Spiders of South East Asia, Malaysian Nature Society. United Selangor Press Sdn. Bhd, Kuala Lumpur.

Orange-bellied Flowerpecker

Sometimes nature will present its intimate moment at the most unexpected time. You just have to be lucky and ever ready to capture it.

We were hiking along Macritchie Reservoir when a pair of Orange-bellied Flowerpecker (Dicaeum trigonostigma) made an unannounced appearance. They fleeted among the Singapore Rhododendron (Melastoma malabathricum) bushes feeding on its fruits. The birds were only about two metres away and were uninhabited by our presence. As I took the pictures, Weiling’s nature guiding instinct kicked in and she promptly pointed the birds to a couple of passing tourist hikers. I hope the birds made the tourist’s day.



Male Orange-bellied Flowerpeckers have a beautiful orange breast and back with yellowish vent and coverts while the females are duller. They are our common resident. They can be seen flying energetically among the tree tops feeding on nectar, small fruits and insects.

The birds we saw sure looked like a loving couple.










Pictures taken at: Macritchie Reservoir, May 2007.


References:

Robson, C., 2000. A Field Guide to the Birds of South-east Asia, New Holland Publishers (UK) Ltd, London.

Polyplectana kefersteinii

I am now very intrigue by sea cucumbers. Everything about them fascinates me. Their docile nature belies a nasty defence mechanism; the myriad colours and sizes sea cucumbers can occur; they are not very well studied with many undescribe species and their overall squeamishness which, strangely, I find really appealing. And of course some of them really look like big poo.

There are about 1400 known species worldwide. They are classified into six orders and in total 25 families. I’ve so far seen representatives from five families on our intertidal shores. The latest is this one representing the synaptids.

A typical synaptid from the Order Apodida has no tube feet, has a very thin and sticky body wall and has no respiratory trees. Apodids’ oral tentacles can be simple or digitate or, like this individual has so beautifully demonstrated, feather-like.

This species is most probably a Polyplectana kefersteinii. But of course we would have to examine its microscopic ossicles to be 100% certain of the identification.

Picture and video taken at: A southern offshore island, March 2007 and Pulau Semakau, May 2007.


References:

Kerr, A. M., Holothuroidea. Sea cucumbers.
http://www.tolweb.org/Holothuroidea

Lane, D. J. W. & D. Vandenspiegel, 2003. A Guide to Sea Stars and other Echinoderms of Singapore, Singapore Science Centre, Singapore.

Ceriagrion cerinorubellum

Sex. What is your favourite position? For Odonates, it is the Wheel.

I spied this pair of Ceriagrion cerinorubellum damselfly in the heat of passion during my fieldwork. The female below had curled her abdomen towards the male’s genitalia to receive the sperm. And with that, the couple formed a beautiful heart shape wheel position. But all is not lovey dovey because the pair was engaged in a reproduction battle of wits.

The pair was locked in this position for almost 10 minutes. This long copulation period allows the male damselfly to remove rival sperm from the bursa copulatrix, a copulatory structure in the female. However in a classic case of cryptic female choice, the female retains control over reproduction as she can control the sperm reserves in her spermatheca. Knowing this, the male will prolong copulation to elicit the female to eject rival sperm and tempt her to use his sperm for fertilisation.

Thank goodness human reproduction is not this complicated.

C. cerinorubellum is a very common and colourful damselfly. They occur frequently in suburban gardens, drains and ponds. They are also vicious predators capable of tackling other damselfly species twice their size.

Colourful, ferocious and sexually competitive. Quite a character for a tiny insect!



Pictures taken at: A northern offshore island, March 2007 and western part of Singapore, February 2007.


References:

A. G. Orr., 2003. A Guide to the Dragonflies of Borneo. Their Identification and Biology, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

A. G. Orr, 2005. Dragonflies of Peninsular Malaysia and Singapore, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

Uhia, E & A. C. Rivera, 2005. ‘Male damselflies detect female mating status: importance for postcopulatory sexual selection’, Animal Behaviour, vol. 69 (4), pp. 797-804.

Polychaete (Family: Polynoidae)

Prof. Peter Ng gave a good speech at an Earth Day event last weekend. He touched on nature conservation in Singapore. Two main points stuck in my mind: 1) There is much more to discover from Singapore’s natural habitats. 2) We have to conserve and protect because our natural heritage belongs to us and nobody else and is ours to keep.

His speech strengthened my conviction to partake in local nature-related work. We must fight for nature conservation because if we don’t, we’ll not only lose our heritage but also things that maybe new to science.

Small invertebrates are a case in point. Many of them have been largely ignored by science. Some of them are difficult to study, some are hard to find and most are largely disregarded because they lack the ‘cute’ factor. But in actual fact, many invertebrates are fascinating and cute.

When I spotted this little critter, I thought it is some kind of sea slug. On closer examination, it turns out to be a polychaete from the family Polynoidae. It hardly looks like a worm and even has a bug-like motion.

There are 64 polychaete species in Singapore waters with only two species from the Polynoidae family. This is based on the last major polychaete study by Prof. Chou in 1993 where he reported 29 first time records for Singapore. 14 years has passed and Wilson has found several more new records.

Singapore certainly has many more minute fauna waiting to be revealed.



Picture and video taken at: A southern offshore island, March 2007.


References:

Tan, L. T. & L. M. Chou, 1993. ‘Checklist of polychaete species from Singapore waters (Annelida)’, The Raffles Bulletin of Zoology, vol. 41 (2), pp. 279-295.

Slender-lined Shrimp-goby

I’ve little knowledge on gobies before I started my current project. A year has passed. Through readings, consultations and trials and errors, I’ve gained much understanding of their ecology. Some of the most colourful gobies are the shrimp-gobies and their symbiotic relationship with the shrimps is most fascinating.

The Slender-lined Shrimp-goby (Cryptocentrus leptocephalus) is usually found on shallow reefs. They share a burrow with alpheid shrimps. The communication between goby and shrimp is ingenious. As the goby sits at the burrow entrance as a ‘guard’, the shrimp will touch the goby with its antennae. At the first sign of danger, the goby will flick its tail and both goby and shrimp will retreat into the burrow for safety. Researchers have shown that in the absence of shrimps, the gobies will not give a warning signal.

Ethology is an aspect in biological science that I find most interesting. Animals have many inventive ways to communicate both intraspecifically as well as interspecifically. Gaining insights into their behaviour and its meaning give me a sense of challenge. And the intimate knowledge gained reinforced my understanding of nature’s intricate connections at all levels. I hope to do some proper animal behaviour research in the future.

Picture taken at: Terumbu Pempang Laut, July 2006.

References:

Larson, H. K. & K. K. P. Lim, 2005. A Guide to Gobies of Singapore, Singapore Science Centre, Singapore.

Preston, J. L., 1978. ‘Communication systems and social interactions in a goby-shrimp symbiosis’, Animal Behaviour, vol. 26 (3), pp. 791-802.

File Shell

This File Shell (Lima lima) was uncovered when we were looking for worms under some rocks at Tanjung Rimau. Its appearance took us by surprise. We were both fascinated by the bright red tentacles and its shell valves clapping locomotion.

File Shells use an adductor muscle to clap their valves in order to achieve their free-swimming ability. The red tentacles are sticky and as a mean of defence, they’ll break off when attached to predators. This will thus allow the shells to make a quick getaway.

Our intertidal shores are full of captivating fauna from a myriad of forms and colours. The species diversity is mind-boggling.

Do go out there and explore all the nooks and crannies!!

Pictures taken at: Tanjung Rimau, February 2007.


References:

Tan, K. S. & L. M. Chou, 2000. A Guide to Common Seashells of Singapore, Singapore Science Centre, Singapore.

Tan, L. W. H. & K. L. Ng, 1988. A Guide to Seashore Life, Singapore Science Centre, Singapore.

Nannophya pygmaea

I remember a rather horrifying encounter with a dragonfly when I was very young.

I was a five year old kid visiting my grandma’s in a kampong in Malaysia. We were sitting at the dinning table when my uncle approached me with a gift. As he opened his fist, a huge back dragonfly suddenly flew into my face. It gave me a fright!! To make matters worse, he was holding a string tied to its abdomen and so the flying ‘monster’ was zipping all over me and the dining table. In an instant there was complete chaos as the dragonfly crashed into everyone and right into the dishes scattering all the food. It finally demised in a bowl of hot soup and my uncle got an earful from my relatives.

Now I’ve re-acquainted with the dragonflies and developed an immense liking for their beauty.

Dragonflies come in all colours imaginable. Their zipping and hovering flight are a delight to watch. They play an important role as indicators of environmental disturbances and many consider them a indicator species in streams and marshy habitats.

Male

Female

Nannophya pygmaea is one of the smallest dragonfly in the world. The adult male is bright red and will defend a small territory of only about one metre square. An interesting study on its territorial mating behaviour revealed that variations in male mating success is correlated more to the number of sunny days and less on male size.

Singapore’s plan to transform its concrete canals into landscaped channels has brought odonates into the forefront among local naturalists. There is now an initiative to study and update the status of Odonata in urbanised S’pore.

For me, this old song from 小虎队 best sums up the dragonflies.

飞呀飞呀
看那红色蜻蜓飞在蓝色天空
游戏在风中不断追逐它的梦
天空是永恒的家大地就是它的王国
飞翔是生活
我们的童年也像追逐成长吹来的风
轻轻地吹著梦想慢慢地升空
红色的蜻蜓是我小时候的小小英雄
多希望有一天能和它一起飞
当烦恼越来越多玻璃弹珠越来越少
我知道我已慢慢的长大了
红色的蜻蜓曾几何时
也在我岁月慢慢不见了
我们都已经长大好多梦正在飞
就像童年看到的红色的蜻蜓
我们都已经长大好多梦还要飞
就像现在心目中红色的蜻蜓

Pictures taken at: Western part of Singapore, February 2007.


References:

Orr, A. G., 2003. A Guide to the Dragonflies of Borneo. Their Identification and Biology, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

Orr, A. G., 2005. Dragonflies of Peninsular Malaysia and Singapore, Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

Tsubaki, A. & T. Ono, 1987. ‘Effects of age and body size on the male territorial system of the dragonfly, Nannophya pygmaea rambur (Odonata: Libellulidae)’, Animal Behaviour, vol. 35 (2), pp. 518-525.

Holothuria leucospilota

My initial impression of sea cucumbers was that they are really boring and rather disgusting creatures. They look like huge bloated worms and most of the time doing nothing but just….hanging around. But then I got my hands on some echinoderm books and I started to develop a liking for them, more so after encountering several sea cucumber species during the course of my work.

Sea cucumbers have evolved to lie on one side with the mouth and anus on opposite ends of the body. Their skeletons have been reduced to microscopic ossicles which are important in identifying species. Sea cucumbers feed by means of filtering suspended food particles or organic laden sediments using their feeding tentacles. They thus play an important role in helping to turn over reef sediments.

Holothuria leucospilota is one species I’ve encountered numerous times. They are usually exposed at low tide and are conspicuous in rock crevices. They kind of look like the excrement of a giant marine creature.

H. leucospilota is one of the species that ejects sticky white threads called Cuvierian tubules from the anus as a defence strategy. The repugnant tubules are believed to repel or entangle would be predators.

Sea cucumbers may be soft bodied and appear docile but they are not to be underestimated!

Pictures taken at: Terumbu Bukom, July 2006; St John’s Island, December 2006 and Lazarus Island, December 2006.


References:

Colin, P. L. & C. Arneson, 1995. Tropical Pacific Invertebrates. A Field Guide to the Marine Invertebrates Occurring on Tropical Pacific Coral Reefs, Seagrass Beds and Mangroves, Coral Reef Press, U.S.A.

Lane, D. J. W. & D. Vandenspiegel, 2003. A Guide to Sea Stars and other Echinoderms of Singapore, Singapore Science Centre, Singapore.

Colugo (Malayan Flying Lemur)

I got to know Norman Lim when I volunteered for his Pangolin survey. He is a nice guy, scholarly and has tremendous passion for animals especially those poorly studied nocturnal creatures. He also has a sharp eye and is always spotting well camouflaged animals others would miss. His Honours Colugo project and recently published book open a window into the Colugo's secretive life.






There are only two species of Flying Lemur in the world. The Colugo (Cynocephalus variegatus) and the Philippine Flying Lemur (Cynocephalus volans). They are of course not related to Lemurs at all but belong to the order Dermoptera. The taxonomy of Flying Lemur has been of much debate. Recently, genetic studies suggest they maybe closely related to humans!

And of course Colugos are one of the few mammals that glide. I was lucky to witness the feat a couple of times and it was quite a sight as the animal spread its patagium and glided effortlessly onto a tree trunk metres away. During the day they’ll usually rest in a tree hole or roost by perching against a tree trunk. It takes a keen observer to spot them.

These individuals were seen at Bukit Timah Nature Reserve and near the Tree Top Walk.

There is an estimated population of about 1500 in our forests. They do not do well in captivity but ironically there is a small population of free ranging Colugos in the Zoo. It seems they can survive well in landscaped and fragmented habitats. Nonetheless, it is crucial for the relevant authorities to conserve its shrinking habitats and protect this native enigmatic animal.

Pictures taken at: A northern offshore island, November 2006; Bukit Timah Nature Reserve, September 2006 and Tree Top Walk, November 2006.

References:

Agoramoorthy, G., C. M. Sha & M. J. Hsu, 2006. ‘Population, diet and conservation of Malayan flying Lemurs in altered and fragmented habitats in Singapore’, Biodiversity and Conservation, vol. 15 (7), pp. 2177-2185.

Francis, C. M., 2001. A Photographic Guide to Mammals of South-east Asia, New Holland Publishers Ltd, United Kingdom.

Lim, N., 2007. Colugo. The Flying Lemur of South-east Asia, Draco Publishing & Distribution Pte Ltd and National University of Singapore, Singapore.

Mud Lobster

We were just about to leave the survey site when Weiling and Shufen squealed in delight. They have sighted a Mud Lobster out of its mound!! We followed the bright red lobster as it scrambled over the mud mounds and debris.

We were urging it on and wondering where it was heading when it stopped and started digging into the mud. As it dug with its huge claws, we were expecting it to go right in. But surprisingly, it did a reverse maneuver and went in abdomen first thus completing a perfect camouflage!

It was indeed very fortunate for us to witness this common but rarely seen mangrove keystone species. The tall mud mounds they create are the result of processing huge amount of mud to obtain the organic material the lobsters feed on. The mounds will eventually become a key habitat for several mangrove animals like tree-climbing crabs, other invertebrates and even certain species of mangrove snakes.

I did a search on ScienceDirect and a surprising paper from 1942 turned up. It was written by researchers in Singapore recommending the use of lime and water to kill mud lobsters!! Their aim was to control the proliferation of mud lobster mounds thus eradicating breeding sites of malaria mosquitoes. Boy, am I glad our researchers have moved on from this mindset.

There are two species of Mud Lobster in Singapore. What we saw is most probably a Thalassina anomala. But the taxonomy of Thalassina genus is difficult and needs to be revised.

Pictures and video taken at: Mangrove in western Singapore, January 2007.

References:

Holthuis, L. B., Marine Lobsters of the World.
http://ip30.eti.uva.nl/BIS/lobsters.php?selected=beschrijving&menuentry=soorten&id=12

Ng, P. K. L. & N. Sivasothi, 1999. A Guide to the Mangroves of Singapore II, Singapore Science Centre, Singapore.

Scharff, J. W. & M. W. F. Tweedie, 1942. ‘Malaria and the Mud Lobster’, Transactions of the Royal Society of Tropical Medicine and Hygiene, vol. 36 (1), pp. 41-44.