Hantu Blog's 3rd Anniversary Dive Part FIVE

The light of the apricot sun vanished over world's end, signalling the start of a dark adventure beneath the waves...

25 March 2007

Dive No. 4 - Denizens of the Dark Waters
Dive Site: Western Fringing Reef (Flabellina Garden)
Location: Pulau Hantu Besar
Visibilty: 3 m
Temperature: 29°C
Maximum Depth: 13.7 m
Actual Bottom Time: 61 mins
Time In: 1912 hrs

A truely unique experience and a rare chance to brave the dark side of Pulau Hantu. Due to the challenging and limited visibility, Hantu's waters are rarely dived at night. We were one of the fortunate few who had the opportunity to explore Hantu's nocturnal reef life. The fringing reef was bustling with activities after sunset and was like a circus of crabs and shrimps! Check out some of the specimens that you don't usually find diurnally.

Red Egg Crab (Atergatis integerrimus)

We came across 2 specimens of this species resting among the reef. They do not get spooked easily with the divers' careful approach. They are usually found in intertidal regions and down to about 50 metres, on rocky, coral, or mud shores. So we actually get plenty of them on Singapore's seashores.

The Red Egg Crab is a large oval shaped crab, with a wide and long, arc-shaped front edge to the carapace. It grows to a carapace width of about 12 cm.

The front of the carapace is extremely broad compared to the rear, which is quite indistinct. Two thirds of the way around its carapace edge, a blunt bump divides the front from the very short side and rear edges. The upper surface of the carapace is convex (curving outwards) and is quite smooth, without any major spines. It has large equal-sized chelae with brown or black fingers(pincers). Its legs often have distinct crests. The males of dark-fingered crabs have the usual complement of seven abdominal segments reduced to five by having segments three to five fused together. The Red Egg Crab is uniform light brown to reddish brown in colour, with white "lace-work" mottling on the carapace and brown spotted limbs. Underneath the carapace is cream in colour. The Red Egg Crab is poisonous and should not be consumed.

Oceanids Swimming Crab (Thalamita admete)

This is a fairly common swimming crab in Singapore waters. There are alot of similar species. Thalamita admete is distinct because the females have bright blue legs. The males are just drab orange-brown with spots. This Swimming Crab is classified under the genera of Thalamita because it has four teeth on each side of the frontal edge of its carapace whereas the Charybdis species have got five teeth. Swimming crabs are very good swimmers and can move very quickly on the reef. They are defensive and can inflict considerable painful wounds so are best left alone.

Cleaner Rock Shrimp (Urocaridella sp.)

This undescribed species is strictly related to Urocaridella antonbrunii but is recognised by its very transparent body and its much sparser white and red spotting. Its behaviour is similar to U. antonbrunii which I have described in an earlier post here.

This Urocardella sp. is pregnant with eggs under its belly. Take a closer look.

Red-Scissor Slender Shrimp (Kemponia tenuipes)

Sometimes also known as a Ghost Shrimp or Carid Shrimp. It probably derived its name from "tenuipes" which means slender/thin in Latin referring to the very long & thin first pair of arms. Incidentally, this & other long-armed shrimps which were formerly known from the subfamily of "Periclimenes" have been transferred to the genus Kemponia so the new name is Kemponia tenuipes. Kemponia is probably named for the british crustacean expert S.W. Kemp who did extensive research into the classification of their genus.

K. tenuipes is a very distinct species of shrimps with a pair of very long chelipeds tipped in orange-red colour. There are usually orange/red/yellow spots at its joints along the length of its chelipeds. They are small and are difficult to spot due to their almost transparent bodies. These long-armed shrimps are mostly found among coral rubble and in crevices. I have seen alot of these in the Similans but none of them seemed to exhibit any commensalistic behaviours(unlike shrimps of the genus Periclimenes) on other sea creatures such as anemones, seastars and urchins. This could probably be one of the reasons they were extracted out of the commensalistic family of Periclimenes as K. tenuipes is discovered to be a type of free-living shrimp.

There are 2 Emerpeor Shrimps and 1 Carid Shrimp within the interior of this Barrel sponge. Can you see them? Click the photograph above or see below for magnification.

Carid Shrimp (Kemponia cf. tenuipes)

This is apparently another species variation of K. tenuipes and appears undescribed(or I can't find reference to it). I have observed it on a few occasions(in Sg and Lang Tengah) within barrel sponges like the one above or in branching colonies of hard corals. As with nominal species of Carid shrimps, it has the characteristic long chelipeds but without bright colour markings. It is generally transparent with longitudinal red line along its body.

Emperor Shrimp (Periclimenes cf. imperator)

They usually show some degree of variation in their livery, possibly in relation to their choice of host. This small shrimp is less than 1 cm. They can be easily approached without difficulties.

Minstrel Shrimp (Metapenaeopsis hilarula)

This crustacea may locally be known as a prawn due to its larger size( carapace length of > 5 cm), but it is strictly a shrimp. As per defined by scientists, families of Decapods belonging to Infraorders; PENAEIDEA and CARIDEA are separately named shrimps and prawns due to their natural habitat. Shrimps are saltwater dwelling whereas prawns thrive in freshwater. Strictly, some saltwater genus should not be called prawns because of their larger dinner table size.

The Minstrel Shrimp is distributed around the Indo-pacific region from S.E Africa to Malaya. They are often found buried in muddy substrate and at night. They can be easily located with their glimming pair of eyes when you shine your torch over them.

Overall, this night dive was a very interesting one(as usual cos I love night dives!!). It was a dive filled with all the decapods crawling around busy with their work as they started their day nocturnally. The day with the Hantu Bloggers was really fruitful with all the startling finds I'd never expect to find in Singapore waters. A message out to all: Keep preserving Singapore's reef through conservation efforts(like what Hantu Bloggers are doing) and you'll see more of the living treasures of Singapore's own!

Sorry about the long delay of this last post due to very busy work schedules. Will try to find time to post up all the interesting encounters on my Lang Tengah and Similans trip. So wait on guys!

Hantu Blog's 3rd Anniversary Dive Part FOUR

25 March 2007

Dive No. 3 - Eyes of the Sunset Reef
Dive Site: Western Patch Reef (Cigar reef)
Location: Pulau Hantu Besar
Visibilty: 3 m
Temperature: 29°C
Maximum Depth: 13.7 m
Actual Bottom Time: 61 mins
Time In: 1712 hrs

We started on the Western Fringing reef and slowly moved north west to reach the Patch Reef. Along the way, Jimmy spotted an Octopus that swooped into a tiny crevice. Debby and I waited patiently for it to emerge but this intelligent creature just hid there motionless, only roving its eyes to check us out.

Can you tell the Octopus apart from the substrates of the reef? Look for its Eyes, it is looking directly at you!

There were lots of giant Mud Reef Gobies (Exyrias bellissimus) darting from hole to hole on the sandy reef. These fishes have large eyes above their head so they are sensitive to movements within their enhanced vision. As with other species of gobies, they are difficult to approach and will dash for the nearest hole when there's sudden advancement.

The Mud Reef Goby watched the approaching diver(me) cautiously while sifting through the muddy silt for food particles before darting off....

I came across an exposed tail of an unsuspecting fish. Curiosity got the better of me -I had to investigate. I tickled the tail of this fish to encourage it to emerge from the other side. It worked... A pair of sapphire eyes glittered and snared out at me! The fish was complete with 3 venomous spines and barbels. It grinned like an irritated cat before disappearing into a cramped crevice. That was unmistakably an Eel-tail Catfish. It was a pity that I missed capturing that crux moment when the mesmerising blue eyes interacted with me.

Tale of an Eel...... or not!

Despite their small size, Nudibranchs are among the showiest and the most interesting creatures of the reef. As I have previously introduced, Nudibranchs are sea slugs with no internal or external shell. They are so called Nudibranch because most species have a more or less evident tuft of gills on its dorsal mantle surface like the C. fidelis below. From Greek-latin to English context, Nudibranch is translated as "Naked-gills". You may be surprised to know that Nudibranchs actually have eyes! Their microscopic eyes sit deep inside the body on top of the brain. Although these slugs have eyes, these small black spheres cannot see images and colours of the reef. They are only able to distiguish light and dark which may warn the slug of predators by detecting shadows and are time keepers to help the slugs stay informed of day and night. What they lack in vision, they make up for it in ultra chemo-sensitivity. They have a pair of receptacles with tentacle-like retractable projections called the Rhinophores. Literally translated from 2 classic Greek words: "Rhino" = nose, and "Phore" = carrier. It is an organ of sensory "smell". The rhinophores can pick up scents of food, mates and even of predators.

Reliable Chromodoris (Chromodoris fidelis) "sensing" the water column for directions to its food sources and mates.

Flatworms have tentacles at the anterior end and often have brilliant colours they are occasionally mistaken for nudibranchs. But in contrast to nudibranchs, tentacles are mostly simple folds of the anterior margin. They can move along much faster than nudibranchs, are much thinner and tend to break up if handled. Furthermore, they don't have special respiratory organs (gills) as respiration is performed by diffusion through the worms entire surface. Polyclads exhibit a wide variety in colour pattern and texture. They have marginal ruffles tending to increase in number with size. Except opaque species which are black or mainly black, most species are transparent and their internal organs can be seen through the epidermis. Especially the ovaries can be bright red or deep purple and can influence the colour of the dorsal surface.
The anterior cerebrial ganglion knot and its large interneurons resemble the worm's "brain" analyzing nerve signals coming in from numerous photo- and chemosensitive cells which are concentrated mainly on head and pseudotentacles. Additionally, a high number of mechanoreceptors are dispersed throughout the epidermis. Photosensitive cells can be found in the cerebral eyespot where numerous eyes appear to form round clusters. Further eyes are located on the ventral and dorsal pseudotentacles. These eyes are not capable of forming images but are sensitive to changes in light direction and intensity. When flatworms sense bright light they usually retreat to a darker place.

Compared to vertebrates, the organization of polyclad eyes is quite simple. This type of eye, which lacks any lens, has been described as "pigment cup ocellus". Ocelli are part of the cerebral eyespot and are composed of several photosensitive cells and a concave cup. The walls of the cup contain pigments prohibiting light penetration from three sites. The light sensitive portions of the cells, microvilli, are arranged inside the opaque cup such a way that they can only be exposed by light from one single direction. Depending on the angle of incoming light, shadows fall onto the photosensitive structures. Since the cup can be actively rotated by muscles a quickly changing shadow pattern is generated. Corresponding excitatory nervous signals are sent to the cerebral ganglion where the information is analyzed and used for threedimensional orientation and appropriate behavioral reactions. -Text and Sketches of Flatworm adapted from: Anatomy of Polyclad Flatworms © Marine Flatworms of the World, Wolfgang Seifarth 1997-2002, All Rights Reserved!

A huge polyclad Flatworm (Pseudobiceros gratus)

A large Blue-spotted Fantail Stingray (Taeniura lymna) staring at me with its sinister looking eyes, warning me not to provoke it or else...... I thought of Steve Irwin for a moment and decided to ascend instead....

Hantu Blog's 3rd Anniversary Dive Part THREE

25 March 2007

Dive No. 2 - Operation Rescue
Dive Site: Southern Jetty
Location: Pulau Hantu Besar
Visibilty: 3 m
Temperature: 29°C
Maximum Depth: 13.7 m
Actual Bottom Time: 53 mins
Time In: 1335 hrs

We headed out in different groups and this dive turned out to be more than just fruitful. In fact, it was meaningful for most of us who rendered the release of trapped animals. There were bubus around the shallows laid down by fishermen. Most were discarded but some were still functional as traps for marine creatures. Those of us, who happened to come across enmeshed fishes, tried our best to extricate them unharmed. We yielded successful outcome.

I was surprised at first, when I noticed a Spanish Flag Snapper (Lutjanus carponotatus) laying perfectly motionless and head down in an unconventional position. Then I saw a hook in its jaw. I thought it was dead but as I approached, it put up a bit of futile struggle to break free from its painful entanglement. Before I set to release it, I checked the line... It was slacked. Debby came to my aid and together, we unhooked and disengaged the animal. It swam free... turning back again glancing at us as if with some sort of gratitude.

Afterwards onboard the boat, Geraldine told us they've encountered a strange shark trapped in a bubu but was also released unharmed. Chayhoon, Gina and some others also set free trapped fishes along their dive path. It was collectively a conservation effort by all who have a heart for the marine lives of Singapore.


The strange epaulette shark turned out to be a White-spotted Bamboo Shark (Chiloscyllium plagiosum) which is listed on IUCN Red List of Threatened species. See info here
The above shark photo is copyrighted and taken by Geraldine

Here are the other fantastic encounters:

The crawling jewels of the sea...

Black-margined Glossodoris (Glossodoris atromarginata)

Another purplish-orange colour variant of the Bullock's Hypselodoris (Hypselodoris bullockii).

My first sighting of The Emma's Hypselodoris (Hypselodoris emmae). Guess what? Take a closer look... It's laying its orange-red egg ribbon!!!

A Gold Speckled Flatworm (Thysanozoan nigropapillosum)

Then it was the little stuffs on the sea whips...

Allied Cowries

Left: An allied cowry extending its mantle to feed and digest part of the sea whip.

Right: A White-lined Whip Goby (Bryaninops amplus) living on its sea whip host.

Other interesting finds....
An almost perfectly camouflaged Crocodile Fish (Cymbacephalus beauforti) lying in the sandy bed. One way to differentiate Flatheads from Crocodilefish is to look into their eyes. Crocodilefish will interest most Macro aficionados. Close up shots of their jewel like eyes with their frilled eye lids or the details of the complex carpet-like decorations on their body are surefire winners.

A Carpet Eel-Blenny (Congrogadus subducens) is also called a Wolf Eel but it is neither an Eel nor a Blenny. In fact it's a Dottyback. It has a long body that's shaped like an eel's and is capable of changing its colour. The fish is sexually dimorphic - the female is pinkish brown while the male is green.

A school of Yellow-tail Barracudas swam pass as Debby and I prepared to ascend.

Hantu Blog's 3rd Anniversary Dive Part TWO

25 March 2007

Dive No. 1 - Sexy Sea Slugs
Dive Site: Northern Jetty
Location: Pulau Hantu Kechil
Visibilty: 2 m
Temperature: 29°C
Maximum Depth: 12.5 m
Actual Bottom Time: 66 mins
Time in: 1050 hrs

The waters in this narrow channel on the nothern side of P. Hantu was seemingly calm from the surface. The nearby reclaimation works on Pulau Bukom transmitted amplified sound waves underwater. Luckily, the head throbbing vibrations ceased a few minutes after we descended.
I buddied Debby and Jimmy and we worked west really slowly towards the Northern Jetty. As with any other muck habitats, the critter encounters were overwhelming. The following are some of the fauna I managed to photograph on just a single dive and amazingly, they were found in the highly discriminated waters of Pulau Hantu!

A Rosy Spindle Cowry (Phenacovolva rosea) that Jimmy pointed out to me on a gorgonian just under the jetty.

I flipped over a large piece of brown rotting Mangrove Apple leaf with my rod and guess what was clinging to it on the underside? A large and well camouflaged Dorippid Crab (Dorippe sp.)! The Brachyuran Crab pictured above belonged to the subfamily Dorippinae, family Dorippidae MacLeay, 1838. It is adapted to carry bivalve shells, leaves, jellyfishes, anemones, urchins or other objects on their backs by using the hooked dactyli of their last two pairs of pereiopods, which are dorsally located and mobile. The rare find of this Dorippid Crab in shallow waters of about 8m and its large carapace length of about 10 cm, narrowed its genera to the Dorippinae subfamily. This specific subfamily of the Brachyuran is only found in the Indo-pacific region and in shallow waters. They are larger in size as compared to their other Dorippid (Ethusinae) cousins which inhibits deep waters (>1000m). This subfamily consists of the following clades: Dorippe, Medorippe, Dorippoides, Neodorippe, Heikea, Paradorippe and Philippidorippe. Little information is known about the affinities and distinctions between the clades. Judging from the length of its eye peduncles, pereiopods and the shape of its carapace, I would deduce it to be from the Dorippe species and it sure looks uncannily alike to Dorippe quadridens. It has numerous bristle-like hairs over its surface to enable it to trap silt and sand particles for camouflage. The puzzling feature of this crab though is its missing chelipeds(the frontal pair of clawed limbs).

A vicious blood red Swimming Crab (Thalamita spinimana) holding out its pair of pincers, ready to strike!

After I lost Debby and Jimmy nearing the end of my dive, I was surprised to have had found at least 4 different individuals of the Orange-spotted Pipefish (Corythoichtys ocellatus) swim-wriggling around the sponge and algae covered pillars of the jetty.

A Bristle-tail Filefish (Acreichtys tomentosum) hovering near discarded metal pipes now overgrown with hydroids, algae and sponges. This species can sometimes be easily confused with its Strapweed cousin. Look for the characteristic elongated white patch which extends behind the gills.

Orange-edged Black Flatworm (Pseudobiceros hancockanus)

Unidentified Polyclad Flatworm... Need a little help on ID here..thanks

Undescribed Flatworm (Pseudoceros sp.)

Gold Speckled Flatworm (Thysanozoan nigropapillosum)

Left: A cuttle fish egg sac was laid down in the mud waiting to be hatched.

Right: The Pustulose Phyllidiella (Phyllidiella Pustulosa) is a Nudibranch commonly found in Singapore's waters.

Left: Managed to get the backside shot of the Reliable Chromodoris (Chromodoris fidelis) as it was wriggling into a muddy crevice.

Right: A Cake-icing Chromodoris (Chromodoris tumulifera) with its gills retracted into its branchial pockets.

The beautiful Bullock's Hypselodoris (Hypselodoris bullockii) seems to thrive well in muck environment like the waters of Singapore.

Intricately patterned Painted Hypselodoris (Hypselodoris infucata) raced across the silty bottom in search of food sources.

The Blue Dragon (Pteraeolidia ianthina) farm zooxanthellae in its cerata as a supplement to its basic diet of hydroids.

The Red-lined Flabellina (Flabellina rubrolineata) stores stinging nematocysts in the tips of its cerata as a defense mechanism. It obtains the stinging cells from its dietary hydroids and discharge them when harrassed.

Sex in the Sea

As functional simultaneous Hermaprodites, Ophisthobranchs maintain active male and female sex organs on every individual with reproductive pores generally postioned on the right side of their necks. The same species recognise each other by chemo-reception. Contact of body and rhinopores is made and there is a certain amount of courtship. They crawl around each other, lining up their genital openings. Copulation may continue for several hours or even days. Mating is performed by injecting sperm into one another simultaneously. Reciprocal receipt of sperm is through everted genital organs.

A little sketch in my logbook

Colour variations in Hypselodoris Bullockii is fairly common. They ranged from full purple forms, to pink, or even white specimens. Mating of the differnt colour forms are evidence of them being the same species as to what was previously debated in ID and anatomy.