Pulau Sekudu is a tiny but rich island that lies just across from Chek Jawa, with a narrow but deep channel in between.
We arrive under a beautiful full moon and saw a stunning array of marine life! All kinds of sea stars and echinoderms, corals, sponges, strange sea anemones and more! Pulau Sekudu is indeed a precious part of our northern shores.
Today, the tide is very low. It is a minus zero tide! So finally, I get a chance to check out the reef edge on this tiny island. I'm glad to see that there are still a wide variety of
sponges growing on the rubble. Although the sponges are not as thickly encrusting as I remember them from the past.
It's the first time I've seen this strange large sponge. I have no idea what it is.
How nice to see these weird blue blobs again. We had seen them at Pulau Ubin in
2010. Today, I managed to get a shot of some that were still submerged. They sure do look like some kind of ascidian.
How nice to see several different kinds of sea fans today! There were many bright orange
Candelabra sea fans, a few red
Skinny sea fans, and a few long white
sea whips.
Sea fans are a great home for all kinds of animals. Today I saw several Winged oysters very firmly attached to the seafans. The seafan 'branches' are thickly twined with countless
tiny colourful brittle stars (
Ophiothela danae)! I only saw the little
red ovulid snail on a red sea fan when I processed the photos at home!
Another strange thing I noticed where these tight bands of green seaweed around some (not all) of the Candelabra sea fans. The bands were so tight that they actually constricted the growth of the sea fan. Hmm, I wonder what is going on?
Sam noticed tiny ovulid snails living in a soft coral too! These
False coweries live on
flowery soft corals (Family Neptheidae). They actually eat the soft coral. Their shells are plain or have some boring markings.
When their body mantle covers their shells, the snails blend perfectly into their soft coral home!
Later on, we learnt that Mei Lin and the rest also found ovulids in another kind of soft coral. We're not sure if these are the same kind of snails.
There are even living hard corals here! I saw only two, and they look like the same hard corals that I had seen since I have been visiting Pulau Sekudu for the last ten years or so. This one looks like some kind of
Boulder sandpaper coral (
Psammocora sp.).
While this one looks like some kind of
Favid coral with tiny rings (
Cyphastrea sp.).
Another strange encounter was with these super huge zoanthids! See my size 7 (20cm long) bootie next to the clump. I have no idea if these are something different from the usual zoanthids that we see. They are much larger than the
Broad zoanthids (
Palythoa mutuki).
As usual, the most amazing find is seen just before we have to leave as the tide rushes in. It's some kind of strange anemone. It looks like a green version of the
Haeckel's anemone (
Actinostephanus haeckeli). I saw something like this at Chek Jawa in
2009. A little earlier, Sam found a black lump that did look like a retracted Haeckel's anemone. We'll have to deal with this scary look anemone another time.
There were lots of
Swimming anemones (
Boloceroides mcmurrichi) on the shore today. Both big ones as well as lots and lots of teeny tiny ones all over the seagrass meadows. The rubbly area was carpeted with
Posy anemones.There were also lots of
flowery sea pens (Family Veretillidae),
Common sea pens (
Pteroides sp.) and some
Common peacock anemones (Order Ceriantharia). And I saw some very small
ball flowery soft corals (Family Nephtheidae).
There are a lot of food fishes on Pulau Sekudu. I saw a small
Chocolate hind (
Cephalopolis boenak), a kind of grouper. Also several
rabbitfishes (
Siganus canaliculatus),
Hoplodoris nodulosa and several
Spangled emperors (
Lethrinus nebulosus). There were of course also lots of other fishes like
gobies (Family Gobiidae), but there was just too many other things to pay attention to.
Pulau Sekudu is nudiland! A bewildering variety of nudibranchs and slugs can be found here. I only found the obvious and easy ones like the
Blue dragon (
Pteraeolidia ianthinia),
Hoplodoris nodulosa,
Discodoris lilacina,
Thordisa villosa. The rest of the team saw an amazing number of species. Chay Hoon will as usual, manage the nudi situation. James has already posted lovely
photos of a bunch of slugs!
These may look like slugs but they are actually cowrie snails! These are
Miliaris cowrie (
Cypraea miliaris), I think. The two of them don't look exactly the same in both shell and body pattern. Hmm...
There are also many
Onyx cowries (
Cypraea onyx). This one was suspiciously next to a rather 'clean' sponge. Was it eating the sponge? Among the other molluscs I saw were plenty of
Fan shell clams (Family Pinnidae) everywhere.
Our northern shores are a haven for echinoderms! This includes sea stars. Today I saw lots and lots of
Biscuit star (
Goniodiscaster scaber), several young
Cake sea stars (
Anthenea aspera) including a bright orange one. Sam found a
Spiny sea star (
Gymnanthenea laevis) but I forgot to take a photo of it. In the dark, there were some
Painted sand stars (
Astropecten sp.) and
Plain sand star (
Astropecten sp.). Marcus found a
Crown sea star (
Asterina coronata) and also a
Knobbly sea star (
Protoreaster nodusus) though.
Sea urchins are echinoderms too! There were lots of large
White sea urchins (
Salmacis sp.), including some that had bright pink spines. Are they also
Salmacis species? I saw some
Black sea urchins (
Temnopleurus sp.), pink
Thorny sea urchin (
Prionocidaris sp.) and two huge
Long spined black sea urchins (
Diadema sp.) which are more commonly seen on our Southern reefs.
Mei Lin found tiny little heart urchins! These might be
Mareta planulata, our first sighting of them in the North.
Marcus found a lovely
Blue feather star. We often see this also on Pulau Ubin as well as even Changi.
There are lush seagrass meadows on Pulau Sekudu. I saw a few patches of nice long
Tape seagrass (
Enhalus acoroides). But the most abundant species are
Spoon seagrasses (
Halophila ovalis) . There are also lots of
Fern seagrass (
Halophila spinulosa). Today I didn't manage to see the
Serrated ribbon seagrass (
Cymodocea serrulata) that I saw on my last trip.
Alas, I saw a fish trap right at the edge of the reef. It was a bit tricky to get to in the dark, so I had to leave it there. We also saw a massive hole in the reef edge (about 5m wide and very deep). It was probably made by a boat striking Pulau Sekudu.
We started well before sunrise, under a wonderful full moon with a more or less clear sky!
We enjoyed a beautiful sunrise, with the Chek Jawa beacon on the horizon. But as usual, sunrise means the tide is turning and it's almost time to go home.
There are lots and lots of
Haddon's carpet anemones (
Stichodactyla haddoni) on Pulau Sekudu. The density seems higher than currently at Chek Jawa. Many carpet anemones were killed during the
mass deaths of 2007, and from what I see on Chek Jawa, the numbers do not seem to have returned there since then.
Pulau Sekudu seems to be the last stronghold of the amazing marine life that I used to see on Chek Jawa in the past! Hopefully, should the situation at Chek Jawa return to the way it was before the 2007 mass deaths, the marine life from Pulau Sekudu will help to 're-seed' Chek Jawa. Pulau Sekudu is indeed an important part of the ecosystems not only at Chek Jawa, but also other northern shores like Changi.
We seldom visit this pretty island nowadays as it is off limits since 2007 and
requires special permission from NParks. We were visiting with NParks permission to do a quick survey. Our last survey was in
October 2011. Thanks to Alan at NParks for permission to visit and to Chay Hoon for organising the trip! And for the rest of the volunteers for helping to thoroughly survey this small but very rich island.
Posts by others on this trip
- Marcus on facebook with Knobbly sea star, octopus and slugs!
- James on facebook: a huge variety of slugs we saw today! Also on his blog.
- Rene on facebook with slugs and more!
- Chay Hoon on facebook with more slugs, stars and sunrise!
- Sam on facebook with moray eel, butterflyfish and glorious sunrise!
- Mei Lin with more nudis, crusties and other colourful marine life!
- Russel on facebook with MORE sightings of his first trip to Sekudu.
- Jerome on facebook with lots of stars.
