23 January 2011

Windy at Sisters Island

A small team is back on the shore on a very VERY windy day. While wind keeps the nasty sandflies away, it also ruffles the water making it almost impossible to see or shoot through the water.
Despite this frustration, all kinds of amazing creatures were sighted! Of course, I missed all the good sightings like the sea snake, 'Nemo's, transparent flatworm, special anemones which the rest of the team saw.

Nevertheless, I enjoyed taking a closer look at 'boring' areas which were protected from the incessant wind. It's much calmer, for example, in the forest of seaweeds that float in the lagoon. There is a bloom of Sargassum seaweeds (Sargassum sp.) on the reefs everywhere. This forest of brown blades shelter a galaxy of tiny animals.
Among the minature marvels are tiny hairy isopods (Order Isopoda), dove snails (Family Columbellidae) which seem to be grazing on the white stuff growing on the seaweed blades, and lots of tiny green shrimps with a bent back. Some of them were carrying eggs!
I almost missed the White-spotted rabbitfishes (Siganus canaliculatus) that were sheltering in this clump of seaweed. They are so well camouflaged. I first saw one fish, then two fish. When I got home I realised there were THREE fishes there. Can you see them?
Another critter discovered at home while looking more closely at the photographs. A very flat isopod-like creature that blends perfectly with the seaweed blades.
Some of the Sargassum had elongated portions on them. I'm not sure what they are, though I do know they are not fruits. Seaweeds don't produce flowers or fruits. They reproduce in a complicated manner involving weird 'spores' and stuff which makes them sound positively alien. The round bubbles seen on Sargassum are air-filled floats that help keep the seaweed close to surface of the water and sunlight.
Entwined among the Sargassum is a feathery forest of Hairy green seaweed (Bryopsis sp.). More tiny creatures can be seen here. I'm not sure what the hairy orange wormy creature is: scaleworm, bristleworm? There were of course many Bryopsis slugs (Placida dendritica), lots of tiny transparent shrimps, and countless beachfleas (Order Amphipoda).
This is not green seaweed but a large and lovely ruffled Ornate leaf slug (Elysia ornata).The rest saw marvellous slugs such as the Moon-headed slug (Euselenops luniceps).
This filefish (Family Monacanthidae) stayed very still. It is upside down in relation to this view so it looks quite unfish-like and is easy to miss.
How is coral bleaching at Sisters Island? Alas, it seems some of the large hard corals are still bleaching. I don't remember seeing this during our trip to Sisters Island last month. But perhaps I didn't come by this part of the shore at that trip.
Here's a closer look at a large hard coral. The lower portion seems still alive, but the upper portion is already dead with green algae growing on the dead parts.
This large Pore coral (Porites sp.) seems to have patches of dead parts which are being taken over by green algae.
I'm not sure what is happening to this hard coral. There is a patch that is clearly alive but much darker than the rest.
Here's a closer look at a healthy coral with coloured polyps. It's nice to see the hard corals at night as their polyps are usually extended at this time.
A nice brown Zebra coral (Oulastrea crispata) next to a patch of Feathery soft corals that seem to still be bleaching.
I only managed to see a few Circular mushroom corals (Family Fungiidae). They seemed unbleached, although this one has a bright pink patch which usually suggests stress or disease.
I saw one unbleached Sandpaper coral (Psammocora sp.), and one unbleached leathery soft coral (Family Alcyoniidae).
Favid corals (Family Faviidae) remain the most commonly seen coral on the shore. Most seemed unbleached. There were many small colonies all over the place.
I saw some patches of corallimorphs (Order Corallimorpharia) which were not bleaching. And also some healthy Frilly anemones (Phymanthus sp.). Kok Sheng saw some special sea anemones including the Pizza anemone (Cryptodendrum adhaesivum), but also one bleaching Bubble-tip anemone (Entacmea quadricolor). More about coral bleaching on Bleach Watch Singapore.
Sisters is usually a very fishy place. But it was hard to photograph them today with the ripply water. I saw one False scorpionfish (Centrogenys vaigiensis) and several other fishes whose identity I don't know.
It's less challenging to photograph slower moving animals like snails. I saw this snail which I don't know. It is probably some kind of Drill (Family Muricidae).
Also, a Wandering cowrie (Cypraea errones). I've started to take a closer look at 'common' cowries just to be sure they are not something else which might be less common. The Wandering cowerie has one or two brown spots at the front of the shell, and its 'teeth' are not coloured.
And this tiny whelk. I'm not sure if it'sthe Prickly whelk (Nassarius crenoliratus) or something else.
Other snaily finds include the Dolphin shell snail (Angaria delphinus), and lots of busy Dwarf turban snails (Turbo bruneus).
I almost missed this Reef octopus in the ripply water.
I saw quite a lot of brown Floral egg crabs (Atergatis floridus) and many swimming crabs (Family Portunidae) of all kinds.
I saw another Ashy pink sea cucumber (Holothuria fuscocinerea). It was hiding among the rocks and is quite sensitive to the flash, retracting quickly after the first photograph.
There were many brittlestars on the shore. But all I could see of them were their long spindly arms which retracted rapidly as soon as my torchlight fell on them.
As the tide turned, I had a closer look at the sandy shores. Here, there were spotty prawns which seem unlike the ones I usually see.
And several pretty little gobies (Family Gobiidae). I don't know what kind they are, but they are very well camouflaged against the sand and I only spot them when they move.
Another pretty goby.
This tiny Flower crab has caught some stripped titbit. Several little gobies tried to steal it away from the crab.
On the high shore, we saw lots of Land hermit crabs (Coenobita sp.). In a burrow well beyond the high water mark, in the middle of grass, I saw the legs of a crab. Could this be the rarer Smooth-eyed ghost crab (Ocypode cordimana)? There's so much more to discover about our shores!

I also removed an abandoned driftnet from Sisters Island today.

The rest of the team saw all kinds of marvellous creatures too! It's good that we had spread out to cover more ground and make separate sightings. Also makes it more fun to read one another's blogs!

Other posts about the trip


  1. Hi Ria,

    Yes, the Sargassum is "fruiting". The reprodcutive structures you described are called recpetacles, which hold the conceptacles, which contains antheridia (male) and oogonia (female). Transfer of he male gametes is by water.

    By the way, good capture of the rabbitfish - they are one of the main predators of Sargassum, although I'm not sure if they actually eat our sediment-covered ones!

    Cheers, Jeff

  2. Wow, thanks Jeff! Wah, reproduction in Sargassum is quite awesome! I didn't know rabbitfish ate sargassum! Will take a closer look at the sargassum community the next time I'm out there.



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