02 October 2011

Living corals at Big Sisters Island, and two driftnets

The Sisters Islands have among our best reefs that ordinary people can visit. Here, I saw intriguing coral behaviour such as the long tentacles put out by this Carnation coral. The tentacles seem studded with  powerful stingers!
We also saw lots of fishes and sadly, also two driftnets.

Here's a pretty colony of Carnation coral (Pectinia sp.) with a fan worm. The coral didn't have tentacles extended. I wonder what makes a colony stick out its tentacles.
I also spotted the tentacles of the Ridged plate coral (Merulina sp.) for the first time!
I was delighted to see a large colony of Brain anchor coral (Euphyllia ancora). Unfortunately, the middle half seems dead. Though the edges of the colony still had living polyps.
A closer look and I realised the tiny tentacles with U-shaped tips emerge from a a broad fleshy base. I didn't know that! When I processed the photos, I realised there was an acoel flatworm on the coral too.
Other special corals I saw included a Bracket mushroom coral (Family Fungiidae) with tiny stubby tentacles. Also Lettuce coral (Pavona sp.) which has tiny corallites.
It was good to see several small colonies of Cauliflower coral and many colonies of Crinkled sandpaper coral (Psammocora sp.). These two species were badly hit during last year's coral bleaching. I saw only one Brain coral (Family Mussidae). There were still many Circular mushroom corals (Family Fungiidae) and many Anemone corals (Goniopora sp.) and one Galaxy coral (Galaxea sp.). As usual, there were also many large Pore corals (Porites sp.) and a great variety of Favid corals (Family Faviidae).
Among the hard corals was thing long squishy thing that retracted almost immediately after I took the photo. I'm not quite sure what it is. Perhaps it is some kind of sea cucumber?
Like many of our shores at this time of the year, there was a bloom of Sargassum seaweed (Sargassum sp.). Yesterday, Chay Hoon found the intriguing Sargassum slugs among the seaweed. She gave some tips and I tried hard to find some today. But the only special creatures I could find were many tiny green shrimps!
And the only slugs I saw in the Sargassum were several Ornate leaf slugs (Elysia ornata).
There are many other well camouflaged animal on the shore, like the Velcro crab (Camposcia retusa) which sticks all kinds of living sponges and other reef debris on the hooked hairs all over its body and legs.
But the Master of Disguise is Mr Stonefish! I almost stepped on him! The Hollow cheek stonefish (Synanceia horrida) is scarily quite commonly encountered on our shores!
The long branches of the Yellow prickly branching sponge (Pseudoceratina purpurea) often shelters fishes. This pair of Seagrass filefishes (Acreichthys tomentosus) stuck their noses against the sponge, perhaps hoping to appear to be the branches of the sponge.
But the best camouflaged fish on the sponge was a pair of Tiger-tail seahorses (Hippocampus comes) which Andy spotted. The rest of the team also spotted some seahorses elsewhere on the shore.
There were lots of other amazing fishes on this reef. My favourite is the Eightband butterflyfish (Chaetodon octofasciatus). Today I saw three of them!
There were many little colourful fishes which I have yet to figure out.
As usual, there are many Blue-spotted stingray (Taeniura lymma). I also saw many Spangled emperors (Lethrinus nebulosus), one Freckled goatfish (Upeneus tragula) and several Burrowing snake eels (Pisodonophis crancrivorus).
I was intrigued by this cowrie with a black mantle. When I gently looked at the shell, I realised it's the Four-spot cowrie (Cypraea quadrimaculata), something I don't often see!
As we were about to leave, we saw this little octopus on the sandy shore.
There was one large Haddon's carpet anemone (Stichodactyla haddoni) on the sandy shore with a pair of anemone shrimps (Periclimenes brevicarpalis)..
There's never enough time to look everywhere on the shore! So it's a good thing we had a large team today who surveyed different parts and found all kinds of interesting marinelife which we will soon read about in their blogs.

The team also worked hard at removing TWO driftnets that were laid across the beautiful reefs and trapped many fishes and crabs. They also damaged living corals.
We think the nets have been abandoned for some time because there were many dead fishes in the net. I didn't see the nets on our trip to this same shore four days ago. So the net was probably laid after that.
The dead fishes attract crabs that then get hopelessly entangled in the net.
There were some fishes that were still alive, probably recently entangled. We released them. Nets kill as long as they remain on the shore.
It was heartbreaking to see the damage caused by the nets. Thankfully, we had many hands to quickly document and remove the nets while releasing the animals that were still alive. More about the driftnet on the Project Driftnet blog.

Thanks also to Andy and Russel for bringing delicious curry puffs that we enjoyed before and after the trip!

Others who posted about this trip
Rene on facebook with feathery filefish, strange nudis, orange hermit crab and more!
Russel on facebook with lots of fishes, crabs and corals.

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