Saturday, June 14, 2014

Sekudu survey with interesting sightings

The long awaited June Holidays is here where I will be able to do our morning intertidal surveys for 6 days back to back! The first trip is always the hardest as we have to wake up the earliest (at 2am) for our survey at Pulau Sekudu.

Despite visiting our shores for several times, I'm excited to still see creatures for the first time such as this beautiful nudibranch found by Ria. Chay Hoon has kindly identified this slug as Unidentia angelvaldesi.

The Unidentia nudibranch was originally found with the Fluffy hydroids. And I was surprised to see the hydroids move! This is because it came together with a crab decorated with the hydroids! Can you spot the crab in this photo?

Ria also found this Black-margined nudibranch (Glossodoris atromarginata) which is usually found more commonly in the southern waters of Singapore. 

Among the seaweed, Chay Hoon our slug expert found several Tiny black Gymnodoris nudibranchs (Gymnodoris sp.).

Chay Hoon also found this unidentified Gymnodoris nudibranch (Gymnodoris sp.) that we have also seen at Sekudu before in 2010.

Mei Lin had a special sighting of this unknown sea anemone that I have seen once before at Cyrene in 2011.

A closer look at this anemone reveals a pretty red "lip" on the mouth and also numerous white bumps on its dark orange body column. We hope this fellow will soon be identified soon. :)

Though it was really early in the morning, the shores are pretty alive with lots of action. I managed to catch a glimpse of the battle between a Stone crab (Myomenippe hardwicki) which found in the mouth of the Haddon's carpet anemone (Stichodactyla haddoni).

Here's a sequence of events from top left to bottom right where the crab won the battle by escaping from the carpet anemone! It came out together with some yellowish stain which I'm not sure whether it originated from the crab or the anemone.

There was even a tiny carpet anemone found attached on the blade of the spoon seagrass.

And on top of the baby carpet anemone, we came across this patch of seaweed with lots of juvenile marine creatures such as the White sea urchins (Salmacis sp.), Stone crabs, and an explosion of baby
Plain sand stars (Astropecten indicus) and Painted sand stars (Astropecten sp.).

Though the tide was not very low, we saw about 3-4 of these majestic Knobbly sea stars (Protoreaster nodosus).

I went back to the pool where I last saw several of these Common sea stars (Archaster typicus) and did not find as many of them as like the previous trip. Nevertheless, good to know that they are still around.

This pair of cute looking sea stars clinging tenaciously on the boulder is known as the Crown sea stars (Asterina coronata). They are sometimes also known as the Rock sea stars.

I went to check out the huge boulder where the two residents Long spined black sea urchins (Diadema sp.) are usually found and they are still there! The fishies are swimming around the sea urchin. I think it's some sort of protection for them though I'm not sure how they can avoid being hurt by the spines of the urchin. Haha!

As usual, there were plenty of the White sea urchins (Salmacis sp.) and many of them do "carry" shells and other bits and pieces with them as a form of camouflage.

Mei Lin found a Pink sand dollar (Peronella lesueuri) that has been regularly seen on Sekudu. This particular sand dollar looks like it has been chomped before by a predator. So far, we have only seen this sand dollar at Sekudu and Changi.

The Pink flowery soft corals (Dendronephthya sp.) can be found nearer to the coral rubble and they are home to commensals.

On this particular soft coral, there were several of these Tiny colourful brittle stars (Ophiothela danae).

A special echinoderm sighting would be this longish sea cucumber that we have probably not seen it before.

Here's a closer look at the mouth with the feeding tentacles sticking out. The body of this sea cucumber looks spiky.

Ria once again found this cowrie with torange mantle. This is probably the Graceful cowrie (Purpuradusta gracilis).

Ending off with fishy finds, I was relieved that no one stepped on any stingrays! The stingray in this photo is a Blue-spotted fantail ray (Taeniura lymma).

And Marcus found a special orangey fish that I forgot its identity. Will fill it in later. :)

That concludes our first survey of the week which ended before sunrise. It was quite zombifying for many of us and we hope that our body clock will adjust well for the subsequent upcoming trips.

Thank you Nparks for giving us permission to document Pulau Sekudu. As part of the Chek Jawa Wetlands, this island is out of bounds to the public.

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