22 December 2010

Changi is alive!

Lots and LOTS of little mudskippers were playing on the shore!
They didn't seem very shy and allowed me to get somewhat close.

Here's a video clip of them scampering about in the waves. The Gold-spotted mudskipper (Periopthalmus chrysospilos) is quite common on our Northern shores.

There is a nice natural rocky shore here. And it is particularly rich. Not only with all the animals that are found on the rock surface, but also those that hide under stones.
There were plenty of cowries under the stones! They were probably Ovum cowries (Cypraea ovum). Some of them were Mama cowries who refused to move and stayed put on the stone. This is because they are using their huge foot to protect their egg mass.
Here's a peek at the tiny yellow eggs under Mama's huge foot! This is why we must be gentle when looking under a stone. And to turn the stone back after having a look. Sadly, many stones were overturned on the shore and not turned back. I tried to turn back as many as I could.
Under the stones, I saw several black Hoof-shield limpets (Scutus sp.). and one of them had a huge barnacle growing on its shell.
The long purple sea cucumber is probably the Little african sea cucumber (Afrocucumis africana).
The rocks are gaily encrusted with sponges and other animals in startling colours! There were many large purple branching sponges (Callyspongia sp.), lots of melted chocolate sponges (Chondrilla australiensis), small patches of other colourful sponges. There were a few small colonies of the hardy Zebra coral (Oulastrea crispata). Some zoanthids still covered the higher shores
Encrusting ascidians coat the stones in maze-like patterns. These animals are actually grouped with us vertebrates because when they are very young, they have a primitive backbone! This disappears as the animal grows up and turns to a stationary lifestyle.
Under the stones, I saw two 'Rock' stars (Asterina coronata). Later on Kok Sheng found a large Biscuit sea star (Goniodiscaster scaber). We didn't see any Sand stars (Astropecten sp.), but probably because they only come out when it is dark. Rene did see two Thorny sea urchins (Prionocidaris sp.) and a Cake sea star (Anthenea aspera).
Among the rocks we saw this large cockle. It had feathery bits sticking out between the two valves. We often see this clam on rocky rubbly shores.
There is also a nice stretch of seagrass meadows here. The forest of lush Spoon seagrasses (Halophila ovalis) leaves provides shelter for a mind-boggling variety of tiny animals. Some grow on the leaf in lacy patches. There are also lots of tiny striped snails.
And this very tiny fish, which might be a very young Brown sweetlips (Plectorhinchus gibbosus)? It was even tinier than a seagrass blade! Seagrasses provide shelter for young fishes to grow up. Fishermen should thus protect the seagrass meadows so that they can enjoy their sport.
I was focusing on the well camouflaged rather fluffy elbow crab (Family Parthenopidae), that I almost missed the tiny shrimp (in lower right corner) on the leaf.
The tiny animals in the seagrasses make the small goby look enormous!
I also saw what looked like a shrimp goby with its partner shrimp. The fish was standing guard at the burrow entrance as the shrimp bulldozed up and down to maintain the burrow.
There were several small to medium-sized Haddon's carpet anemones (Stichodactyla haddoni) on the shore. I didn't see any with anemone shrimps in them. I saw one Swimming anemone (Boloceroides mcmurrichi) but no other kinds of anemones. Oh dear. We usually see many different kinds of anemones here. I also didn't come across any sea pens.
There were many peacock anemones (Order Ceriantharia) on the shore but most were retracted into their tubes. On Changi, the peacock anemones usually are infested with black Phoronid worms (Phylum Phoronida). The delicate fan of these worms sometimes hold a string of white balls like pearls, their eggs?
There were lots and lots of tiny to small Thorny sea cucumbers (Colochirus quadrangularis). I saw one Orange sea cucumber that was well 'wrapped' in dead seagrass leaves. I also saw one Purple sea cucumber out of water. When I put it back into the water, it showed its tiny tube feet. Kok Sheng later spotted a small Garlic bread sea cucumber (Holothuria scabra), and he also saw the Pink warty sea cucumber (Cercodemas anceps) and ball sea cucumber (Phyllophorus sp.).
A Spearer mantis shrimp (Harpiosquilla sp.) briefly scurried into view before disappearing into a burrow.
Most of the hermit crabs I looked at were Tidal hermit crabs (Diogenes sp.), with one enlarged pincer.
The shell of this hermit crab not only has white cap-shaped Slipper snails (Family Calyptraeidae) inside the shell opening, but also a tiny living scallop (Family Pectinidae) attached to it. Today, I didn't see any Fan clams (Family Pinnidae).
I've been motivated by Tan Siong Kiat's and Henrietta's checklist of Singapore molluscs (pdf) to look more closely at strange snails on our shores. And this is today's mystery snail. It was tiny (about 1cm) and found among the seagrasses.
The high shore is strewn with all kinds of mangrove seedlings!
I've arranged some of the seeds nicely here. The round one is the fruit of the Pong pong tree (Cerbera sp.), the squarish ones of the Nyireh (Xylocarpus sp.) , the oval shaped one of the Sea almond (Terminalia catappa). The reddish flower-shaped things are not flowers but a part of the seedling of the Tumu (Bruguiera gymnorrhiza). And of course the long seedling belongs to a mangrove tree.
Alas, an uprooted gnarled seafan. The seafan is a colony of tiny animals, and this one seemed to be still alive. What looks like a discarded drink plastic bag was entangled in it and might have caused it to come loose and drift ashore. Oh dear.
Also freshly uprooted, a candelabra seafan. It is quite commonly seen in this area. Kok Sheng later 'planted' these uprooted sea fans back into the water. Hopefully they will recover.
We also came across some dead fishes. There was one very large, very dead and very smelly long fish on the high shore. We also saw one that looked like a Pomfret, and a Tripod fish. In December last year, there was mass fish deaths in the area. Let's hope these dead fishes are not an early sign of a similar event this year.
This shore is heavily harvested. Today I saw a woman with a small 'cangkul' vigorously digging many holes in the seagrass meadows. A man slowly walked up and down the shore, meticulously digging up what looked like bivalves with a garden fork. Someone was using a cast net in deeper waters, while fishing was going on at the rocks.
The series of holes in the seagrass meadow dug out by the woman.
There was also a large abandoned net on the shore, as well as several abandoned fish traps.
As we were leaving at sunset, I noticed several of these tiny orange things actively looping and crawling among the barnacles on the rocks. I have no idea what they are.
We had a muted sunset and a mostly rain-free trip.
We don't very regularly visit this shore and my last trip here was in July. Let's hope this marvellous shore continues to survive.

More about our trip by:
  • Kok Sheng with a nudibranch he found just before we ended the trip!
  • Rene on facebook with all kinds of echinoderms that we missed.

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