19 June 2019

Explosion of Giant sea stars at Changi

This morning, I saw lots of huge Eight-armed Luidia sand stars at Changi! My first time seeing this.
Eight-armed Luidia sea star (Luidia maculata)
The shore was NOT taken over by clams (a relief) and seagrass situation seems similar to our last survey. We saw lots of colourful marine life.


The sea stars were very large! My foot next to one for scale. I stopped counting after I saw 30 individuals. I saw them at the point which seems to now be mostly bare sand. I only counted those I could see on the mid shore, there are probably many more in deeper waters. I'm  not sure why there is such a large number of them.
Eight-armed Luidia sea star (Luidia maculata)
These sea stars can move quickly and some were quite active, flailing their arms and 'walking' quickly on the sand. They are predators. So there must be a good source of their prey for there to be so many of them in such vigorous health.
Eight-armed Luidia sea star (Luidia maculata)
But these sea stars are also very fragile. If they feel threatened, they can purposely drop off or fragment their arms. I saw a patch of arm fragments. Not sure what  happened.
Eight-armed Luidia sea star (Luidia maculata)
There were also many other creatures on the shore, especially echinoderms. There were a lot of Pink warty sea cucumbers and some Thorny sea cucumbers. I saw a few Sea apple sea cucumbers, Garlic sea cucumber, Ball sea cucumbers. I saw several large White sea urchins, widely scattered. I didn't see many sea stars: a few tiny to small Biscuit stars, in the sandier areas, a few Plain sand stars. I didn't see any Common sea stars. During our last survey in Jul 2018, we saw lots of feather stars and Black sea urchins. I didn't see any today.
The ground has become very firm and is no longer soft and silty. I saw a few  Common cerianthids, some small and large Haddon's carpet anemones, on Big hermit hitching anemone, one Common peachia anemon. But no Tiger anemones. I saw many Sea Pencils, and some Flowery sea pens. I didn't come across other kinds of sea pens. I also saw one small Ball flowery soft coral.
I saw one pair of Mangrove horseshoe crabs. On our last survey in Jul 2018, we saw many more.
Mangrove horseshoe crab (Carcinoscorpius rotundicauda)
It was good to also see one Big-head seagrass octopus. It was hiding in a broken glass bottle. Unfortunately, these creatures are  heavily harvested by fishermen for bait. This morning, there were four people out with buckets and a headlamp slowly searching the shore. We didn't get a chance to chat with them to find out what they were collecting.
Big-head seagrass octopus
It was a relief to see that the shore was not taken over by clams like another part of Changi that we surveyed in Feb 2019. Although there were some Fan clam shells, they were small and scattered. There were some thin sheets of Little black mussels on the rocky areas. I saw two Calf moon snails, a Hairy sea hare and a Spotted sea hare.
The seagrass situation seems similar to what we saw in Jul 2018. The meadows were mostly Spoon seagrasses (large and small leaf blades) with scattered and patches of Needle seagrass (narrow leaf blades). I didn't come across Fern seagrass. The small patch of Smooth ribbon seagrass where the pipes used to be are still there, first observed on our Jun 2016 survey. But I didn't see clear dugong feeding trails today.
The rocks in front of Changi Point Ferry Terminal were covered in corals and sponges!
Living rocks opposite Changi Point Ferry Terminal
There were lots of Zebra corals on all the rocks on the lower shore.
Various marine life on Changi Beach
There were also some colourful sponges and other encrusting marine life on the rocks.
Nudibranchs feed on such animals so it's great to see Atagema intecta (black blob near black sponges - does it eat the sponge?) and a well camouflaged Thordisa villosa - spotted by Shawne, Bravo!
The tide turned at sunrise!
Sunrise over Changi
Let's hope these interesting shores remain well until we can visit again in a year's time.

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