19 April 2010

Changi: studded with pink sea urchins!

Today, the seagrasses at Changi were sprinkled with small pink sea urchins!

Here's some of the little prickly pink balls I saw, well embedded in the lush seagrass meadows. These are Thorny sea urchins (Prionocidaris sp.), also called pencil sea urchins. Unlike previous visits, we didn't see any White sea urchins (Salmacis sp.), which at other times can dominate this shore. Do these sea urchins take turns coming into season?
Changi is a great place to spot echinoderms, a group of marine creatures that include sea stars and sand dollars. And there were lots of Sand stars (Astropecten sp.) and Cake sand dollars (Arachnoides placenta) on the sandy stretches among the seagrasses. James also saw a dead Laganum sand dollar (Laganum depressum) but we didn't see any live ones.
I also saw one small sea star which is probably a young Cake sea star (Anthenea aspera). Here's close ups of the upperside. And the underside with the typical bivalved pedicellariae of this species.
Another kind of echinoderm are sea cucumbers. We saw buried smooth sea cucumbers, ball sea cucumbers (Phyllophorus sp.). As well as several of what seem to be See-through sea cucumbers (Paracaudina australis), oddly, floating about in the waves.
Buried in the sand bar was a bright orange sea cucumber that looks like the Remarkable sea cucumber (Holothuria notabilis), which usually has a more drab dark and light pattern.
There were lots of little Pink warty sea cucumbers (Cercodemas anceps) and really small Thorny sea cucumbers (Colochirus quadrangularis). Often smaller than even a blade of Spoon seagrass, these animals are commonly seen here. Alas, I didn't see any Garlic bread sea cucumbers (Holothuria scabra), but the tide wasn't very low so perhaps they were further out in deeper waters.
Changi is also home to many different kinds of sea anemones. The yet-to-be-identified Tiger sea anemone with red spots on the body column is so far only seen on Changi and Chek Jawa.
There were also lots of large swimming anemones (Boloceroides mcmurrichii) attached to seagrasses, as well as several Tiny carpet anemones (Stychodactyla tapetum), which are not baby carpet anemone but a small species.
And I saw one large Hermit crab sea anemone, that is usually stuck onto a shell occupied by a hermit crab. This one, however, was stuck to a bit of litter. It contracted into a ball when I tried to look under it.
Seagrass meadows are a great place for little animals to find shelter and food. These include all kinds of crustaceans: Well camouflaged elbow crabs (Family Parthenopidae) skulk among the seagrasses with their elongated pincers wide open. While there were lots of little Flower crabs (Portunus pelagicus), there was a tiny swimming crab of another kind hiding in the empty shell of a dead Fan shell. A kindly passerby handed us a Spotted moon crab (Ashtoret lunaris) "for you to photograph", he said, reminding us to put it back after we were done.
And there were tiny little shrimps that grow up to be our favourite seafood, well camouflaged among the seagrasses. And lots of little hermit crabs busy doing hermit crab stuff in the meadows.

We also saw several skinny pipefishes among the seagrasses. There are times when the meadows are crawling with these fishes and then they are not seen again for a long time. I'm not sure why. These fishes are related to seahorses and look like stretched out seahorses.
Speaking of seahorses, with Chay Hoon around, we can be sure to see one here. And indeed, she spots this little black Estuarine seahorse (Hippocampus kuda).
It doesn't seem to have any markings so it might be one that Collin has yet to mark in his seahorse study.
There were also lots of Window pane clams (Placuna sp.) today! James also spotted an Olive snail (Family Olividae) and Ball moon snail (Polinices didyma). Although the tide wasn't very low today, we still managed to see a lot of interesting marine life on Changi!

The seagrasses at this stretch seem to be doing well. The small patch of Needle seagrasses (Halodule sp.) have expanded greatly and thickly cover large areas of the high shore.
Here's a closer look at Needle seagrass.
The other kinds of seagrasses seen here include Spoon seagrass (Halophila ovalis) which have very large leaves here. And the pretty Fern seagrass (Halophila spinulosa).
There is a great deal of dead seagrass leaves washed ashore today. I'm not sure what this means.
On some parts of the shore, large pieces of wood and other debris have started to build up.
With many plastic bags that look like they were snack packets. Probably improperly disposed of by beach goers.
Chay Hoon also collected some abandoned fishing lines complete with hooks.
Let's hope people are kinder to this marvellous living shore right on our mainland, home to many plants and animals that are no longer commonly seen elsewhere in Singapore.

One of the rewards of a morning trip is a nice sunrise!
Tomorrow, one more morning trip!

Other posts about this trip

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