Sunday, August 17, 2008

Changi shore with lunar eclipse

Today while we were at Changi for a predawn intertidal trip, we noticed something weird with the moon. A low spring tide occurs either during full moon or new moon.

How come the moon was a cresent this morning?

Liana revealed to us it is actually a rare event: a lunar eclipse! This photo was taken at 4.37AM.

At 5.00AM sharp, you can see more of the elipse effect. The dark part covering the full moon is actually the shadow of the earth.

However, the lunar eclipse is only a partial one. At 5.26AM, you can see that the eclipsing shadow is retreating away from "engulfing" the whole moon.

What has the moon got to do with low tide trips? Well, it's nice to witness a lunar eclipse personally after about 5 years but the moon is the main reason for the pull of low tides and high tides on earth through its gravitational effect. Without the moon, we will not have variations of tides, which means no super low tide to reveal the gems of the shores.

Back to the shore, Liana and Yuchen found this dead shark!

It takes very little time for these snails to feast on the shark buffet.

I encountered a much much larger snail: a noble volute!

This venus clam seems to have caught our attention today. According to Ria's Chek Jawa online guide, "Like many other bivalves, clams are filter feeders. They lie buried in the sand and extend their siphons to the surface at high tide. They use their siphons to suck in water and filter out microscopic food. The water also brings fresh oxygen to the animal."

This is the siphon that sucks in water and filters for food. Can you see the filter tentacles?

We were amazed how meaty the venus clam is. Exactly! Clams are among the favourite seafood of people everywhere. However, clams may be affected by red tide and other harmful algal blooms. Such clams can then be harmful to eat.

I witnessed for the first time how the clam suddenly extended its foot out and leap across the sand. Unfortunately, I couldn't capture the photograph sharply, this is a consolation to share with you guys :-)

Today's trip was primarily for my sand star project and also to look for button shell recruits. Indeed, Ria found a small patch of new recruits! Yay.

There were many different types of sea cucumbers at Changi.

Some are weird looking which we don't really know what the id is.

This is yet another unidentified sea cucumber.

And its underside.

Interesting, this has been seen at Cyrene Reef before and I've found at Chek Jawa as well. The photo above is taken from Chek Jawa.

I like the patterns of the feeding tentacles of this warty sea cucumber. It is so brillantly colourful!

This is yet another set of tentacles, belonging to the ball sea cucumber.

This cucumber looking animal is actually an anemone that is detached from the sand.

Soon it was time to leave the shore to head to Changi Village for some breakfast.

We encountered many beautiful parakeets.

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