Blog Log, 26 July 2009

July 27, 2009

Sea slugs on the reef - Egretta nudibranch PHOTO: Jimmy Goh

Divers at Pulau Hantu enjoyed exceptional visibility today. Volunteer dive instructor Peimin said it’s the best it’s been since April! Sure am bummed I missed it once again. So here I am blogging vicariously (again) but feeling none less thrilled about what was spotted today on Hantu’s reefs! From shellfish to slugs, pipefish to seahorses and all critters in between. We’ve got an unusual perspective of the reef this weekend thanks to some extraordinary photography!

Flabellina nudibranch PHOTO: Jimmy Goh

Another volunteer dive instructor, Jimmy Goh, took time off to do a leisure dive with the group today, and thanks to him we have some wonderful close-up images of Hantu’s critters!

Scallop eyes PHOTO: Jimmy Goh

Did you know scallops have eyes? Yeap! About sixty primitive tiny bright blue eyes reside in rows along a scallop’s mantle edge to detect motion, light and dark.

Doto nudibranch on Giant hydriod PHOTO: Jimmy Goh

You can have lots of fun with a macro lens in Hantu’s waters because there are just so many opportunities for great subjects in our turbid waters, especially if you’ve got a keen eye! And Jimmy’s definitely got one! As a guide on our reef, Jimmy has spotted tiny thumb-sized octopuses and large stoic frog fishes that are masters of camouflage. In the photo above, is an absolutely tiny nudibranch about the size of a pin head. A Giant hydroid can grow up to two meters long, and these tiny slugs seem to blend perfectly into its “feathers”.

White allied cowrie on Gorgonian coral PHOTO: Jimmy Goh

Still on the subject of small stuff, the above is a allied cowie that has managed to blend so perfectly with the texture and colour of the gorgonian coral it shelters in.

Gorgonian or Sawtooth shrimp PHOTO: Jimmy Goh

Not so much tiny as it is thin, this Sawtooth or Gorgonian shrimp perches precariously onto a whip coral. This is a great shot of the creature because we are able to see its eyes bulging out of its body and its upturned nose at the bottom-left of the picture, as if it’s looking toward the camera. When being photographed, these shrimp like to “roll” over to the opposite side of the whip to hide from the camera. It takes that little for them to literally vanish from view!

Bubble shrimp in Bubble coral PHOTO: Jimmy Goh

I promise I won’t make you squint after this. Here’s another extraordinary photo of a Bubble coral shrimp. As you might be able to determine just by looking at it, these are very delicate creatures, that are also very beautiful to us at least! For protection, you can find them hiding between the stinging tentacles of corals and anemones. These critters are hard to spot, because apart from being transparent, they also snuggle in deep amongst the tentacles for safety.

Longsnout pipefish PHOTO: Jimmy Goh

Longsnout pipefish can be found crawling over stands of hard coral or the sandy seabed in search of small organisms in the water. They usually remain at a spot, allowing the current to bring food to them. They are sometimes spotted in pairs, and can grow to about 8 inches long. These pipefish have snouts much more pronounced than their cousins, the Seahorses and Banded Pipefish, and unlike them, they do not have a prehensile tail with which to attach themselves to a host.

Janss' pipefish PHOTO: Jimmy Goh

Much better than the picture I took several months back, the Janss’  pipefish is a stronger swimmer than its seahorse cousins and rarely comes into direct contact with the substrate. They can be found swimming under rocky overhangs, corals, or close to the floor of its reef habitat where it performs the role of cleaner fish and often feed on parasites and dead tissue from damsels and cardinalfish. What a beautiful find! A video of it lurking in a crevice on Hantu reef can be seen here.

Yellow prawn goby and Blind shrimp PHOTO: Jimmy Goh

Not just pretty to photography but also fun to observe and tricky to approach, prawn gobies and their blind shrimp partners have an unusual but very necessary relationship. In the photo above they both stand guard outside the burrow that they share, looking unusually calm! As their namesake suggest, blind shimp have poor eyesight but they have the might to shovel out debris from the burrow with their pincers. Obviously a goby would have a much tougher time with a job like shoveling  sand, so it stands guard at the entrance to the burrow, flicking its tail to warn the shrimp of approaching danger and hence to stay inside, or disappearing into the burrow altogether if danger is eminent! A video of the duo can be seen here.

Sponge detail PHOTO: Jimmy Goh

To wrap it up, here’s a close look at the structure of a sponge. The delicate network of sponges, looks fine and brittle because it is! The skeleton of a sponge is made up of scilica, in other words, glass! Yes, tiny tiny bits of glass. If you looked through a microscope, they would look like snowflakes. In order to identify a species of a sponge, scientists have to isolate each spicule or segment of the sponge’s skeleton to see its shape before they can figure out what species it is! Before the days of synthetic sponges, people used sponges from the sea for washing and cleaning!

Posted in Biology, Blog Log, Volunteers