Sunday, 16 March 2008

Introducing our nudibranchs! 「シンガポールのウミウシ」

Have been dragging out this post for like ages now, especially since I wanted this to be part of my IYOR mini-project series.... Guess that would have to wait (yet again), so that this entry doesn't end up being one of my to-be-blogged-but-never-made-it-onto-ASHIRA entries...


Be it while walking the intertidals or while diving here in Singapore, the one organism that never ever fails to intrigue me (no matter how many times I see them) are the nudibranchs and their fellow seaslug relatives. Definitely WAY WAY WAY sexier than their landlocked slug relatives!
nudibranch photo pile
The word "nudibranch" is a mix of Latin and Greek, meaning "naked gills". So these little sluggies that I love so much are actually just shell-less snails! In fact, thery ARE related to marine snails and some of their opisthobranch (Greek for "behind gills") relatives still retain some sort of shell. But to me, nudibranchs are pretty much butterflies of the sea. Their colorfulness, graceful swimming, and their widespread appeal to divers all over the world, just seems so butterfly-like. It's not surprising that I also find butterflies fascinating! =^-^= That's a story for another time... Let's get back to introducing some of these colorful critters found in our tiny island locale.

(1) Jorunna funebris ブチウミウシ
oreo cookie nudi (1) IMG_1754 Jorunna funebris
Those who follow Neville Coleman's books on nudibranchs would know this bloke as the funeral Jorunna. I prefer to call it "oreo cookie nudibranch" - because it reminds me of many Oreo cookies with all their creamy goodness spilling out in a great big pool! These nudis are commonly found in tidal pools when the tide is out, as well as when diving, and there are times in the year when we are really lucky to see them in the process of procreating! While some people with more sensitive skin are allergic to sponges, this species FEEDS on blue sponges. Thinking of the spicules (glass-like pokey bits) found in sponges, I can only imagine how tough their mouth parts and stomach are!

(2) Glossodoris atromarginata キイロウミウシ
IMG_2494 Glossodoris atromarginata IMG_1101 Glossodoris atromarginata
Another species of nudibranchs that also feed on sponges is the black-marginated Glossodoris. Like the Jorunna funebris, it is also a commonly seen denizen of our coral reefs. A literal translation of its Japanese name can be taken to be "yellow colored nudibranch", and from the photo on the right I am sure you can tell why! The main body color ranges from a very pale yellowish off-white to the nice creamy butter yellow seen above.

(3) Pteraeolidia ianthina ムカデミノウミウシ
IMG_1951 Pteraeolidia iathina IMG_1932 Pteraeolidia iathina IMG_1110 Pteraeolidia ianthina IMG_0399 blue dragon [Pteraeolidia ianthina]
Serpent Pteraeolidia, is known locally as the blue dragon, and can sometimes be mis-identified as a Flabellina sp. as they look rather similar at first glance. Unlike the first 2 nudis introduced above, this species of nudibranchs possess zooxanthellae, and can photosynthesize, just like hard corals and giant clams!! They are extremely common and as many as 15-20 individuals can be spotted in a single dive or approximately 40 minutes!! I kid you not!! Given that our local waters are NOT known for their sparkling clarity, you are probably wondering how they managed to proliferate if they just photosynthesize... Just like hard corals and giant clams, the zooxs are not the sole food source of the blue dragon. They also feed on the nasty stingy hydroids that a really a dime-a-dozen here. Sometimes we even spot some small juveniles that are mostly white, lacking the zooxanthellae (see below).
IMG_1575 Pteraeolidia ianthina IMG_0378 juv blue dragon [Pteraeolidia ianthina]
That's all for now. Would definitely be back with more slug goodness!! More photos of nudibranchs and other seaslugs can be found here:

1 comment:

ria said...

Wow wow wow! Thank you for the fabulous article.

I hope you don't mind that I have (again) shamelessly advertised it on the iyor blog.

Looking forward to more delightful articles about these fascinating creatures!

Thank you once again!