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What’s in an obsession?

A sea pen, resembling an antique quill pen, at Lembeh. For scale, please observe the size of the grains of sand and you will see that the sea pen is rather small. This creature anchors itself on the seafloor and has various polyps that specialise in different functions, e.g. feeding by using nematocysts to catch plankton, reproduction, etc. (

By Asher Ang, K2 Lembeh Dive Resort

Original publication date: January 3, 2020. Updated: 24 May 2022.

One day, during a surface interval, my daughter asked me this question: “Pa, why are you so obsessed with sea pens? Whenever you see one you spend a long time looking at it, and keep on taking photographs of it. Why?”

So began a discourse about how the pen is mightier than the sword, not…

What do you do when you dive?

Apart from breathing and watching marine creatures go by, do you actually observe what you see? For me, the obsession with the sea pen began when one day I decided to stop and examine the creature for a moment, and behold, a smaller critter living on it. Oh, wait a minute, there were 2 of them. Enter the beautiful pair of porcelain crabs, Porcellanella haigee!

Porcelain crab, Porcellanella haigee, emerging from the root of a sea pen. This is getting really small.

The porcelain crab is said to not be a true crab, but a close relative of the squat lobster. My obsession with them goes beyond the discovery of a smaller critter dwelling in the midst of a small sea pen, but the knowledge that these wonderfully colourful critters, like their more famous porcelain crab cousins Neopetrolisthes maculatus and Neopetrolisthes ohshimai, are filter feeders!

So if you are not a photographer, stick around to observe how the porcelain crab raises its front bristle-like mouth piece to trap debris in the water and alternately bring the bristles to its mouth!

And if you are a photographer, the challenge is to photograph the critter with the bristles clearly visible fully extended in front of the crab.

OK, this is not the same fellow, but another porcelain crab Neopetrolisthes maculatus on a sea anemone doing filter feeding. The modified bristle-like mouth pieces alternately bring trapped debri to the mouth. The next time you see a sea anemone, would you look for the porcelain crab, and perhaps find a few more shrimps, along with the ever attendant anemone fish (clown fish, or Nemo).

The tiny porcelain crab Porcellanella haigee doing filter feeding. Again, grains of sand looking mighty big! Power of a macro lens going to about 1.4:1 (larger than life size on the sensor).

And so I explained to my then-teenaged daughter the discovery of the porcelain crab on the sea pen, and their feeding method. And soon we were lying down on the sandy sea floor, watching tiny sea pens for minutes at a go!

No doubt many of you will already appreciate the beauty of these porcelain crabs, but knowing a little about their living habits make observing them in the wild so much more interesting and makes Mother Nature so much more appreciable beyond the more superficial “cute” appellation.

Post-script, but no less important

One of those things a photographer benefits from is the ability to review the photos and, with a monitor, enlarge it beyond what I can normally see (with my myopic, presbyopia and cataract eyes).

I was so focused on capturing the bristles for the filter feeder Porcellanella haigee that I missed 2 things. Can you figure out what the 2 things are?

First, it’s a girl! Did you spot the eggs the little porcelain crab was carrying? I did not until I reviewed the photographs some days later. Second, the crab’s mate is around the corner, did you see him?


There are many excellent dive centres around Lembeh, either on the mainland side, or on Lembeh Island side. I am part of a team that directs the operations of K2 Dive Resort on Lembeh Island. If you have enjoyed reading this, and are considering going to Lembeh for your dive experience, perhaps you would visit the K2 Lembeh Dive Resort website?

The view of Lembeh Strait from K2 Lembeh Dive Resort. K2 Lembeh is named after the village in which the dive resort is situated in – Kelapadua (2 coconuts). We are a fully equipped boutique dive resort situated on the South side of Lembeh Island along the Lembeh Strait, Bitung, North Sulawesi. Our closest international airport is situated in Manado.

Live long and dive safe!


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