Metazoan

Last week I returned to Fly Point, Nelson Bay, for a few days of diving. The site has been beaten up over the last few years by storms and floods, but conditions were good and it was great to be back. Many of the regulars were there to welcome me – notable octopuses, inquisitive banded shrimp, an elegant turtle, and especially the astounding animal above – a nudibranch, Phyllodesmium poindimiei. Despite their near-impossible appearence, they can fairly often be found in the soft coral garden at Fly Point, round 14 meters down or so. They’re often 2-3 cm long. Last week I was seeing three or four on each dive. Whenever I find these, I take a lot of photographs.

How should one photograph such an animal? In general, I am a natural light photographer (“available light”). No flashes or beams. I want to work just with what’s already there, as much as possible. Several reasons for this: Gear can be smaller and you can swim faster; you don’t bother the animals as much; many scenes look more natural as the background light is similar to the foreground. And more fundamentally, the photo is more faithful to the world that’s down there, where this includes the light. But with tiny invertebrates like this, adding light can be revelatory. Much more structure appears, and the range of colors explodes.

So I have a “video light,” like an attached torch, more compact and portable than a flash (“strobe”). But turning it on now induces, under the water, a long chain of moral-aesthetic reasoning. The main factor is my concern that it is stressful to the animals. I’ve been on dive trips and seen people blasting tiny creatures with light for several minutes – pygmy seahorses, which lack eyelids, are often treated especially thoughtlessly. With these nudibranchs, I now tend to take a bunch of photos with natural light, then turn the video light onto its lowest setting for a dozen shots or so, and then turn it off again in response to an insistent inner soliloquy. But then wonder what masterpiece I might create if I gave the shoot another minute or so of added light. (It would be great to go back to the narrower aperture and faster shutter, too.)*

On this trip, the ethical back-and-forth was endless. Do I have reason to believe it bothers a nudibranch at all? They do have eyes, but very simple ones. Brightness would probably be confusing, but would it be unpleasant? Would a minute or so of blazing light be interesting rather than aversive? How could I tell? Does it make much difference to only use the lowest setting?

Setting aside the experience of the animals, will I gain more from the authenticity of a wholly natural-light dive? Will I take in the reef in a more holistic and accurate way? These questions were cast into relief by the fact that on day 2, I got into the water and realized that I had no choice – I’d forgotten to charge the light overnight, and although once this oversight would not have mattered, the battery is now so old that it has to be charged for every dive.

So far in this post, every photo has had some added light (using the lowest setting). Here’s a day 2 photo without even a photon added.

It did feel different to do the entire dive – the sort of dive where I’d usually use the light occasionally – with no added light. I knew I was not bothering the animals at all; that led me to be more relaxed.

This is also a natural light photo, from day 1, when the light (sun) was better.**

After getting out on the last day, I realized I might have inadvertently collected some useful data. I’d taken scraps of video with and without extra light. If the light bothers these animals, this might show up in their behavior – perhaps some agitated waving of those antenna-like rhinophores on the front. If there’s no observable difference, that would not show that the light doesn’t bother them. But if there is a difference of that kind, it suggests that light is at least having a stimulation-like effect, perhaps unwanted. It’s a start.

When I checked the camera, I found that I only had very small scraps of video that might be compared. These scraps are of the same animal. Here’s some video without added light:

And here it is with light added (lowest setting).

Superficially at least, there doesn’t seem to be a big difference. I should do a more systematic version of this test, trying different light levels, when I go back to Fly Point.

I’ve not explained the title of this post. Though I’ve not yet been able to work out the history of this nomenclature, a common name for Phyllodesmium poindimiei is said to be “spun of light.”

The Spun-of-Light Nudibranch.

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Notes

* I was once on a dive boat for a week and at one point a diver who had a very elaborate lighting rig had problems with it, and it looked like he’d not be able to use his lights for the rest of the trip. He was quite dismayed. I started offering to help him transition to natural light photography. This was very unwelcome, not just because he didn’t like me as a person, and not just because people with rigs like this often don’t like advice, but because (I think) there was something about the whole idea he wanted to resist. Bright lights underwater have an almost addictive quality.

** During day 1, I did, at one point, experiment with the light on low and also turned far away from the animal. I don’t think this photo was one of those, but the meta-data for the photo doesn’t rule it out.

The natural light photos are not “straight out of the camera” in any sense. All the photos have had some work.

What are the red threads and what are the orange clusters? I’ll do a follow-up post about this marvelous species.

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