Black Backgrounds

Last year I gravitated to macrophotography – in part because of the mostly bad viz, and in part because of the lack of outings to deeper/more interesting dive sites. Although through necessity, this was not really a problem, as biodiversity is greater at the small scale and I find macrophotography a bit easier than wide angle photography (especially as I am not usually floating through crystalclear, sunlit waters with many ‘charismatic’ animals). One macro trick is to use black backgrounds, avoiding the clutter of gravel, seaweed and assorted debris around the subject. For this you need to light the topic with a strobe and have open water behind it (which cannot be lit up and hence remains black). (Another strategy is using a snoot but I never managed to get that working…) Most recent posts feature examples of this technique but here are three pics I did not get round to posting. Descriptions of animals can be found in the captions.

The black background method also works for wideangle photography. As a bonus I am reposting a collection of old jellyfish photos.

What is a seaslug?

A nudibranch, a snail and a seaslug crawl into a bar…no seriously, what actually is the difference between these three types of molluscs? According to Kerney and Cameron (1979), those animals that cannot fit into their shell are called slugs, and those that can are called snails (definition brought under my attention by Ian Smith, see his amazing species accounts of British molluscs on flickr: Morddyn). Seaslugs either have an outer shell in which they cannot retract, an internal shell or no shell at all. The Solar-powered seaslug (Elysia viridis) pictured above is a species without a shell that is an example of a seaslug. Nudibranchs are a type of seaslug with ‘naked’ (nudi) gills (branchs) on their back. Nudibranchs never have a shell (although many have one when they are a larva). Books on nudibranchs often include seaslugs and sometimes they even feature snails! This happens when these species are related to seaslugs (the ‘lathe acteon’ or ‘beer barrel’ Acteon tornatilis is an example of that – a goal of this year is to take a good photo of that species). I have posted a range of photos on here as an illustrations of seaslugs (or not!); read the captions for species info.

Two Portraits

Just a really quick post featuring two characters I encountered last week. Above a Topknot (Zeugopterus punctatus), a little (<10 cm) flatfish. Below a Seahare (Aplysia punctata), an ophistobranch mollusc which is enjoying a bit of a population boom at the moment. Been in a bit more lately with so-so results but hope to post more soon.