Lately, Underwater, on Planet Earth: Jellyfish – Filefish Deathmatch

Last week, I had the pleasure of diving in the southernmost spot I have dived, ever. This was on the Morington Peninsula near Melbourne in Australia. Melbourne is located on a large bay, Port Phillip Bay, and fortunately, despite the large city nearby, the ocean in the bay is quite healthy. With two friends I headed to Rye and did some dives under the popular wooden pier in this vacation town. It was very interesting to observe a number of small filefish (called “leatherjackets” in Australia) feeding on the abundant jellyfish. A very cool spectacle! The fish were attacking the jellies in small groups, and the some of them even swam into the cnidarian’s bell. They looked like a bunch of puppies playing between lace curtains!

Yummi! Jellyfish for lunch.

Yummi! Jellyfish for lunch.

Of course I tried to get some shots of this cute fish behavior, which wasn’t easy. Jellyfish are hard to photograph, and this is what you have to do: hit them with your strobes sideways. The almost completely translucent jelly bodies will not reflect much light – but it’s possible to get diffracted light hitting them from unusual strobe angles onto your camera sensor. What is an “unusual angle”? That’s hard to define, since the position and orientation of the jellyfish is always changing, especially if it’s in the slightest current or surge. Try angles around 90°, or even more (back-lighting the jellies). Also, try not directly aiming at their watery bodies, but rather aiming your strobes tangentially. Just don’t light them straight frontally, because then you will likely not see much of the jellyfish in your images.

Fish behind a veil.

Fish behind a veil.

Also, as usual when photographing animal behavior, don’t scare the animals! In this case, there is no danger of scaring the jellyfish. But I had to treat the leatherjackets with extra respect. These fish are usually found close to the substrate, in-between sponges or in rock crevices. They enjoyed nibbling on the jellyfish, but were clearly uncomfortable in mid-water. Once during my approach to one of the leatherjacket – jellyfish death matches, I swam slightly too fast and all the fish took off for a hiding place on a pylon of the pier. Fortunately, other leatherjackets were feeding on other jellyfish, and I had more chances: What I had to do was float – barely kick – towards the fish, and then press the shutter down. The frog kick always helps – so would a rebreather for avoiding noisy bubbles. For now I am holding my breath when approaching these skittish fish – kids, don’t do this when changing depth, of course! And, all of that with the strobe arms already adjusted to the aforementioned odd angles – I don’t want to need to fiddle with them when close to the leatherjackets.

Lots of leatherjackets enjoying in, on and around a jellyfish.

Lots of leatherjackets enjoying themselves in, on and around a jellyfish.

I hope you enjoy the pictures of this somewhat unusual act of natural history!