Whales in danger - take action and fight for ban

Whales under Threat

United States Urged to take a strong stance against Whale Hunting


If you haven't heard yet, there's actually a chance that the ban on whaling could be repealed.  I feel strongly, that that would be the wrong step to take.


Diving underwater with giant jellyfish

Diving Underwater with giant jellyfish

Underwater photographers hit the jackpot


It was my 5th day of blue-water diving over the last 3 weeks for pelagic jellyfish in Southern California, and my 2nd charter I was bringing out to experience the jellies.


Dropping down our line, at about 70ft the water was getting clear. The ocean floor was 1,000ft below us.


Wow, we really hit the jackpot. A giant 15ft purple jellyfish, with an entire squadron of fish being sheltered, started to swim by. 


Blue-water Diving for Pelagic Invertebrates

Blue-water Diving for Pelagic Invertebrates

Underwater Photography in 2,000ft of water

By Scott Gietler


After finding very unfavorable conditions on shore, our boat captain suggested we try a "blue-water" dive and see what comes by. The idea sounded very exciting, and I quickly said "yes!".


We were near Point Vincente, in Los Angeles County California. We then motored 4 1/2 miles off the California coast towards Catalina Island, where the bottom was 2,000ft below us. The boat engine was turned off, the anchor was dropped down 80ft into the depths, and we started suiting up.


large salp underwater photo with diver

Diver with salp chain, on a blue-water dive off the coast of Los Angeles.


Scared of the Underwater Depths

What would happen? Would I drift into oblivion? Sink to the bottom? Get eaten by sharks?


The boat just slowly drifted. I jumped into the water and descended. Swimming to the anchor line was easy, because that boat and I were moving together with the current.


I slowly descended. Hanging on the anchor line at 60ft was an unbelievably relaxing experience.  The dive was surprisingly exciting, because you never knew what would come by. I saw dozens of pelagic gastropods, some pelagic Tunicates, many comb jellies and a few Cnidarians (Jellyfish). All are excellent underwater photography subjects.


Although I was attempting a "blue-water" dive, the water was quite green, with heavy "snot" in the water. However, it did clear up a little at 75ft depth, and the species I saw down there were different.

large purple jellyfish on a bluewater dive

If you are lucky, large jellyfish can be spotted on blue-water dives during certain times of the year. Tokina 10-17mm lens.


Drifting away from the line

Letting go of the anchor line was not a problem. The boat and I were drifting together. Because of my drysuit and camera, I travelled slightly faster in the current, (or maybe the wind pushed the boat faster?) so I preferred to hang on to the anchor line. If I ever lost sight of the line, I would have to surface and swim to the boat, which I felt comfortable doing.


Maintaining my buoyancy was quite easy, and I felt like my breathing was relaxed and gas consumption was low. Unfortunately there were no sharks to be seen.


Although I never saw anything large, it was a great experience that I can't wait to do again. Next time I might try my macro lens for sharper photos. I think my macro lens behind my dome port might be perfect. But of course, then a whale will swim by.


My fisheye lens was a little too wide for most of what came by, but I made the best of it. The heavy particulate meant lots of backscatter, and lots of playing around with my strobe positions. Clear pelagics can be hard to focus on, so for much of the time I pre-focused my lens on the anchor chain a couple inches from the dome port as an experiment, and then switched my lens to manual focus so there would be no "hunting".


Normally I tell people to shoot "upwards", but on this dive I found out shooting downwards gave a darker background, which looks better with these clear subjects.


How to do blue-water diving - an FAQ

Follow these simple steps:

1) Go out on a private boat or a small private charter where the captain agrees to take you blue-water diving

2) Motor out to the open ocean. 500ft - 2,000ft depth is a good range. I like to target the "shelf" areas that drop off more rapidly than other areas. Study the nautical charts before you go out, to find a good area.  Hopefully you are going where the jellies are!  Jellies may be seasonal. Now (April) seems to be a hot time in Southern California. Morning may be better as there is less wind, but on my last dive I started seeing larger jellies in the afternoon.

3) Drop the anchor line down 100ft, or tie a weighted 70 or 80ft line to the side of the boat. Jump in the water and follow the line down. Make sure someone stays on the boat. Stay down as long as possible for maximum jellage.

4) Make sure you read the safety tips below! You may want to make yourself a tether, read on.



Safety during your blue-water diving

  • I felt very safe and relaxed on the dive. If you're concerned about floating away from the anchor & boat (this could be *really* bad if you and the boat move differently in a current or the wind), either keep hold of the anchor line, or attach yourself with a tether. For mild currents without much wind, you are moving at a similar speed as the boat, so there is not much danger, because if you lose sight of the line you can always just surface and swim to the boat. If the wind picks up, the boat will start moving faster than you, so you will probably want a 10-15ft tether.
  • To make your own tether, just buy a 10ft to 20ft strong rope, with a strong clip on one end (to clip to your D-ring), and a carabiner on the other end to go on a anchor line or chain. You'll probably have to know how to make some good knots to put all that together also, luckily a friend made my tether for me. I've used the tether on 2 out of my 7 dives, only when I feel like I lose the anchor too quickly when I let go of it to photograph a jelly.
  • Swimming away from the anchor line and almost losing sight of the line can be scary, and it can happen easily with an exciting subject like a Pelagic Gastropod. Try it out near the surface before you descend, so you know what it's like.
  • You'd be surprised how far you can "pull" the anchor line towards a subject if needed.
  • As you descend down, think about how you would dump your weights if you ever had a serious buoyancy problem (this is really a last resort though). Run the scenario through your mind a couple times, and practice the motion with your arm. This way you know what to do if ever had an emergency and started sinking too deep. Also practice orally inflating your BCD.
  • If you are on Nitrox, you must be mentally prepared to drop your weights if you ever lost buoyancy (BCD malfunction, puncture in the BCD) and dropped below your MOD.
  • Don't go in if there's a lot of surge or it's very windy.
  • Make sure you have a whistle and safety sausage on you.
  • If the boat is moving, once you get underwater take a compass bearing so you know what direction to swim during your safety stop if you do lose the anchor. Let go of the anchor line; as you drift away, take a bearing back to the anchor line - that's the direction to remember. Now swim back to the line.
  • If you do lose the anchor, or your tether breaks, don't panic- swim in the direction you had measured with your compass, come up quickly (but safely) and swim back to the boat.


Underwater Photography Tips for Blue-water Diving

  • Bring a macro lens for small pelagic invertebrates, wide-angle for a chance rare encounter with fish, sharks, whales, molas, etc. As you see in this report, a wide-angle lens can also be used for close-focus wide angle photography of small invertebrates larger than 5cm.
  • Take frequent test photos of the anchor line to try out your settings and strobe positions
  • Hang out at different depths to see different species. I like using Nitrox because there's cool stuff at 70ft depth. 

For more information and a complete set of underwater photography tips, read about photographing Jellyfish and Salps


pelagic heteropod

Pelagic Gastropod,a Heteropod Carinaria japonica. All photos on the dive taken with a Nikon D300, Tokina 10-17mm fisheye at 17mm, F11, 1/320, ISO 400, cropped, heavy particulate in the water. The shell is at the top, the mouth at the bottom. In the middle is its pen*s (reproductive organ), so you can tell it's a male!


pelagic heteropod underwater photo

Pelagic Gastropod, a Heteropod. The bright body part at the bottom center that looks like an oyster is its internal shell. The black spots at the top are its eye, this species is a visual predator. The bright area in the center above the shell is it's mouth and proboscis, which has radula and teeth.


comb jelly

Comb Jelly, Leucothea pulchra


larval stage tube anemone

Larval stage tube anemone


jellyfish with barnacles

Jellyfish with several white crabs, and a white pelagic barnalce in the middle of the top of the bell.


mola mola sunfish underwater photo

Mola-mola, a nice find in the open ocean!


venus's girdle

Venus's girdle, a Comb Jelly


sea butterfly

Sea butterfly, a pelagic gastropod. Nikon 60mm behind a compact dome port


I saw several Dolioleta gegenbauri, a 5cm long Pelagic Tunicate (but not a Salp, different order) that has a large appetite. Although they floated motionless, when approached they rapidly moved away, making photography very difficult.


Pelagic doliolid

This Pelagic Tunicate, Dolioleta gegenbauri, looked more like a worm, and swam like a jittery snake.


Further Reading


Guide to photographing Jellies and Salps

California Marine Life

Reducing Backscatter

Marine Taxonomy Chart


Leafy Sea Dragon

Leafy Sea Dragon

Phycodurus eques - habitat, range, life cycle, dive sites

By Scott Gietler



The Leafy Sea Dragon, Phycodurus eques, is one of the most beautiful fish in the world. Seeing one underwater is an amazing experience, you can watch these fish for hours while diving underwater. Leafy sea dragons are in the family Syngnathidae, which also includes seahorses and pipefish, and its close relative the Weedy sea dragon.


leafy sea dragon

Leafy sea dragon photo, Adelaide


Nudibranchs, aka Sea Slugs

Facts, Habitat, Diet, Underwater Photography Tips and Dive Sites

By Scott Gietler



Nudibranchs are great subjects because they usually stay fairly still, and they can be very colorful. Always get the rhinophores in focus. The rhinophores resemble two "antennae" that stick up from the front of their head.


Shoot low, from the front or the side, not from above. For dorids, it is important to wait until the gills come out. Try to get the food source in the photo. Pay careful attention to the background so the nudibranch looks separated from the rest of the photo. Play with the lighting. Gills out, gills & rhinophores in focus is usually considered a great shot, but it can be difficult to get both into the depth of field, and other compositions work well also.




In this shot of 2 Cerastoma nudibranchs, I was able to get all 4 rhinophores in focus. F18, 60mm lens. With a compact camera, shoot at F18 for maximum depth of field.




hopkin's rose sea slug

Here's a "classic" nudibranch composition - get down low, shoot the nudibranch at an angle, get the rhinophores in focus. Photo by Kevin Lee.




Getting low can be difficult, but it pays off. You usually have to find a nudibranch that's on a little hill, like this one, and then lay right on the ground. F18, 1/125th, 105mm lens.




Best dive sites for Nudibranchs

"Nudibranch hot spots"

Here are some excellent dive locations for sea slugs and nudibranchs.

  • Contact me if you know of other nudibranch "hot spots."


Nudibranch photography tips

  • Get low, get the rhinophores in focus. If the gills have retracted, be patient and wait until the gills come out.

  • Get close and try to fill the frame.

  • Understand how your aperture controls your depth of field.

  • Think about the kind of background you want - black background, background sharply in focus, or a background nicely blurred. All choices can make great underwater photographs.

  • Learn how to position your strobes for front-lighting and side-lighting. Different sea slugs look better in different kinds of light.

  • Use your histogram to avoid blowing out colors and highlights. View your histogram as a 3 color histogram if possible.

  • To identify a nudibranch, try to get the gills, rhinophores, oral tentacles, etc. in sharp detail - see the anatomy section below.

  • If your camera allows you to move your focus points, choose spot-focus, compose your photo, and move the focus point until it lies over the rhinophores of the nudibranch.

  • Read about supermacro underwater photography, to photograph very small nudibranchs.

  • Please don't harm a sea slug just so you can get a better photograph, or move them from their environment. Sea slugs feed on very specific food sources.

  • Compact camera users - read the lens selection section below, to understand how zooming in and zooming out affects your composition and background.

  • Also read our article 'Essential Tips for Nudibranch Photography'


janolus nudibranch

Janolus nudibranch with a black background,  Catalina island, California. 60mm lens, F18, ISO 250, 1/250th


Nudibranch Anatomy & Taxonomy

Nudibranchs are animals in the phylum Mollusca, class Gastropoda - which means, like snails, they are Molluscs and Gastropods. Technically, Nudibranchs are a sub-set of animals called Opisthobranchs (sometimes call Sea slugs). Which means all nudibranchs are sea slugs, but not all sea slugs are nudibranchs. Got it?

Most, but not all, Nudibranchs can be classified as Aeolids or Dorids.

Dorids have 2 rhinophores and plume-like gills. The gills are also known as a branchial plume.


nudibranch showing rhinophores and gills

The 2 rhinophores of this white Dorid nudibranch are on the left, sticking up like antennae. The gills are on the right, and will retract if the animal is startled. The skin covering the top of the dorid is called the mantle, which is this case is covered with small bumps.


Aeolids have oral tentacles, rhinophores and cerata. Some Aeolids can store nematocysts in their cerata, after they eat a Cnidarian such as a hydroid or anemone.


Aeolid nudibranch showing oral tentacles, rhinophores, and cerata

In this Aeolid, you can see the two large oral tentacles in the front, and the two smaller rhinophores sticking straight up on top of the head. The brown cerata cover the rest of the body, flowing backwards in this photo. Some nudibranchs can lose their cerata when harassed.


Nudibranch Natural History

Most nudibranchs feed on only a particular hydroid, anemone, sponge, bryozoan, or tunicate. Underwater photographers often find a nudibranch by locating it's food source. Some nudibranchs that eat hydroids or anemones can store the nematocysts of their prey, using it for defense later on. Nudibranchs generally crawl around looking for food, but some can be surprising mobile and launch themselves into the water column when their feel threatened.

Some nudibranchs, like some Phyllodesmium species, are solar-powered, getting energy from symbiotic zooxanthellae that they absorb, much like corals do.

Nudibranchs are hermaphrodites, willing to mate with any other member of it's species, usually. Nudibranchs almost always begin their life as free-swimming planktonic larvae, and their lifespan is between 2 months and 1 year for most species.


Lens selection for Nudibranch photography

  • Compact camera users - should zoom out to get the effect of the 60mm lens listed below. Zoom in all the way to get the affect of the 105mm lens. Wet lenses can give you additional macro capability for smaller nudibranchs.

  • 60mm lens on a cropped sensor camera (90mm in 35mm equivalent) is good for photographing nudibranchs in their habitats, in-situ photographs. Auto-focus is fast, night photography is easy, and you can get close to the subject. Also good for low-visibility dives. If you are using a compact camera, simply zoom out all the way.

  • 60mm lens + 1.4x teleconverter. Another excellent choice, especially if you think you might see very small nudibranchs. Slower auto-focus, but still useable on a night dive.

  • 100mm or 105mm lens - great for isolating a nudibranch, filling the frame and blurring out the background. Also good for nudibranchs deep in reefs, cracks, crevices, etc - due to the increased working distance. Can be more difficult to use on night dives. If you are using a compact camera, zoom in all the way to isolate the nudibranch.

  • Fisheye lens - this can be used if you get very, very close to large nudibranchs, for unique photographs that capture expansive backgrounds in the photograph.

  • Further reading on lens selection - supermacro photography, lens selection and composition, 60mm vs 100mm macro lenses


Dirona nudibranch with nikon 60mm lens

Dirona nudibranch photographed with my 60mm lens, F20.


Dendronotus albus nudibranch, 105mm lens

Dendronotus albus nudibranch, Nikon 105mm lens, F16.


Chromodoris coi, 60mm lens + 1.4x tele

Chromodoris coi, Nikon 60mm + 1.4x teleconverter, F22.


Janolus nudibranch photograph

Janolus nudibranch, head on composition. You need to get very low to get this composition, and align the nudibranch carefully. Using the 105mm lens helps to isolate the subject. Shot at F13, photo by Mike Bartick. Mike used a custom +10 diopter for this shot, and waited for the nudibranch to crawl towards him.


Featured Article


Further Reading

Best dive destinations for underwater photography

Muck and macro diving critter list

Super macro underwater photography

Macro underwater photography

Underwater settings for macro

Advanced underwater composition (with some good ideas for Nudibranchs)

Story Behind the Shot:  Melibe Nudibranch Congregation

California Sand Dwelling Nudibranchs

BEHAVIOR Captured:  Nudibranch Self Defense in Action


Nudibranch resources

Sea slug forum


Nudibranch ID forum

Inspirational Nudibranch photos by Kevin Lee

Marli Wakeling's Nudibranchs of the world

Jim Anderson's Scottish Nudibranch Page

Nudibranchs of the Mediterranean sea



Other Marine Life Articles

Leafy sea dragon - expert in camouflage

Bobbit Worm - ambush predator

Frogfish - Camouflaged ambush predators

Black Sea Bass - Gentle giants of California


Support the Underwater Photography Guide

Please support the Underwater Photography Guide by purchasing your underwater photography gear through our sister site, Bluewater Photo and Video. Click, or call them at (310) 633-5052 for expert advice!


Bobbit worm - ambush predator, Eunice aphroditois

The Bobbit worm, Eunice Aphroditois

 By Scott Gietler




The Bobbit worm, Eunice aphroditois, is a ferocious underwater predator. The bobbit worm, also known as the Eunice worm, can be found in Secret bay in Bali, Indonesia - Police Pier & Nudie Retreat in Lembeh, Indonesia - and Mainit Muck or Basura in Anilao, Phillipines. It likes sandy and gravel substrates, that you would find on "muck" dives.


bobbit worm underwater


The bobbit worm has light and chemical receptors that cause it to lunge at fish when it thinks they are nearby. It has 5 antennae that house these sensory receptors.

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