The big challenge in photographing animal behavior is actually finding it. The key is diving slowly. When divers race around, all they see are creatures reacting to the movement, usually swimming away. Hang in the water and breathe lightly, and soon marine life will get back to its business. Spend 30 minutes just watching at a cleaning station, and you will be rewarded with one of the best dives of your life — and some fantastic images.

Living Together

1. Symbiotic Snaps

Many marine species cohabit. These can be lifelong cooperations — like a shrimp and partner goby sharing a burrow — or one-way relationships, where smaller creatures are uninvited squatters on large marine life. An example of the latter is imperial shrimp hitchhiking on sea cucumbers. To tell their story you need both species in the shot, so don’t frame too tightly. Often these species have coordinated color schemes, which enhance image aesthetics. The best way to find these relationships is to learn them, so when you spot the large individual, you’ll know to look for the smaller, more secretive species too.

2. Precision Composition

Most cohabiting species tend not to run away, which is another reason they are so popular with photographers. However, you will still need patience to wait for them to clamber or crawl into a perfect position. The sea slug (pictured) is an algae eater, but I have frequently seen them on these common, colorful tunicates. I suspect they are feeding on a thin layer of plant life growing on the surface. For the picture to work, it must be about the slug and the tunicate. My approach was to frame up a pleasing pattern in the background and wait for the slug to slither where I wanted.

3. Depth of Field

To make the most of attractive patterns in the host species, the subject and the background need to be in focus. Shoot with the camera parallel to the background to make the most of the depth of field. Turn your strobes up so you can close down your aperture to maximize the amount in focus. Don’t place the smaller subject in the center of the frame; instead, compose it on one side, facing into the picture, letting the background patterns dictate your framing. 

Next Generation

Photographing reproduction generates some of the most spectacular underwater images; egg-laying species are the best place to start.

Beginner Tip:

To capture an interesting animal behavior that does not require a wealth of research, look for species guarding their eggs underwater. Although these critters are easily approached, zoom in or use a longer lens to capture photos of them. Typically in underwater photography, shooters want to get as close to the subject as possible for the best image quality, but with behavior, it is all about capturing a natural pose. This is easier from slightly farther away. Turn up your strobe, and move it a little farther out from your camera to compensate for the distance.

Intermediate Tip:

Anemonefish hide their eggs on a hard surface beneath the skirts of their anemone, and the eggs can be hard to spot. Look for anemonefish behaving more territorially than usual, or regularly disappearing under the same fold of the skirt. Once you’ve found the eggs, simply set up your shot, and soon enough you will have an adult in the frame for the perfect image.

Normally in underwater photography, shooters want to get as close as possible for the best image quality, but with behavior, it is all about capturing a natural pose.

Advanced Tip:

Anemonefish eggs usually take six to seven days to hatch. They start off brightly colored and get more silvery as the babies develop. Hatching happens after sunset. Once you have found a batch of eggs, return over a few days to record the development. The most common behavior is the parents fanning oxygen-rich water over the eggs with their pectoral fins.

Dr. Alex Mustard is a marine biologist who has been a full-time photographer since 2004. His latest book, Underwater Photography Masterclass, is out now. To see more of his work, visit amustard.com.