Reef Predator Hunting Techniques

It's dog eat dog — or fish eat fish — on the reef. Predation by larger fish is a fact of life for members of the coral reef community, and this danger plays a large part in shaping many aspects of life there. Fish predators come in all shapes and sizes and include moray eels, jacks, groupers, frogfish, scorpionfish, and trumpetfish. Some of these predators use stealth or camouflage to approach close enough to launch a strike on their fish prey. Others prefer out-and-out pace, using their superior swimming speeds to overtake and capture their quarry.

How do predators operate on the reef?

The most important part of a predator's strategy is to get close to its prey. Close-range attacks, combined with the element of surprise, offer the best chance of success. Even so, it is estimated that far fewer than half of all attacks are successful. Prey fish have evolved over millions of years to be able to respond extremely quickly to any sudden disturbance. They are capable of incredible turns of speed in the milliseconds following the detection of a predator; if the hunter fails to take its prey straightaway its chances of a meal are minimal.

How are predators adapted for their diet?

One thing that most fish predators have in common is a large mouth, which can be opened rapidly to create considerable suction when the predator strikes. This suction draws the prey into the mouth at the last moment. In addition, predators usually have sharp, peglike teeth that point inwards; once caught in these teeth, there is little possibility of escape. Finally, fish predators usually have a large throat, allowing many of them to attack fish that are barely any smaller than themselves.

What tactics do the hunters use?

Open-water predators, such as jacks, use speed to overtake and then capture their prey, sometimes working in teams to corral their prey into tight groups or up against obstacles that block their escape. But most of the predators that actually live on the reef use some kind of stealth tactic. This might take the shape of camouflage, as used by ambush predators such as the scorpionfish and lizardfish. Scorpionfish and frogfish sometimes have small lures, formed by extensions of their dorsal fin, to entice smaller fish to inspect what looks like a tasty morsel. The curiosity that causes these fish to approach usually costs them their lives.

Another remarkable strategy is that of fish such as groupers and lionfish, which mingle — apparently innocently — with groups of prey fish until these lose their wariness of the predator and approach too closely, with fatal consequences.

Or they might stalk their prey, as trumpetfish and smaller jacks do. Trumpetfish are the absolute masters of this. They may conceal themselves within a school of harmless fish in order to get closer, or hide behind another fish, even to the extent of taking on its color, in order to try to convince their quarry that they are not there.

Other fish, especially sharks and moray eels, hunt under cover of darkness, looking for unwary or badly concealed resting fish.