Learning From Others
For most of their lives, coral reef fishes live in close contact with hundreds or even thousands of other reef dwellers. There are disadvantages to this in terms of shortages of space for territories and high levels of competition for food. But there is some compensation for the fish in the way that information is quickly transmitted across the reef. Reef fishes are particularly sensitive to the signals and the behavior of others, allowing them to learn a host of things quickly, from the location of food to the presence of predators. Sometimes that information is intended to be broadcast, at other times it is picked up by eavesdroppers -- there are few secrets on a coral reef.
Where do fish get their information?
All animals have their own private information, based on their own learning, exploration and experience. But gaining private information takes energy and time; to learn everything about its habitat a fish would
have to investigate huge areas of reef for itself, which would not only take time but would expose that fish to considerable danger. As a result fish often obtain their information from watching the behavior of others. This so-called public information is less reliable than finding things out for yourself, but it is much easier.
For example, the sounds that fish make when feeding are known to attract fish from all over the reef to investigate. In a different context, if just a few fish perform a sudden fright maneuver, such as a dash towards the reef, this can cause others nearby to respond by copying them.
Can fish learn from other fish?
There is plenty of evidence to show that fish can, and do, learn from one another, a process known as social learning. There are several examples of fish watching a conspecific eating a completely novel food item and then imitating the behavior by trying the food itself.
Triggerfish, such as the yellow-spotted trigger (Pseudobalistes fuscus) and the orange-lined trigger (Balistapus undulatus), are among the smartest fish, with several tricks that help them deal with well-defended prey, such as sea urchins. Individual orange-lined triggers in the Red Sea have been seen carefully biting off some of the spines of sea urchins before picking them up and carrying them to the water surface, then dropping them and feeding on the unprotected underside of the urchins. This behavior is not known in other parts of the world and it seems likely that this successful innovation by an individual triggerfish has been learned by a small group of triggers.
Do fish have traditions?
Simply put, traditions are behavior patterns that persist in populations between generations. One such tradition is seen in the migration patterns of many reef fishes between their daytime and night-time ranges. Many surgeonfish do this, but the most compelling evidence comes from a study on French grunts. When some fish were moved between different populations, they fell into step with their new associates and followed their exact migration paths, at first simply copying and later learning them. However, just because a particular resting or feeding place has been used for generations, it does not necessarily mean that it is the best one -- it is tradition that keeps the fish coming back. Tests on the mating sites chosen by blueheaded wrasses showed that when two populations were switched, each going to the other's former range, the incomers chose totally different spawning sites to those used by the previous occupants, but once chosen, these new sites were maintained by the population year after year.