Adaptive Value

Increased Success

According to Bshary's article “Interspecific Communicative and Coordinated Hunting between Groupers and Giant Moray Eels in the Red Sea,” cooperative hunting benefits both groupers and giant moray eels by increasing their hunting success (Bshary et al. 2006).


Experiments involving coral reefs have shown that prey animals such as P. moluccensis have developed diel foraging patterns (they perform most foraging activities during the day and decrease this behavior at dusk) in response to nocturnal predators. Thus, giant morays largely benefit from this cooperative relationship by having access to prey which are normally only active during the day (Bosiger and Mccormick 2014).

The success of the relationship between morays and groupers relies on the different hunting strategies that each fish has developed. Since groupers hunt in open water and morays hunt in closed-spaces, they leave their prey with little options as to where to swim and experience greater hunting success when cooperating. Along with increased rewards, groupers and giant moray eels have an advantage over other cooperating animals: they swallow their prey whole. Without the opportunity to fight over a carcass as is the case in many mammals, cooperative hunting becomes a less costly and hostile practice. Thus, both participants in cooperative hunting enjoy increased rewards as well as a decreased risk. Although both fish benefit, giant morays have a greater advantage in the relationship because they are nocturnal and will typically be inactive when groupers are hunting. Having a grouper signal the presence of nearby prey during the day time, significantly increases the hunting success of moray eels during that time. (Vail, 2014)

Figure 8. Photograph of trout and giant moray eel cooperative hunting

Why Cooperate?

Figure 9. Image of prisoner's dilemma (Dugatkin, 2002)

Cooperative behavior in animals is often explained through theories of kinship. Relatedness or kinship theories state that an animal will execute an altruistic behavior (a behavior that may decrease its lifetime reproductive fitness) only if it benefits a closely related animal. However, giant moray eel and grouper cooperative hunting is an interspecific behavior and cannot be explained by kinship theory. The prisoner's dilemma (Figure 9) or the concept of two individuals choosing to cooperate over defecting because of a greater chance of reward when both individuals cooperate can be used to explain the collaborative hunting behavior of giant morays and groupers (Dugatkin 2002). In this case, both species experience a greater reward when hunting cooperatively than individually, driving both morays and groupers toward cooperation.