Spectacular discoveries within coral reefs continue to be made and in recent years the Red Sea has proven to be a treasure trove for neuroethologists in particular. For those interested in animal cognition and the evolution of cooperative behavior, a rich and diverse list of predatory species – found to utilize complex cooperative-hunting techniques – as been growing. In 1989, Christophe and Hedwige Boesch categorized four distinct levels of cooperative hunting in chimpanzees in their American Journal of Physical Anthropology paper. Previously, scientists theorized that each of these four hunting categories varied from species to species and reflected a spectrum of innate cognitive abilities. As such, the highest level of complexity, collaborative hunting, where hunters each coordinate and execute quite different but complementary actions on the prey, was thought to be absent in ‘lower’ vertebrates.
Therefore, it was quite remarkable when Carine Strubin, Marc Steinegger and Redouan Bshary from the University of Neuchatel, Switzerland, recently found that a tropical fish species, the yellow saddle goatfish (Parupeneus cyclostomus), appears to form relatively stable hunting parties and actually employs sophisticated and highly coordinated actions. In their paper published in Ethology, the team describes versatile, cooperative-hunting techniques used by goatfish that were previously only attributed to ‘higher’ vertebrate species.
While snorkelling along the shallow coast line of the Red Sea, Bshary’s group reliably identified and tracked 17 adult individuals (based on coloration, size, and spot patterns on fins and body) for 3 months. Using digital photography, the team was able to distinguish individuals by the highly variable blue lines around the eyes and to analyse their behavior.
Observing the social behavior of the goatfish, Bshary’s team found the hunting system to be dynamic and flexible; some individuals spent time in stable groups, while another individual exhibited a primarily solitary existence. In addition, the team found that the social groups were not necessarily exclusive or permanent. Some fish switched membership from group to group but the researchers noted that the individuals found within groups were consistently similar in size to one another. The researchers also witnessed the goatfish working as a team, each assuming a specific responsibility in the hunt, either as a chaser or as a blocker. Remarkably, each individual goatfish exhibited flexibility in their role, acting as a chaser and directly pursuing prey during one hunt, while acting as a blocker on other occasions – strategically encircling the prey as it hid among corals.
Prior to this study, such multifaceted and dynamic team-hunting behaviors had been primarily observed in mammals and birds. Clearly we are just beginning to appreciate that ‘lower’ vertebrates are to be included in understanding the evolutionary process of collaborative hunting.