To study the potential relationship between jaw morphology and the sharks’ life style, a quantitative analysis was conducted using X-ray computed tomographic scans of the jaws of 90 shark species and preparing 3D reconstructions to estimate how jaw shape of sharks evolved through time.
The results indicate surprisingly that among highly species-rich groups such as requiem sharks, the jaws display low shape variations. This is interesting since requiem sharks are one of the most widely distributed group of sharks. Another interesting finding is that most variable jaws were found among species living in the deep sea. “Although sharks from the deep sea are not as extensively represented in the data as reef sharks, they display the most disparate forms seen in our analysis,” explains first author Faviel A. López-Romero from the Department of Palaeontology at the University of Vienna.
Among many adaptations, sharks inhabiting the deep sea exhibit, in addition to bioluminescence various feeding strategies that range from taking big chunks out of whales to feeding on eggsor on cephalopods. For most of the species found in reefs and the large top predators in the open sea, the options seem more limited so that most mainly prey on fishes, and even other shark species. “Of course, many sharks in these environments feed on a large variety of prey with only few having adapted to a single, specific prey, such as the bonnethead shark, Sphyrna tiburo, which preys almost entirely on hard-shelled crabs, while shrimps and fish are only capture occasionally,” Jürgen Kriwet from the University of Vienna states, who was involved in this study.
