2024-01-29 15:11:45
He was the star of Stephen Spielberg’s “Jaws” from 1975 and even lent his name to the German title of that film: Jaws Carcharodon carcharias, also called man shark. For its diet it prefers to bite squid and bony fish, including tuna, rather than surfers or divers, but the species is actually the largest of the sharks that use teeth and the largest predatory fish in the geological present.
Despite its media prominence, the great white shark – which is capitalized because it is only white on the underside – has not yet been fully researched in some aspects. In particular, not much is known about its mating behavior, and so far its babies have only been able to be studied using embryos in killed mothers. Live great white shark newborns have never been observed.
Until July 9, 2023. On this day, nature filmmaker Carlos Gauna and Philip Sternes, a doctoral student in biology at the University of California at Riverside, circled a drone over the Pacific off the California coast not far from Santa Barbara. Suddenly something strange appeared on the control screen: a great white shark about one and a half meters long, which was actually completely white. “We turned up the magnification, switched to slow motion and saw that the white coating was peeling off the body as it swam,” remembers Sternes. “I think it was a newly born great white shark that shed its embryonic outer layer.”
Egg feast in the womb
The observations have now been published in an article in the specialist journal Environmental Biology of Fishes documented and classified. The authors also discuss the possibility that the peeled off white tissue could have been a pathological formation. It is more likely to have been formed by a milky uterine secretion that the shark mothers secrete on the inside of their two uteri and that serves as food for the unborn shark babies.
Because how many shark species is Carcharodon carcharias viviparous: The females, which can be more than five meters long, do not lay their eggs; rather, the brood hatches in the womb – up to 14 at a time have been encountered – and then feasts on unfertilized eggs and the uterine secretion. In sand tiger sharks (Carcharias taurus), however, intrauterine cannibalism was observed. Here only one embryo experiences birth in each uterus.
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Another reason to believe that the observed juvenile had just been born is Carlos Gauna’s observations of pregnant female great white sharks in the waters off Santa Barbara in previous years and in the weeks before July 9, 2023. ” In the days before, I filmed three large, probably pregnant females,” explains Gauna. “It doesn’t take much imagination to explain where the baby came from.”
Thirdly, the biologist Sternes recognized the typical body characteristics of a fresh young animal in the specimen that was then filmed. “In my opinion it was only a few hours old, a day at most.” The observation is also scientifically interesting because it provides, for the first time, evidence of where white sharks prefer to give birth to their young: relatively close to the coast , in this case about 330 meters from the beach. Quite a few scientists had suspected that this was happening further out at sea. This is also important for efforts to preserve this species. Because almost fifty years after “Jaws,” the great white shark is an endangered species.
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