The experts realized that what they were looking at was a set of gray whale twins that were conjoined. That is to say, as the twins had developed in their mother’s womb, the fetuses had fused together, in this case, at the stomach. Whether they had been still-born or had died soon after birth remains a mystery. It is also unknown if the mother survived the birth.
Interestingly, the database of the Natural History Museum of Los Angeles County didn’t turn up any other cases of conjoined gray whale young. However, such twins have been recorded in sei, minke and humpback whales. Jim Dines, the collections manager at the museum, told National Geographic that “because of their reproductive biology, whales and dolphins almost always have a single baby.”
Dines also added, “In the case of twins, the mother has to provide nourishment for two growing fetuses. And that may result in two slightly smaller fetuses rather than one normal-sized one. These were pretty sizeable. There’s a fair chance the mother was trying to deliver them and couldn’t.” Given the extreme rarity of conjoined whales, then, it’s unsurprising that scientists are unable to come to firm conclusions.