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The Case of the Mystery Whale

A Bryde's whale catches a meal
The three ridges on the top of this Bryde's whale distinguishes it from the sei whale, which only has one. (Jason Thompson, Flickr)

In 1871, John Anderson, then curator of the Indian Museum of Calcutta, caught wind of a beached whale along the coast of Burma (now Myanmar) from a newspaper article. The whale became trapped up a small creek and was said to “have roared like an elephant and so loud as to be heard a very long way off.” Wanting the skeleton, Anderson persuaded the Chief Commissioner of British Burma, Ashley Eden, to send a deputy to retrieve as many bones as possible. Anderson was sent a skull, nearly all the vertebrae backbones, a bit of one flipper, and some baleen. After carefully examining the bones he determined it a new species Balaenoptera edeni, or Eden’s whale after the Commissioner. 

Then in 1912, Orjan Olson described a similar whale off the coast of South Africa. A Norwegian whaler, he was most interested in the external characteristics of the whale and wrote about his new Bryde’s whale (pronounced "broodus") in a newspaper article back home. With a body like a sei whale, it had an extra ridge running along the center of its head, giving it a subtly unique appearance. There was one problem—Olson never described the skeleton, a necessity when describing a new species. But the name Bryde’s stuck, and when whalers began to see the baleen whale with three ridges on its head, that is what it was called.

By the early 20th century, scientists began to have doubts that the two whales were different. In 1950, scientist George Junge compared newly discovered skeletons of Bryde’s whales from South Africa and Singapore to skeletons of Eden’s whales stored in several museums and proclaimed that despite small differences they were the same species. Case closed—the Bryde’s whale and Eden’s whale were the same and would be called Balaenoptera edeni (though its common name continued as the Bryde’s whale).  

Not quite. Determining a species requires more information than just physical appearance and the bone record. Through further study, scientists revealed that there are significant geographic differences between the two. Bryde’s whales (currently the subspecies Balaenoptera edeni brydei) live in tropical waters across the globe while Eden’s whales (currently the subspecies Balaenoptera edeni edeni) only live along the coast in Indo-Pacific waters. There is also a size difference—Bryde’s whales can reach 49 feet (15 meters) in length, while Eden’s whales are slightly smaller, only reaching 38 feet (11.5 meters) long. 

“Putting the pieces together over the last one hundred years has been challenging,” said Matt Leslie, a whale biologist at Swarthmore College currently studying Bryde’s whales. “Subsequent researchers tried to continue to research the whales but couldn’t tell if they were looking at a Bryde’s whale or an Eden’s whale. Even today there are publications that are like ‘I think they were looking at a Bryde’s whale, but I’m not quite sure.’” 

Now, with the help of genetic testing, scientists hope to clear up the confusion once and for all. Currently, scientists are piecing together genetic clues about both the Bryde’s whale and the Eden’s whale to see if they are the same species. Preliminary research shows that though the two live in the same area, they are, in fact, genetically unique. This means that the two whales are not breeding with one another, strong evidence that they are actually two separate species.

a Bryde's whale surfaces
A Bryde's whale (Balaenoptera edeni) takes a quick breath at the sea surface. (NOAA)

What’s more, there may even be a third whale masquerading as a Bryde’s whale. Genetic studies of Bryde’s whales in the Gulf of Mexico indicate that they too have a unique genetic makeup that sets them apart from other Bryde’s whales. For now, scientists have labeled them as their own subspecies and are awaiting further confirmation from more rigorous tests. Since there are less than 100 individuals in the gulf, a concerted effort is underway to figure out if indeed they are unique and in need of protection. As learned from the confusion over a hundred years ago, having a reference skeleton or type specimen is key. In October 2019, the Smithsonian National Museum of Natural History acquired a skeleton of a Gulf of Mexico Bryde’s whale that was found dead in the Florida Everglades. The hope is that should new data confirm that this whale is unique, there will already be a reference skeleton ready for study.   

“It’s crazy that in our own backyard in the Gulf of Mexico, right offshore, we have this whale that’s huge,” said Leslie. “It’s a full 35 foot whale and we don’t know what it does or how it makes a living. We can’t even scratch the surface on the first question of ‘What the heck is this thing?’” 

This effort may seem like splitting hairs. Why does it even matter whether we recognize the Bryde’s whale and Eden’s whale as two or even three unique species? (Not to mention the other species that are similar and can be confused by observers—the sei and Omura’s whales). An animal gains protection through environmental legislation which requires accurate naming. In other words, protection is given to species that are in danger of extinction. But we have to know where one species stops and the other begins, otherwise a unique species doesn’t get the individualized protection it needs, and may go extinct. If we are to assume that both Bryde’s whales and Eden’s whales are the same species, a threat that affects one group more than the other would be devastating. Although whaling isn’t as much of a threat today, whales face a world of increased pollution, fishing, habitat destruction, and immense shipping traffic— death by a thousand cuts. 

For example, Bryde’s whales spend the majority of their time offshore, making them more likely to come face to face with speeding ships—ships near shore must slow down, which gives coastal whales, like Eden’s whales, more time to duck out of the way. Ship strikes can be fatal for whales and could potentially hurt whale populations that swim near them for most of their life. If the overall health of all Bryde’s whales (B. edeni edeni and B. edeni brydei) is assessed based upon every single whale, the shipping threat that only hurts the select few coastal individuals may not be deemed significant enough to warrant protection for the entire species.  But if Bryde’s whales and Eden’s whales were viewed as separate species, the shipping threat would now affect the majority of the offshore Bryde’s whale species (B. edeni brydei) and specific action could be taken to protect those whales.

The story of the Bryde’s and Eden’s whales also reveals just how little we know about life in the ocean. If a giant whale the size of a school bus can spark so much debate, just imagine what else we are missing. 

October 2019