The Orca Pod-Cast explores the taxonomy and definition of Orca whales as a species.

In it, I discuss how I was inspired by a post I saw from Emma Luck, the Northern Naturalist on Instagram, and get into topics such orca ecotypes, and the recent recommendation to consider orca subspecies, Resident and Biggs, to be their own species.

Works Consulted.

Podcast Transcript:

Hello, my name is Emily.

I’m a senior undergrad in Wildlife Science, and today I’d like to talk about killer whales after seeing an Instagram post from a marine biologist named Emma Luck, username Northern Naturalist, that inspired me to read up on the proposal of two new killer whale species.

We’ve all heard of killer whales. Many of us probably saw Free Willy as kids. These iconic citations are actually in the Delphinidae family, classifying them as dolphins despite their common names containing, “whale.”

This is said to potentially be a result of a mistranslation of the Spanish name, “asesino de ballenas,” which means “whale killer” rather than “killer whale.” Keeping on theme, their genus name, Orcinus, is in reference to an Etruscan god of the underworld. They’ve also earned the nickname, “the Wolves of the Sea,” because of how they hunt as a group.

You might be wondering how such a charismatic species ends up with major taxonomic changes. I know that I personally often assume that because a species is popular or well known, it must be super extensively and thoroughly researched by now.

However, it turns out that’s not necessarily true, and with orca whales there are a lot of knowledge gaps on the species, actually. A lot of new species or reclassification of a species in the modern day comes from filling the knowledge gap on known organisms, rather than from undiscovered organisms.

Not that we don’t still discover new organisms, but they’re usually found in places humans have historically struggled to research because of physical restraints and technological limitations. So places like the deep sea or caves.

The definition of what makes something distinct enough to be a species seems pretty intuitive at first.

Like, you know, a bird and a dog are obviously different species, but how do we know that a dog is a different species from a wolf? Or that crows and Ravens aren’t the same species?

Reproductive isolation – Not being able to reproduce with species outside of your own species – is the most clear definition.

However, it isn’t the only definition and there are many exceptions to it. A species can be based on morphology, feeding habits, social behavior, and geographic location which are usually supported by genetics.

One of the more “out there” examples I can think of, is the time my evolution professor told us about a bird, whose name I can’t recall, that was delineated into a few species based solely on their unique songs, as the species would only reproduce with birds who use the same song as them, even though they were compatible with other birds.

And if I recall correctly, they weren’t significantly genetically different either.

But for the sake of this podcast, I’ll focus on the definitions provided from a paper that I cover later.

It defines a species as a separately evolving lineage composed of a population or collection of populations. And it defines subspecies as a population or collection of populations that appears to be a separately evolving lineage with discontinuities resulting from geography, ecological specialization, or other forces that restrict gene flow to the point that the population or collection of populations is diagnosably distinct.

So with that being said, let’s dive back into orcas. A lot of what we know about orcas varies depending on the specific population.

Orcas have a diverse range, being found in every ocean around the globe, so naturally there’s been variation observed based on region. Orca pods are also a tightly knit matriarchal community, so even different families in the same area can be pretty distinguishable from each other.

While all orca whales are considered understudied, so much so that the IUCN Red List feels that there is not enough data to assess the species risk of extinction.

Orcas, in particular in the southern hemisphere, are considered significantly less studied than other northern orcas because there isn’t really a lot of land mass in the southern hemisphere, so historically it’s been difficult to observe them in the open ocean.

Because of the extensive range of the killer whale, they have been broken down into ecotypes. However, as I was reading the literature, it sounds like most scientists are suggesting that the risk of oversimplifying these understudied individuals outweighs its usefulness.

The Northern Naturalist on Instagram cited a 2013 paper by Dee Brune et al. titled, “Killer Whale Ecotypes: Is there a global model?” This paper does a deep dive into the concept of ecotypes and critiques the concept.

As someone who didn’t know anything about ecotypes going into it, I found the paper very easy to understand and I felt like it gave me a pretty solid grasp on the concept while introducing their critique as well.

The ecotypes in the eastern North Pacific include the resident, offshore, and transient ecotypes.

Transient also being known as Biggs, named for the Canadian scientist Michael Bigg, and in the Southern Ocean it includes the ecotypes Type A, B, C, and D.

While the paper does describe a population in the North Atlantic, it doesn’t name them as the Type 1 and Type 2 ecotypes I’ve seen mentioned in a few articles.

One of my biggest takeaways is that a major thing that really makes a population of orcas unique is their hunting strategy that gets passed down through generations and is specialized to their prey of choice.

About a year ago now, the paper by Moran et al. titled, “Revised taxonomy of eastern North Pacific killer whales (Orcinus orca): Bigg’s and resident ecotypes deserve species status,” was published and this paper reviewed the data available on resident and Biggs ecotypes.

As the title suggests, they concluded that they deserve species level status. They focused on these ecotypes because they have the most extensive data available.

They used a combination of ecology, behaviour and morphology, and molecular genetics to support their findings.

The resident killer whale is named subspecies ater and Bigg’s killer whale is named subspecies rectipinnus.

Their names were actually given by Edward Drinker Cope way back in 1869.

The paper mentions that the common name of resident killer whale is a placeholder, while they hope to consult Indigenous people for a new common name, which I think is a really nice way to acknowledge the history Indigenous people have with the species, but also especially since their people are often overlooked in Western science.

The post I originally saw said that the two species proposed were accepted as subspecies, not species. And I reached out to Emma Luck on Instagram to ask if she could help explain who gets the authority to approve a new species.

I’m very grateful for her quick response that pointed me to the Taxonomy Committee of the Society of Marine Mammalogy.

They do an annual review of marine mammal species and subspecies, and it was in this that they explained the reasoning for classifying Biggs and resident ecotypes as a subspecies rather than the proposed species.

Their big concerns were about gene flow and a desire for a more comprehensive data on orca clades globally to understand just how distinct these groups are from other orcas. 

However, Emma Luck commented that this wasn’t the most popular decision and it might change in the future. 

I’m excited to see what taxonomic changes come from the Orca community in the future and I hope we are soon better able to research the southern populations.

It’s pretty crucial to have an understanding of these populations so that we can take steps towards the best management practices and assure that we don’t let more vulnerable populations suffer because they were lumped together with better off populations.

It’s also important to research the species now so that we can better understand how climate change is impacting them.

Thanks for listening and I hope you enjoyed learning more about the species as much as I did.