Ancient whales were predators not gentle giants | Hacker News Reader

Ancient whales were predators not gentle giants

phys.org

92 pointsdnetesn42 comments

Here's the paper link (kudos to the journalists for at least giving us the title of the paper, if not a link we could follow; sometimes the article in the popular press looks nothing like what the scientists published). http://rsbl.royalsocietypublishing.org/content/roybiolett/13...

If I read this correctly, the discovery is not that the early whales were predators, but that filter-feeding evolved separately from their teeth; that is, the baleen - which is not homologous to teeth - is the first filter mechanism that the whales acquired, while previously, some people thought that the whales developed filter-feeding with their teeth before developing the baleen.

This is an exciting discovery, I suppose, for scientists studying whale evolution, but probably for nobody else. The popular press treatment turned it into "they discovered that whales were predators", which makes little sense, since a) everybody knew the whales did not have baleen when they were land-dwelling, I mean, how would that work; and b) all whales obviously had teeth at some point in their evolution, before the baleen whales lost them.

This also greatly simplifies thier evolution. If the teeth were used as a filter then they would have likely evolved into a better filter rather than a new structure developing. Ive never heard of such parralel development of different structures to acomplish the same task. One normally becomes dominant and that's the path. The eventual loss of unneeded teeth and the later development of baleen seems much easier.

> Ive never heard of such parralel development of different structures to acomplish the same task.

https://en.wikipedia.org/wiki/Queensland_lungfish#Breathing

The linked article discusses the lung fish which has gills for getting oxygen from water and a lung that can be used to extract oxygen from the air. It seems that this is an example of different structures used for the same purpose, extracting oxygen from the environment, but not the same task. One task extracts oxygen from water and the other from air.

That just introduces more questions. What was the evolutionary advantage of baleen before it was used for filter feeding?

Edit: Three hypothesis outlined in the parent's linked PDF:

* Archaic mysticetes used their denticulate teeth to (suction) filter feed like living leopard and crabeater seals, thereby linking tooth function directly with the evolution of bulk feeding and baleen.

* A period of overlap, during which baleen and teeth would have functioned alongside each other.

* Archaic whales first turned from raptorial into suction feeders, which then triggered tooth loss and, eventually, facilitated the emergence of baleen.

The article also talks about "killer whales" and their teeth, but Orcas aren't whales. They're dolphins (or more specifically, they belong to the porpoise group of mammals).

While Orcas are members of dolphin family (Delphinidae), they are not members of the porpoise family (Phocoenidae) and the whole Orcas are not whales distinction is kind of silly anyway because they're all cetaceans.

Dolphins, whales, orcas, and porpoises all share a common ancestor before getting back to land animals, they are all cetaceans.

> everybody knew the whales did not have baleen when they were land-dwelling, I mean, how would that work

And what if everybody were wrong? Perhaps some quirk led to development of baleen, which the proto-whales discovered was useful in the sea. So they stayed there.

Then we would expect all whales to be baleen whales, but they aren't. The fact that only one branch of cetaceans has baleen suggests that it came about after the cetaceans' common ancestor went in the water.

I see, thanks. I think that the type of classification that you are referring to is called Cladistics.

And modern sperm whales hunt giant squid. They have found giant squid beaks in the stomachs of sperm whales. And the whales will have scars from the battles. But it happens at such depths that it hasn't been seen, to my knowledge.

edit: whale, with calf, eating a giant squid: http://news.nationalgeographic.com/news/2009/10/photogalleri...

Those images are spectacular. Thank you!

And?

I don't understand what the logical connection is to the article. Sperms whales are not the only example of odontocetes (toothed whales). Orcas hunt seals, bottlenose dolphins hunt fish...

A Blue whale can consume as many as 40 million krill per day, if that's not a predator, not sure what one is.

A single death is a tragedy; a million deaths is a statistic.

A billion just a foot note?

Do you want to write a song for the dead krills? Go ahead, write one.

On a more serious, less timely paraphrase, the shear amount of death at the bottom of the food chain both on land and at sea is mind boggling.

Yup, all food is death. Vegetarians and vegans are just picking their ethical battles, really.

I sometimes idly wonder things like how far we are from sci-fi synthesis of a complete diet from entirely inorganic materials that have never been in a living thing. It might even become a necessity as a spacefaring species. Although, humans separated by interstellar distances would almost certainly diverge to the point where maintaining a single “species” becomes dubious, even if you had constant interbreeding, so you might have humans eating local plants & animals on other planets that are nutritionally useless or hazardous to Earthlings.

They certainly evolved from rather toothy predators as well.

For anybody in Toronto I highly recommend the Blue Wale exhibit at the ROM! They have an entire skeleton and it is humbling and awesome. If you're able to go, then go before it ends here. I think it's touring after it finishes up there.

https://www.rom.on.ca/en/blue-whale

edit: Adding more info --

* Photos from the excavation of the carcass https://www.rom.on.ca/en/collections-research/research-commu...

* Photo of the skeleton and vague tour plans https://www.thestar.com/news/canada/2017/08/29/roms-blue-wha...

* Video from the exhibit, including the skeleton https://www.rom.on.ca/en/learn/activities/at-rom/bluewhale

* Photo essay and back story http://projects.thestar.com/rom-blue-whale/

Didn't we know that already?

I mean, the evolution of Cetacea is fairly well understood by now. We know they all derive from a terrestrial small carnivorous artiodactyle. And all descendants had sharp teeth until relatively recently. Even today quite many of them are still active predators.

1. https://en.wikipedia.org/wiki/Evolution_of_cetaceans

Yes, cetacean evolution is one of the most well-studied areas, with decades of research behind it.

This particular finding seems to be about early baleen whales, back when they still had teeth (not just baleen). Seems like early baleen wales had very sharp teeth that were likely used for cutting, not for some sort of early type of filtration.

You might be interested in the actual paper: http://rsbl.royalsocietypublishing.org/content/13/8/20170348

Whether or not something is a predator is a lot more important to us than to biology. The distinction between eating small krill and eating large fish, even less so.

Lots of mammals seem to evolve back and forward between various food sources. Look at our branch. Most/many primates have a mixed diet, in many of the families. There are some specialists like gorillas and bleeding heart baboons, and they’re not necessarily related.

So, our ancestors were probably all over the predator-prey spectrum.

Not to mention, krill are animals. Only at the scale of a whale could filter feeding be considered gentle giant behaviour. At our scale it's probably more like genocidal giant if you consider the thousands of little animals which dissolve alive inside the whale.

It's not so much what whales eat that matters, rather than how they eat it. The size difference between a whale and a krill is so big that for all intents and purposes, whales feed much more like a cow than a lion. They're browsing, except they don't browse vegetals, but small animals.

To say they are not predators makes sense in the behavioral sense.

They do actually hunt for denser populations of krill. So, IMO it's closer to predator behavior than pure browsing.

Cows also seek out denser grass, so that hardly destroys the analogy.

Another angle to look at it might be how much the prey try to avoid being eaten. I know nothing about Krill, but if they have any navigation control and/or instincts, I imagine that differs greatly from cows.

Granted, I've never observed grass to see if it avoids cows either. /shrug

Many plants do have defensive measures to ward off herbivores. For example, when grass is damaged it releases numerous chemical signals into the air. This is what causes the freshly-mown lawn smell: http://mentalfloss.com/article/30573/what-causes-fresh-cut-g...

These defensive measures have a huge range. Some might only increase healing, others might attract life higher up in the food chain to attack the herbivores, and still others might be able to actively damage the herbivore.

My point is that eating plants may be less passive than we think. All of life has had billions of years to evolve, so the interactions can be pretty sophisticated all around.

Bubble netting is a little more complex than just walking to a new area. https://en.wikipedia.org/wiki/Bubble_net_feeding

Also, baleen whales are not limited to krill and do eat a lot of larger fish.

They are not browsing, they actively hunt game, corral them, and eat them. They are quite literally predators in the behavioral sense.

This is illustrated nicely on the BBC series "The Hunt". Not only to they corral but they work with other fish in this process. There's a great scene where a Blur Whale comes out of the corner opening it's mouth and just swallows a massive gathering of krill. Highly recommended!

Just to be clear - when I eat Jell-o I use my toungue to force it out between my teeth and pretend I'm a whale.

Am I in danger of developing baleen?

When I visited the whales exhibit at the Museum of Natural History in New York, 3 years ago or so, they showed that early whales were kind of like alligators, so I'm not sure why this is a new discovery. Perhaps it just firms up the timeline for when their feeding mechanism changed, or maybe there's some other detail that's escaping me here.

Just to add a little to the discussion, after reading the article I was curious to know and understand what the ancient land-dwelling ancestors to modern day whales looked like, and found this:

http://evolution.berkeley.edu/evolibrary/article/evograms_03

It's very fascinating and clearly shows the evolution of whales in great detail; apparently whales and hippos are related, but are two branches from a common ancestor (which I took from this that we don't yet know what ancestor?).

Regardless, after looking at that page, I clicked around the site - and found the whole thing really intriguing and detailed.

All whales are predators. And there are plenty that still have teeth and are rather ruthless hunters (sperm whales, orcas, etc...).

Hey, you don't suppose multiple competitive threads of evolution were occuring at the same time do you?

Curious choice of words. Are we too predators or gentle giants (from smaller animals' perspective)?

It's just a dumb headline. All whales are predators. Some just evolved to filter crustaceans out of the water intead of tearing flesh off off fish. Krill are still animals. Gray whales are still carnivores.

But yes: early whales had a lifestyle that looked more like a dolphin's than a humpback's, which isn't surprising since a humpback skull works very poorly for hunting animals on land, which is where their common ancestor came from.

What's actually more interesting is that the only other living descendant of that common ancestor isn't a predator at all, nor does it look like one. It's the Hippo.

Gray whales and sperm whales are carnivores.

So are Humpback whales, which switch off between krill and small fish (like sardines), depending on what's available.

Also, hippos have been observed killing and eating other animals, so they've been moved into the "mostly herbivorous but enjoy a meaty snack on occasion" category.

They are still predators, they just pivoted to a different diet.

I guess when you become so large you don't have any direct predator you have options. Monopolistic Whales.

Wow, fascinating! Wondering what happened, that such a huge predator stopped hunting - convenience, and that's why their teeth fell out? His skull looks like a dragon skull from Game of Thrones though...

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