What would happen if you were swallowed by a whale?

At the Naked Scientists we get sent a lot of interesting questions. This one came in from Joanne and David from Dublin, and certainly got us all thinking:

If a scuba diver was accidentally swallowed by a toothed whale, such as an orca, whether he could escape back up the oesophagus? Would they be crushed by the oesophagus muscles? Could the whale regurgitate the diver back up? Would he be dissolved in the whales digestive enzymes, and if so, how long would it take to corrode the wet suit?

Professor Joy Reidenberg, an animal anatomist, knows a thing or two about whales, and took us through what might have happened to the Biblical Jonah...

What is a toothed whale?

First, I'd like to address what a toothed whale is. Toothed whales, or as scientists call them: odontocetes, are the subset of whales that possess teeth instead of the baleen plates of filter-feeding whales like humpback and blue whales. Toothed whales include the very large sperm whale, beaked whales, pygmy and dwarf sperm whales, but also dolphins and porpoises. Orcas, also known as killer whales, are in the dolphin family. Many other medium sized toothed whales with the word "whale" as part of their name are really just big dolphins, including false killer whales, beluga whales, pilot whales, and narwhals.

Could a whale swallow a person?

Out of these dolphins, orca shave the biggest mouth. However, an orca's gape is probably only big enough to engulf a human's head, but not much more of the human's body. A further restriction is the opening of the throat that is much smaller than the gape of the mouth. The throat is able to accommodate a large, whole salmon - perhaps about the size of a human thigh. Even the sperm whale has a relatively small throat opening, despite the wide gape of the lower jaw away from the rest of the head. So, an orca accidentally swallowing a human, especially one sporting a scuba tank, is akin to saying you accidentally swallowed a watermelon - WHOLE! It's physically impossible.

Now, let's talk about the likelihood of an orca, or any other toothed whale, actually consuming a human. To date, there are no records that I could find of an orca, sperm whale, or other toothed whale consuming a human. However, there are some cases where orcas have attacked and even killed humans, but they did not consume them. It is thought that frustration, surprise, fear, dominance, and a range of other factors unrelated to hunger may underlie this behavior. Of course, one can say the same thing about pet dogs. They can attack and even kill humans, but they do not tend to eat us as we are not their usual prey item.

For the sake of this discussion, let's assume the orca did want to consume a human. It would have to be a purposeful act, as humans are just too large to be accidentally swallowed. In that case, the humans would have to be torn into smaller pieces in order to fit down the throat.

Could they escape back up the throat?

Dismembered pieces of a human are unlikely to crawl up the oesophagus, or swallowing tube! However, for the sake of this discussion, let's assume a live, intact human were miraculously placed in the oesophagus. That human might squirm, but would find it difficult to have enough maneuvering room to move arms and legs to crawl. The arms would likely be either flattened against the body. However, if they were extended above the head, then the elbows would not be able to bend very much. Maybe pushing laterally in both directions could stabilize the person's position to not be easily swallowed further. Also, consider that there are no easily grab-able surfaces to clutch, so pulling the body up would be a difficult feat. It's not like grabbing the hard projections of a rock-climbing wall. Imagine trying to crawl in a tight-fitting sleeping bag made of wet, slimy, foam-rubber. If you have long fingernails, you might be able to use them like claws to get a better grip. Let's add another layer of complexity to this scenario: orcas and other dolphins always swallow whole prey head-first. If they swallowed a fish tail first, the spines on the fish's back would get caught poking into the oesophagus. Head-first ensures the spines are flattened out and pointed away from the direction of swallowing. So, if an orca could swallow a human, it would likely be head-first. That would make it awfully hard to crawl out too. Of course, I still want to caution you about taking this scenario seriously. The orca's throat is very short, as they have practically no neck. Therefore, even if a human could fit into its narrow lumen, the feet would be still sticking out of the mouth when the head entered the stomach. If it were me, I'd try to open the scuba tank valve and let the force of compressed air act like a jet propulsion rocket to propel me backward out of the throat.... Assuming I could even reach the tank valve while stuck in the tight-fitting oesophagus!

Would they be crushed by the oesophagus muscles?

Dismembered pieces of a human are unlikely to be able to withstand the propulsive effect of the sequential constrictions (peristalsis) of oesophagus muscles! However, I doubt the constrictive power of the oesophagus is enough to crush a whole, live person. The muscular layer of the oesophagus is not that thick. For that kind of power, the muscles would have to be more in the league of those of a very large constrictor snake's body, such as a python. I'd worry much more about the crushing force of the orca's jaw, as those teeth penetrate, and the power of the whale's swimming musculature that, when suddenly contracted, move the whale forward with such force that the bitten area grasped in the mouth would be torn off of the body!

Could the whale regurgitate the diver back up?

There is very little information on whale regurgitation. Herbivore ruminants, such as cattle and sheep, regurgitate and chew their cud. Whales, however, are carnivores and so do not ruminate. Given that whales evolved from an ancestor related to modern ruminants, it is conceivable that they might have the capacity for regurgitating. However, as they cannot chew (their teeth are only used for grasping, not grinding), rumination is unlikely. Perhaps vomiting is more likely (regurgitation is probably a misnomer as it implies normal function). This would occur if the contents in the stomach were undesirable (such as food poisoning). I had heard of "willful" vomiting in a captive dolphin. It is unclear why it did this, but it may relate to boredom, and thus a bizarre way to provide self-entertainment. Regurgitation might occur in sperm whales, helping them get rid of pointy squid beaks - like a cat expelling a hairball. If the beaks are not vomited up from the stomach, then they become covered in a waxy mass of ambergris that is produced in the intestinal tract and eventually discharged from the other end. It is unlikely that sperm whales can vomit a solid chunk of ambergris from the intestines. There is no record of orcas vomiting solid remains from their prey. I suspect it would be unlikely that they would vomit up the remains from a scuba diver. More often, I have seen beached whales that died because they could not vomit up something that they should not have eaten, like plastic. Plastic bags floating in the water look like squid, and are very appealing to some toothed whales. These bags will get stuck in their digestive tract because they can't dissolve it. Unfortunately, the bags can block the digestive tract, causing the whale to slowly die of starvation.

Would he be dissolved in the whales digestive enzymes...

The digestive enzymes of a carnivore that can eat other marine mammals can surely digest pieces of a human's flesh too. The problem isn't the digestion process. The problem is the mechanics of the size constraints of fitting a whole human into an orca's digestive tract. Of course the scuba gear presents a bigger problem.

How long would it take to corrode the wet suit?

A scuba diver's neoprene wetsuit is an artificial rubber that is essentially type of plastic, made of polymerized chloroprene. Similar materials are used to make protective, oil-resistant and acid-resistant gloves, and therefore is unlikely to be digested by stomach enzymes. Commercial recycling programs can essentially melt neoprene with heat and chemicals that render it soft so it can be reclaimed and remolded, but it doesn't appear that these processes can dissolve the neoprene. If these harsh treatments can't dissolve it, then it is likely that stomach acids can't either. I would worry just as much about the other scuba gear too, like the compressed gas tank, rubber hoses, gauges, and lead weight belts. All of these items would likely make the whale very sick indeed! If the whale can't digest it, then it will try to pass the items out. However, these bulky items are likely to block the intestinal tract and cause death.