As we have covered before, a tiger shark will try to eat pretty much anything it can find, and because sharks can’t chew their food, a shark’s prey is either swallowed whole or bitten clean into large chunks and then swallowed.
What happens to all the little bones when a shark eats a fish? And when a shark is eating something bigger, like a seal, does it eat the bones too?
Sharks do eat bones. A shark’s powerful stomach acid can dissolve smaller bones like those in a fish. Others, like the bones of a mammal, may be regurgitated or digested, depending on the size.
Let’s take a look at how a shark can eat such hard food.
Shark Bite Force
The first step to eating – at least, when you’re a shark – is taking a massive bite.
Since we’re mostly wondering about larger bones, we’ll want to know how and if the big sharks can bite through bones.
Finding this out involves trying to measure the bite force of different shark species. And, as it turns out, this is hard!
Bite force will help or hinder an animal’s range of potential food items.
When you search online for shark bite force measurements, you’re going to get a lot of conflicting information. This is because different reports come out with different measurements – many of them inaccurate.
This is because there are different kinds of bites and different recording methods.
With sharks especially, researchers may only get one sample bite over the course of a long study, so it’s impossible to tell if the reading was correct and the measuring equipment functioned properly.
Also, different researchers use different hardware – if one is testing the bite force of a mako shark on an exposed bite plate and another is testing white sharks with a bite plate covered in rubber, it’s impossible to tell if the stronger bite was because of the species or the bite substrate.
Still, “we don’t know” isn’t a very satisfying answer for the internet, so here are some bite force estimates for known bone crunchers:
- Lion – 650lb
- Hyena – 1.1 tonnes
- White shark – up to 1.8 tonnes!
- Bull shark – 1.3 tonnes
- Tyrannosaurus – 3.6 tonnnes
But don’t get too attached to these figures.
You will find different numbers from different sources due to bad reporting and differences in measurement techniques!
So, can a shark bite through bone? Bull sharks and white sharks do seem to have a significantly stronger bite than a hyena, which is known to eat bones, so it’s very safe to say that, yes, sharks can bite through bone.
Now that we’ve cleared that up, what happens to the bone after it’s eaten?
Do Sharks Digest Bones?
A shark has some incredible specialization in its digestive system. Not only does it have a gut like a Tesla valve, but it’s also got some seriously strong hydrochloric acid and digestive enzymes to break down food as it travels slowly through the digestive tract.
Do sharks have enough power to digest bone?
In many cases, yes. Sharks have a system of slow digestion, and this means food passes slowly enough through that it’s heavily broken down and absorbed. Shark stomach acid is exceptionally strong at around a pH of 1.3.
So if bone sits inside a shark or long enough, it should dissolve.
Once it gets turned to mush inside the stomach, the wonders of the shark’s intestine come into play.
Shark intestines are particularly short! Even the great white has an intestine that’s only a couple of feet long.
This length reduction frees up space for an immense liver and compensates for its size through a series of spiral-like valves that slow the passage of food enough to extract as much nutrient value as possible.
Shark digestion can take an impressive 72h to complete – much longer than a human’s, and plenty of time to get the most out of their food.
If, however, there’s something a shark’s digestive system can’t handle, they have another solution:
Gastric eversion is a fancy way of saying ‘puking your guts out.’ Sharks literally turn their stomachs inside out and pass them through their mouths if necessary.
In lemon sharks, gastric eversion was seen removing indigestible matter from the stomach 16 to 17 hours after eating.
Puking like this helps clean the stomach of anything untoward that got swallowed during a period of over-indulgence. After turning it inside out, it is swallowed back up and returned to its normal position inside the shark.
How do Scientists Measure Shark Digestion?
Marine biologists always seem to be putting things into sharks. Tags, trackers, bite plates, cameras… the full list could make its own blog post.
To measure aquarium sharks’ digestion, they decided to stick with what they do best. Data loggers were inserted that sent a signal about the stomach pH over the course of a digestive cycle.
What they found using these loggers was a distinct change in acidity and in muscle contractions of the stomach when sharks feed.
Temperature records led them to design their optimal feeding patterns for captive sharks in the aquarium.
We can only assume there’s a lot more information to be found by putting things inside sharks.
Some of the larger, carnivorous sharks have some serious chompers.
They bite with enough force to easily cut through bone and have the digestive juices to dissolve it, too.
If at all they feel like it’s too much, they can always push their stomachs out of their mouths and rinse it off in the sea.