Can Whales Really Explode? - Let's Talk Science

WARNING: This resource contains graphic images and links to videos of deceased whales.

Have you ever noticed that some events seem to capture everyone’s attention? Stories of whales washing up on shore are among these.

Here’s an example, in April 2014, when nine blue whales were crushed to death in heavy ice off the western coast of Newfoundland and Labrador in April 2014. A few weeks later, a couple of them washed up on shore in neighbouring communities. Within a few days of being reported in the local media, this was a top news story around the world. Why? Because people were concerned about the future of this fascinating endangered species? Not entirely. People were mainly concerned that these whales might explode.

Why were they worried about this? Let’s look at the chemistry of a dead whale to find out.

Blue whales in danger

The majestic blue whale is the largest animal that has ever existed on Earth. It can be found in the open seas around the world - for now. At the end of the 19th century, there were 180 000 of them. But industrial whaling through the 20th century brought them and many other whale species to the edge of extinction. The International Whaling Commission banned commercial whaling in 1982. But by then there were few whales left to catch anyway. There are fewer than 250 blue whales in the North Atlantic now. There are 5 000 left overall. Given these numbers, you can imagine why the loss of the nine whales in 2014 was upsetting.

Can whales explode?

The idea is that as these huge mammals begin to rot, gases build up inside their bodies. Eventually, these gases might cause the bodies to explode, like an overinflated balloon would.

Did you know?

A blue whale's heart is about the size of a Volkswagen Beetle. The heart beats about 10 times a minute and pumps about 270 litres of blood with each beat.

But is there any scientific evidence supporting this fear?

Well, there is some basis for it.When animals die, their bodies begin to decompose (break down). This happens in two ways. First, the body's own enzymes begin to decompose it. This process is called autolysis. Meanwhile, bacteria decomposes the animal's internal organs and tissues, as well as any remaining food in their gut. This step is called putrefaction.

During the bloat stage of decomposition, gases like methane (CH4), hydrogen sulphide (H2S) and ammonia (NH3) are produced You may have heard of dead bodies having a pungent smell. That smell is produced at the bloating stage. It comes mainly from putrescine (1,4-Butanediamine) and cadaverine (1,5-pentanediamine). These chemicals are produced when amino acids in the body undergo decomposition reactions as part of autolysis.

Let’s look more closely at what is going on with these gases during the bloat stage.

Why are dead whales an “ideal” case of gas laws in action?

As early as the 18th century, scientists observed a relationship between the volume, temperature and pressure of gases inside a container.

Jacques Charles, a French physicist, noted in 1787 that heating a gas will cause it to expand and take up more space - in other words, have a greater volume. Charles’s Law states that for a given pressure of gas, the volume (V) will be proportional to the temperature (T).

V ∝ T

Charles’s law comes into play when a whale carcass is warmed in the sun. The increasing temperature causes the gases to expand and increase in volume. Unless these gases have somewhere to go, they will build up inside the dead animal, causing parts of the body to inflate.

Similarly, the volume of a gas is also proportional to that amount of molecules in that gas. This amount is measured in moles (n). This is Avogadro's Law, named for the Italian physicist Amedeo Avogadro. In 1811, he noted that if the temperature and pressure of a gas are kept constant, the volume and amount (moles) of that gas are directly proportional.

V ∝ n

Let's imagine that the whale carcass is lying on the shore for hours. The temperature remains consistent for several hours that day. As the bacteria break down tissue and put more and more molecules of gas into the carcass, the volume will increase.

Since the whale’s skin and blubber are so thick, the body can only inflate so much. Once it cannot inflate any more, it becomes more like a closed container. That is when Gay-Lussac’s Law kicks in.

Joseph Louis Gay-Lussac was a French chemist and physicist. In 1808, he noted that if you keep the volume of a gas constant (such as in a closed container) and you apply heat, the pressure (P) of the gas will increase. Mathematically, you can say that pressure is proportional to temperature (when volume is kept constant).

P ∝ T

So, when the temperature goes up but the volume does not, the pressure goes up. Eventually, if the pressure inside a container gets too high, it can cause the container to break and release the built-up gases instantly. In other words, this can cause it to explode.

Did you know?

An explosion is a rapid expansion of a gas. It is the impact of the shock waves that cause the damage.

Do whales often explode?

Such extreme cases of exploding whales are few and far between. Most scientists agree that whale explosions are unlikely. That’s because a dead whale’s skin will gradually form small tears, which will release some of the built-up gas. Whale explosions are more likely to happen if humans interfere with the corpse. For example, the skin could be punctured by an object. The skin might also break at a weak spot if someone walks on the carcass.

So, if you come upon a dead whale rotting on a beach, you might want to consider staying away. The smell is very persistent (long-lasting)! In a 2001 case of a dead beached whale, people removed the meat. Scientists reported that some tools used to remove the meat still reeked of whale 10 years after the job was done. The danger of a whale explosion may be slim. But you certainly would not want to risk getting sprayed by rotten, liquid tissues!

Did you know?

In 2017 the Royal Ontario Museum (ROM) in Toronto opened an exhibit of the reassembled skeleton of one of the whale carcasses that washed up on the Newfoundland shores in 2014. The exhibit makes use of the skeleton as part of an education program to help people understand a bit more about the world’s largest, and most mysterious, animals.