What happens to whales that die of natural aging, do they really drown? It's actually more frustrating than drowning

As we all know, mammals are a group of organisms that evolved on land, but in this group, there are some branches that do not satisfy land, that is, marine mammals, they choose to return to the ocean.

Of all the marine mammals, cetaceans (whales and dolphins) are the most adapted to the marine environment, having evolved to not need to return to shore to feed offspring like other marine mammals.

In fact, due to the relatively large size of cetaceans - blue whales are even considered to be the largest animals ever on earth, they are completely unable to return to land, and if they stay on land, they will be crushed to death by their own weight .

The reason why cetaceans are different from other marine mammals is that they are the first to enter marine mammals. About 50 million years ago, the ancestors of cetaceans set their sights on the ocean.

As another branch of marine mammals, pinnipeds (sea lions, seals, etc.), their ancestors went to the sea at least 20 million years later than cetaceans, so pinnipeds can still enjoy the sun on the beach.

In the ocean, cetaceans are mostly the top predators. They basically have no natural predators, especially whales. They are large and basically no predators are willing to take risks.

In fact, due to the lack of predators in the ocean, whales are very "defiant", they will not even avoid large moving objects such as ships, so about 20,000 whales are killed by ships every year, which is currently the main way of death for whales one.

However, because of the lack of natural predators, even though many whales have long lifespans, they are still more likely to live to natural death than other wild animals.

So what happens to those whales that are dying? Is it really going to be drowned as many say?

Whales still breathe with their lungs

Before discussing this issue, we have to briefly understand how whales breathe. As marine mammals, whales retain their original respiratory system. They do not use gills to absorb oxygen in water like fish, but use lungs to absorb oxygen in the air. of oxygen.

Many people may have wondered why whales that have lived in the ocean all their lives have not evolved gills?

It turns out that even in the water, the lungs are more advanced and more useful than the gills, and the reason whales are able to grow so big—so much bigger than the largest fish—is that they use their lungs to breathe.

A key factor that limits the size of animals is the oxygen content. This is because more energy is required to drive a larger body. The dissolved oxygen in seawater is very limited, about 4.59‰~8.72‰, but the air contains 21% oxygen .

Getting marine animals to breathe air is not an easy task, and whales have changed a lot for this.

First, the whale's esophagus and airway have been completely detached to avoid affecting the respiratory system when feeding underwater.

The part of the whales that we usually see that sprays water on their backs is equivalent to their noses, but it is a little different from what many people imagine. The water they spray is not actually swallowed when they eat, but flows into the respiratory tract when diving. , even though they seal their nostrils with their muscles, some water still gets in.

Second, whales have super high levels of hemoglobin and myoglobin.

Hemoglobin and myoglobin store oxygen in the blood and muscles, respectively. Higher levels mean they can store more oxygen at a time, which helps them dive into the water to prey.

Human blood is only about 30% hemoglobin, while whales can have more than 60% hemoglobin, so when whales breathe, most of their oxygen is absorbed, and most of the oxygen we inhale will be exhaled together.

These adaptive characteristics allow whales to have a strong ability to hold their breath. It is believed that the whales with the strongest breath hold can stay underwater for 2 hours on a single breath.

But animals that breathe with lungs, no matter how optimized their bodies are, they can't stay out of the water forever. Will those old and frail whales sink and drown themselves because they can't swim?

Do old whales really drown?

In fact, it's just an Internet myth that old whales can drown. No one has ever seen a whale drown without human intervention, and no stranded whale has been autopsied to reveal that the cause of death was drowned.

Whales do, however, drown, but some are juveniles because they are entangled in the lines of fishing nets or buoys.

The reason we think older whales drown is that they have to keep expending energy to get to the surface. In fact, adult whales don't need to swim too hard to stay afloat and breathe air. Some species of whales simply Floating and motionless sleep, just like some master swimmers can lie directly on the water to sleep.

The ones that really need to swim hard to surface are the newborn calves because they don't have much body fat and don't provide much buoyancy, so they sink without wiggling their tails for a while.

Because baby whales are not small, they have few natural predators in the ocean, but a lot of swimming can tire the baby whales, making them weak and vulnerable to infection or attack.

In general, even if whales need to breathe air, there is a high probability that elderly whales will not drown.

Like other top predators on land, the most likely cause of death for an elderly whale is that it fails to catch prey and then slowly loses power in starvation, at which point some whales are washed ashore (or stranded), In fact, many of the stranded dead whales did die of starvation, not suffocation.

What happens to a dead whale?

Now no one knows what happens to a whale in the final stages of its death because no one has ever seen it.

However, there are still many research teams who have seen abnormally dead whales, that is, after those accidentally stranded whales returned to the ocean, many of them did not survive.

The death process of a whale is probably like this:

When the whales lose power completely - probably not really dead at this point (I haven't been able to find research on whether whales are dead when they sink), they start to sink without any struggle.

The sinking cycle can last anywhere from a few hours to a few days, after which many whales float up due to the action of microorganisms that fill their bodies with gas.

From this point of view, the whales that have just died do not seem to attract too many other animals to eat them. Maybe in the cognition of many animals, whales are not inherently food.

After the whales re-floated, the first ones to move their mouths were all kinds of seabirds. They would settle directly on the whales and eat a few bites when they were hungry. At the same time, marine animals such as sharks would also come over to share a piece of the pie.

When the gas is expelled from the whale, the whale sinks again, a condition many people like to call a whale fall.

Not surprisingly, when a whale sinks completely to the bottom of the ocean, it becomes food for benthic creatures, but it is surprising that a single whale fall can support an entire ecosystem for decades.

Since sunlight can only penetrate about 200 meters into seawater, seafloor organisms beyond this depth cannot rely on the energy input of the sun as the support for the entire ecosystem like terrestrial organisms.

These creatures either build ecosystems based on hydrothermal vents, which are the main way of life under the sea, or on whale carcasses.

Marine researchers now know very little about the ecosystems created by whale fall, but it is certain that such ecosystems are also quite rich in species.

at last

The death of a whale is like the creation of a small universe, allowing many life forms to survive entirely on it for decades. But for whales, the whole process is still very frustrating.

In the process of sinking, floating, and sinking, the dead whales were eaten by marine creatures at all levels, which is a bit desolate to think about.

But then again, this may also be the best destination for life in nature!