Tigers don't eat their cubs, but why do these 5 species?

You may have heard of cannibalism in the animal kingdom. For example, female praying mantises will bite off the heads of their mates, and devour them immediately after mating.

The same thing happens with black widow spiders . They get their name because widow spiders also eat their mates. Soon after becoming a wife, they turn into a widow themselves.

Other animals have been caught cannibalizing their own siblings. In the purple toad, for example, tadpoles that mature early can eat their younger siblings.

In sharks , fratricide occurs even earlier, in the womb. The stronger embryos cannibalize the weaker ones, so that they are born with the greatest survival advantage.

But among these cruel acts, there is one that seems even more cruel, and almost unforgivable. Some animals have been caught red-handed - eating their own offspring.

When there is a folk saying "A tiger does not eat its own cubs" , these animals do such a terrible thing. But why do they have to do that? Let's see what their answer is:

"If someone is going to eat my children, I'd rather eat them first."

That was the chilling reply from a mother Long-Tailed Sun Skink. By human standards, these female lizards are terrible mothers. After laying their eggs, they abandon the nest, leaving the eggs unprotected.

But one population of long-tailed sun lizards living on an island in the Pacific Ocean seems to be a little more responsible. They often guard their eggs for a week, to ensure their young have a good chance of survival.

Evolution has developed a maternal instinct for this particular lizard population, because on the island they live there is a species of snake (Oligodon formosanus) that specializes in eating lizard eggs.

When a snake invades the nest, the mother long-tailed sun lizard will immediately fight fiercely with the snake to protect her eggs. They seem like model mothers, right? But a tragedy will happen, if the frequency of snake attacks is too great.

A 2008 observational study in the wild, along with field experiments, showed that if egg-eating snakes raid lizard nests too frequently and the female lizards know they can no longer fight back, the mother lizard will eat all of her eggs before the babies are eaten by the snakes.

What a heartbreakingly desperate reaction.

But why do they do this? It is possible that evolution has given the lizards two options, weighing the costs of two scenarios. One is that they reluctantly fight the snake and fail, and then have to watch the snake eat their eggs. Two is that they would rather eat their own eggs first, to save strength and energy for the next breeding season.

To optimize the continuation of their species, the long-tailed sun lizard will choose option number two. They may despair and die out, eating all their eggs, but they will definitely not die out, they know they need energy to lay the next batch of eggs. It is better to do that than let the eggs fall into the mouths of their enemies.

"My family is too poor, I can't feed that many mouths"

Buried beetle.

Burying Beetles said through tears. They are so called because they regularly bury the bodies of their prey, usually small animals or birds, in the ground to create nests for their young. It is a clever survival strategy, because as soon as they lay their eggs in the pile of carcasses, the hatchlings will have food to feed themselves.

The problem is that burial beetles tend to lay too many eggs, and the prey they find is not always large. There are several reasons why they lay so many eggs. First, they can increase their survival rate if their eggs go bad. Second, the more babies they produce, the better their survival rate in the wild, when faced with predators or any other cause that might kill them.

However, overpopulation can also be disastrous if the young beetles do not find enough food early in their lives. Competition for a limited food source can cause large numbers of young burial beetles to starve to death.

The mother beetles had to do something, while they were in labor and unable to forage for food. Evolution gave them a two-pronged suggestion: Eat the late-hatching eggs.

When a burial beetle finds itself with too many young in its nest, it will eat the slow-developing eggs. This behavior has been documented by zoologists since 1980, but it wasn't until 2013 that it was studied in detail.

It turns out that the late-hatching offspring of the burying beetle are often less healthy than the early-hatching eggs . So the beetle not only eliminates them to increase the survival chances of its stronger siblings, but also performs an act of 'natural selection' —though not quite natural—to help improve the quality of the genetic code of its offspring.

"They are sick, I can't let them all get sick"

It should be said that Japanese Giant Salamander males are model fathers. In this reptile species, the responsibility of caring for the eggs does not belong to the female, but is entrusted to the father.

The Japanese giant salamander will care for its eggs and young for 7 months, which is quite a long time compared to the maternal responsibilities of the long-tailed sun lizard above, which, if you remember, only cares for its young for 1 week.

During these 7 months, the salamander fathers are very responsible. They often use their tails to fan the water to add oxygen to the nest for the eggs.

In particular, salamanders clean their egg nests very carefully. They will pick up organic debris that accidentally flies into the nest, to prevent it from becoming a breeding ground for a very dangerous pathogen for eggs: fungus.

Adult salamanders do not suffer health problems from the fungus. But their babies do. Fungal infections can kill baby salamanders. And the fungus can spread quickly in a nest of newborn salamanders.

So if the male salamanders clean out the nest and somehow the fungus manages to grow and infect some of the eggs, the father salamander will devour those eggs. The goal is to protect the remaining eggs from spreading the fungus.

This behavior is called ' sanitary cannibalism .' And it seems it doesn't stop at just eating eggs. Male salamanders have sometimes been caught eating infected young when they're too sick to recover.

It was a tough decision for the Japanese giant salamander.

"I don't eat my children, they just donate a little blood to me."

dracula ant

While some animals devour their eggs and young, others will bite their young without killing them. Take the Dracula ant, for example, which, as the name suggests, will drink the blood of its young.

Well, not exactly blood. Like other insects, ants have plasma as a circulating fluid in their bodies, allowing them to store water and nutrients they need to function. Some species of ants have been seen sucking plasma from larvae.

Adult ants, usually queens, will suck the plasma directly from the young by using their mandibles to bite straight into their backs. Luckily for the young ants, the wound heals quickly without leaving any scars.

Strangely enough, evolution seems to have equipped young dracula ants with the instinct to donate blood to their parents. They have small cracks on their backs from an early age, allowing adult ants to reach in and bite . With just a light bite, the dracula ant can slide its jaws into the larva's back and suck out its blood plasma.

Why do they do this? It turns out that ant colonies sometimes experience famine, when the ants cannot find food. At this time, each young larva is willing to sacrifice a little of its plasma to the queen ant in the colony.

It seems that only queen ants suck the blood of their young . And they only do so in extreme situations. If the worker ants can still bring food back, they never suck the blood of their young.

Another thing, queen dracula ants only feed on larvae if they count enough larvae in the nest to maintain the population. If the number of larvae is too small, they would rather starve to let the young larvae develop.

So, this is not exactly cannibalism, the dracula ant larvae are just sacrificing themselves for their mother and maternal love.

"Too young to be a father, I still want to mate"

Striped Chinook.

This is perhaps the most irresponsible and reprehensible answer in the animal kingdom. Barred-Chin Blenny, they eat their young only because they are eager to mate rather than have to raise their young to adulthood.

Like the Japanese salamander, the responsibility of egg care and rearing of young is delegated to the males rather than the females. But male striped chins are playful and irresponsible fathers. Not only will they fan the water to bring more oxygen into the nest, but they will sometimes throw the eggs out of the nest to avoid fatherhood.

It turns out that this fish has a sex hormone called androgens . A male fish can only mate if it has enough androgens in its body. In one experiment, scientists gave eggs to male striped chin fish that had not laid eggs. They found that the sex hormone levels in these fish dropped and they could no longer mate.

In contrast, if they removed the eggs from the male striped chinook's nests, the fish immediately increased their androgen levels and went back to mating with the female, producing a new batch of offspring. And they did so within 24 hours.

This experiment explains why in the wild, striped chinstrap fish are sometimes caught eating their own eggs. And if they don't eat them, they throw the eggs out of the nest so they don't have to be fathers.

Scientists are still trying to figure out why this happens. It seems illogical that striped chinook fish would spend so much time and effort reproducing, only to abandon or eat their own offspring.

One possible answer is that when male striped chinook fish find their clutch of eggs too small or of poor quality, they will destroy the entire clutch and start a new one. If they do not destroy the eggs, the androgen levels in their bodies will not be high enough to mate again.

The impatient striped chinstrap fathers cannot wait to raise these eggs into weak adults before returning to single life to mate. They think their life cycle is short, so it is best to lay a new batch of eggs right away.

To the human eye, this behavior seems irresponsible, heartless, and reprehensible. But perhaps it is the very heartlessness of the striped chinook that ensures the survival of their species, at least for the eggs they have decided not to eat.