Shark Week

So You Think You Know Sharks — 15 True Facts ‘Jaws’ Didn’t Teach Us

Have you wondered why sand tiger sharks kill their siblings inside the uterus? — Time to learn more about sharks.

Rui Alves
11 min readJul 27, 2022


Photo by Moon on Unsplash

Sharks are fascinating creatures that have evolved over the last 450 million years to adapt to environmental changes. They’ve become pop culture icons for all the wrong reasons, yet their beauty and grace never cease to astound me.

The Discovery Channel launched a new edition of Shark Week on Sunday, the 24th. I got the opportunity to watch the documentaries The Great White Intersection and The Great White Open Ocean, which inspired me to write about why these creatures are among the most well-adapted marine species and most effective predators on Earth.

Sharks have always been fascinating creatures. You might think they are highly aggressive towards humans when you see them in movies like Jaws, but the truth is they are vital to the ecological balance, and fatal attacks on humans are relatively rare.

So, let’s dive into the world of sharks and learn more about their lives, habits, traits, and unique anatomical features.

1 — Sand tiger sharks’ embryos are cannibals

It’s no secret that sharks are some of the fiercest creatures in the sea, but did you know they’re pretty vicious too?

Well, not all sharks — just some species.

It’s true: Sand tiger sharks are known to practice a form of sibling-killing called intrauterine cannibalization. The apex embryo will hunt and kill its brothers and sisters while still in the womb. Afterward, it will have free access to all the unfertilized ova carried in the uterus and consume them (oophagy).

“Embryophagy,” also known as “adelphophagy” (“eating one’s sibling”), is a practice found in certain species of animals, including sand tiger sharks. In this way, the more robust embryos develop faster, which helps them catch prey when born.

Since sand tiger shark females have two uteri, only two hatchlings will be born.



Rui Alves

Hi, I'm Rui Alves, teacher, published poet, scriptwriter, digital vagabond, bass player & alchemist of sound. Look me up: