Claire Corlett

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Why Most Sand Tiger Sharks Die in the Womb

Why Most Sand Tiger Sharks Die in the Womb


As humans, we tend to think of the womb as
a nice, warm, safe place. But if you were a sand tiger shark, the womb might seem like
the most dangerous place on the planet. I’m Anna Rothschild, and this is Gross Science. Sand tiger sharks are large sharks that live
in warm and temperate waters throughout most of the world. Females have two wombs—two
“uteri.” And when a female’s pregnant, she can have about six or seven babies in
each womb, each one in its own egg case. Eventually, one of the babies will hatch from
its egg. This hatchling might be little, but it actually already has a set of razor sharp
teeth. In fact, one scientist claims he was bitten by a fetus while he was dissecting
a dead female! There’s a reason for these sharp teeth though.
You see, soon after emerging, the hatchling will start devouring its growing brothers
and sisters until it eats up every last one in the womb, a process called “embryonic
cannibalism.” In the end the mother gives birth to just two babies—the cannibal pup
from each uterus. This might just sound like sibling rivalry
gone wild, but the hatchling actually gets a huge benefit from this blood bath. By feeding
on the flesh of its siblings, the hatchling grows quite large. In fact, by the time it’s
born, it can be over three feet long! And this gives it an advantage in the ocean—very
few predators would dare hunt a three-foot-long killer with razor sharp teeth. There might be another reason for this strange
process, as well. It turns out that female sand tiger sharks mate with multiple males,
and it’s possible that they have little choice in the matter, though they might get
to choose who they mate with first. Embryonic cannibalism may be a way for them to take
back control. You see, females can carry the babies of multiple males at the same time.
So, a female might mate with her favorite male first, to give that male’s babies a
head start to becoming
the cannibal hatchling. Ew.

88 comments on “Why Most Sand Tiger Sharks Die in the Womb

  1. Anna from a business point of view i recommend you try get a video to go viral, your channel is clearly well produced but you lack viewership because you're do new, a viral video would get the word out 🙂

  2. In relation to this video, there is actually growing evidence that we are all conceived as twins, and that those of us who aren't also born as twins are the ones who indulged in embryonic cannibalism.

  3. That photo of the single male shark (with another shark in the far back) looks like it was taken at Point Defiance Zoo and Aquarium….

  4. Coconut juice are used in many different way like treating dry skin. can it help kill worms or parasite in your gut???

  5. Can anyone tell me the reason why evolution chose this method of birth instead of  using all of the available resources to cater for one uterus and one hatchling? It's the same result both ways, the hatchling will be bigger and more healthy.

  6. You have this magnetic charisma that is very pleasing to watch. As always, amazing vid

  7. I'd really appreciate it if you would start to add the metric system to your videos. If you want to keep the imperial system – fine – but at least in the on-video text, add the sizes in cm as well, please. That way I would not have to stop halfway through the video and calculate how much "3 foot" is. Thank you.

  8. i bet mother nature was like bored and she watches the hatchlings devour the others and she is gonna scream all come in one co es out

  9. thank you bro science you are just amazing now I can tell my parents that I learn something from YouTube about science

  10. I think that you should make a video about kombucha. It is a symbiotic bacteria and yeast embedded in cellulose layer. It ferments tea and produces refreshing cider -taste drink. The cellulose is produced by bacteria (BC) and its look is pretty gross.
    BC is important for microorganisms to survive in liquid and for people it has multiple uses like in electronics or for artificial skin.

  11. Okwhat if twonhatch at the same time from the same womb will they try and eat each other????? Oh and can you do a vid of why blood is red???

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