While many sharks lay eggs, the iconic great white gives birth to live pups! But this isn’t any ordinary birth – the details are a little weirder…
Great white sharks lay eggs and give birth!
In biology, animals that lay eggs are usually called oviparous. Most live-birthing animals like mammals are called viviparous. As it happens, great white sharks aren’t viviparous but they still give birth! So, what do these terms mean, and how does it work?
We’re going to take a look at how sharks reproduce, how long it takes, and what exactly comes out of them. But don’t worry, there’s only one more technical term to remember!
What you’ll find might surprise you. These sharks don’t give up their secrets easily, and we are still trying to solve a lot of the mysteries of the largest predatory fish on earth.
How do great white sharks reproduce?
This is an easy one! The short answer is: we don’t know!
If you’re looking for a career in marine biology, this might be a good place to start.
Lots of sharks, including white sharks, do very badly in captivity and travel tremendous distances every day. This makes them exceptionally hard to study, particularly when it comes to mating, so we need all the help we can get to find the answers to some of these questions.
Here’s what we do know:
White sharks are ovoviviparous. This might be better understood as somewhere between viviparous and oviparous.
Essentially, what it comes down to is that these sharks technically do lay eggs; they’re just hatching inside the mother’s body before they come out. This means, like a chicken, a great white embryo starts life feeding on a yolk, rather than directly from the mother as in placental animals.
They’re born with a full set of teeth and left to fend for themselves. Many will die from predation at this stage, most likely from other sharks, including great whites!
The males become sexually mature at around 9-10 years, the females at somewhere around 14-16 years old.
That’s a long time to reach maturity in the ocean, but if they survive, these fish live upwards of seventy years. What happens next is a bit of a mystery, but there are some things we can assume based on what we know about other sharks and what we’ve observed in the wild.
Here’s what we think:
From knowing other ovoviviparous animals and observing great whites in the wild, we can confidently infer that:
- Females suffer from “love bites”, thought to be scars from the male in during mating
- Fertilization takes place internally, via copulation
- The babies are birthed in warmer, subtropical, spring waters
- California and New York are two locations for possible white shark nurseries
Now we’re beginning to paint a picture of the reproductive cycle of the great white shark, but there’s still some information missing. How long does this all take? The truth is, even this is something we’re still trying to figure out.
Great white shark gestation period
The gestation period for a great white shark is thought to be 12 months.
This implies that a mother may only be able to reproduce once every two years. These are long-lived fish with a slow reproductive cycle, so they are particularly vulnerable to population decline.
Fertilized eggs are retained in the female’s body, and after the embryo develops over the course of a year, it is birthed into warm waters – with a full set of teeth – to fend for itself.
How many babies do great white sharks have at a time?
Great white sharks give birth to between 2 and 14 pups. While nobody has ever witnessed a white shark giving birth, pregnant females have been found, and their embryos recorded, allowing us a rare glimpse into their reproductive patterns.
It seems that some of the eggs inside the adult don’t develop or that they are perhaps eaten by the pups who get there first. So even before birth, these sharks are formidable predators!
The survivors are born in the Spring and are all set for a life of hunting alone. The birthing process is a mystery, but from certain clues, we can figure out roughly how big they are when they come out.
Baby great white shark size and weight
The smallest free-swimming specimen we’ve ever recorded was 41 inches and 36lb, though embryos inside a pregnant white shark have been measured to be as large as 59 inches!
These are big babies, but how do we estimate how young a shark is?
As a white shark grows, its proportions change, and biologists can use these proportions to narrow down the shark’s age.
Another way to tell that a white shark is a newborn is the fresh umbilical scars – yes, belly buttons!
We said that white sharks feed on a yolk rather than directly from the mother, and this is true at first, but some ovoviviparous sharks do form a sort of placental connection for nutrient exchange as they develop. And great white pups are one of them! When they’re born, these cords disconnect, and a cute little shark belly button is left behind.
Great whites are truly prehistoric animals, but we’re still only scratching the surface of what we know about their behaviors.
These elusive predators keep their reproductive secrets well guarded, mating and giving birth in private. As such, most of what we know has to be inferred from observing them in other contexts.
One thing we do know, though, is that great whites give birth to live young after laying eggs that are protected inside the mother’s body for up to 12 months.
The pups are then left to fend for themselves and slowly grow to sexual maturity themselves over 9-16 years. The rest is left to discover!
Perhaps the next generation of marine biologists will be the ones to unlock the secrets of this majestic fish.