The genus name Carcharodon is from the Greek "karcharos" = sharpen and "odous" = teeth. The species name carcharias, also Greek, means “point” or “type of shark.” This actually lends to one of its nicknames, “white pointer” (in Australia). They are also known as white death, due to their reputation of ‘attacking’ surfers.
These mackerel sharks (family Lamnidae) can get large (up to 6.1 m total length, weighing up to 1.9 tons). If you’re American, 6.1 meters translates roughly to 20 feet, and 1.9 tons 3,800 lbs.
Think about that next time you ride a school bus, or see one pass you by.
These animals are characterized by a K-selected life history (slow growing, late maturing, and long-lived species with low fecundity) and cosmopolitan range.
You thought I was joking? No, look at that map! These animal can just about be seen anywhere. However, even though it is practically seen anywhere and has garnered the interest of both the science and public realms, large gaps still exist in our understanding of these sharks.
“There’s more than one population of great white sharks?”
Look at how widespread they are- of course there is!
There have even been pups caught in that area (but of course, when I scour the internet for the ONE video I saw months ago, I can’t find it)!
Alright, I’m going to get really scientific here for a second, so head’s up to the young readers: Mitochondrial DNA (mtDNA) shows that SA and ANZ sharks are genetically different populations! And the NEP population is a descendant of the ANZ group.
In the NEP population, data from satellite pop-up achival transmitting (PAT) tags have shown that white sharks tagged in California and in Guadalupe Island, Mexico share their regions with each other. Sharing is caring, right?
Talk about one heck of a trip, huh?
Although not much is known about white shark reproduction, they are viviparous (embryos hatching in the uterus, with the female giving birth to live young); embryos are nourished through oophagy (remember that sibling cannibalism?). While in the uterus, the embryonic white sharks swallow their own sets of shedded teeth; this may be to reutilize calcium and other minerals.
It is possible that any one female only reproduces biennually, mating soon after giving birth, but this remains to be confirmed. Gestation time is also unknown, but is thought to be quite long, possibly up to one year.
Everyone knows the famous shots of great whites breaching out of the water to snag a seal for a snacky-poo. In order to catch these fast prey, white sharks are have the rete-mirable, like the mako shark. Refresher: the rete-mirable is closely packed veins/arteries on either side of the shark that helps in conserving heat (especially in the stomach) , making the shark warmer than the surrounding environment. This allows them internally regulate their body temperature.
If you don’t think that’s cool, you can leave now.
But, seals aren’t the only thing they eat! These sharks can eat different prey based on their age, size, and location. Great white sharks 3 meters in length or smaller have a diet comprised of predominantly fish. After this youth stage, they exhibit a dietary shift to larger prey (i.e. marine mammals) . However, many retain their multi-prey tastes as they age.
“That’s cool! How do we know this?”
In 2008, scientists wanted to figure out how hard a great white shark could bite. Findings showed a shark man than 6.1 m (20 ft) could exert a bite force of over 18k newtons (or 4,000 lbf). AKA, OUCH.
This shark gets a really bad rap for human attacks, but please don’t think they’re man-eaters! I’ve swam with them without a cage and they didn’t eat me—and I’m literally bite sized. They are not just swimming around and being like, “You know what I want for brekky today? Human. And for lunch? Human. And dinner? HUMAN. Man, I love this human diet.”
Please, if you take anything away from this post, remember that.
WE ARE NOT ON THE MENU.
Seals. Seals are on the menu, though. I mean, check this out:
I also got to bait rope these sharks in South Africa, and THAT was fun. Thanks for letting me squee about my thesis topic, guys!