THE BIOLOGY OF THE TUATARA

This is a tuatara and while it may look like a lizard, it is not. You are more closely related to a kangaroo than this thing is to a lizard. They belong to the squamate group, tons of species, over 10,000. But the tuatara, they are on this lonely branch right here, Rhynchocephalia, and they are literally the very last species in that entire group. Species can only be found on and some of the really small islands surrounding New Zealand. And the sad thing here, the last of a very, very ancient lineage. And rats were brought to New Zealand, they aren't really able to survive there anymore. Now, they've been evolving down their own path for so long, there are some interesting differences here between the tuatara and the lizards with the way they eat. For example, the tuatara on the top of their mouth, they have two rows of teeth. On the bottom, they have one, and the bottom right in between those two. So it's essentially sawing as it's eating things like little birds. They also don't have a penis. Unique there. The only other even close to them in that. That's the birds. They put their cloacas up next to each other and essentially rub them. And people will bring up the third eye of the tuatara. They have a parietal eye on their head. That's not unique to their lineage, though. That's seen in lots of different lizards, even frogs. We have remnants of that parietal third eye. I can't actually see images, but they can see light, so it can kind of track light. One of the most interesting things about the tuatara reptiles, handle the cold pretty efficiently. And that's because their body temperature runs lower than most other reptiles. That metabolism also reason they live so long, well over 100 years, reaching sexual maturity around the ages of 13 to 20 or so, which again, that's part of why it's so bad that rats made it to their island. But anyways, this study published in 2021 had an absolutely groundbreaking discovery. The tuatara genome, this might be reasons survive in those colder temperatures better. And that's that they have two deeply divergent versions of mtDNA. Something similar has been observed in mussels, every other animal, our lineage that's been evolving alongside us. Talked about mitochondria, it originated as bacteria. So the mtDNA, that's not the DNA of this organism that's living inside of us, evolving alongside us, around 7-8 MYA. Their version seems to have experienced a duplication, then on two different lineages continued evolving differently, accumulating different adaptations, evolving down their own path. In the tuatara today, that might be part of why they are so adaptable. Just fascinating stuff. The tuatara, an animal that looks like a lizard. And after the great dying, like this group, super successful. They pretty much filled the role that small lizards play today. It wasn't until the Jurassic and then during the Cretaceous swapped and the squamates became more common, while this group, they fizzled out. And like I said earlier today, we have one last species from this entire lineage.