In this week's episode, we look at a couple of so-called living fossils: the tuatara and the lamprey. One of them hasn't changed appreciably in almost 400 million years. Tune in to find out which one and learn about how gross it is and how cute the other one is! (I may be biased.) (re-recorded audio) The adorable tuatara! It eats anything, including baby tuataras. Not cool, lizardy guy: A face not even a mother could love. The sea lamprey: A recently discovered fossil lamprey, complete with impression of its body: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week’s episode is about my favorite reptile and a revolting sea creature, and just to be clear, those are two different animals. If you look at a tuatara, it appears pretty ordinary. It’s a brownish-grayish-green lizard with lighter-colored spines along its back, and it can grow to about two feet long, or 61 cm. It’s a hefty lizard, sure, but you’d probably think it was nothing special. But dang, is it special. First of all, it’s not strictly a lizard. It’s the only surviving member of its own order, Rhynchocephalia. It also has many physical traits not shared by lizards—or any other living reptile. Or mammal. Or bird. Or anything else. Its teeth, for instance. The tuatara has two rows of teeth in the upper jaw, one in the lower, with the lower jaw’s teeth fitting neatly between the two upper rows. Some snakes have two upper rows of teeth and one lower row, but not arranged like the tuatara’s. Not to mention that the tuatara’s teeth aren’t even teeth at all. They’re just pointy projections of the jaw bone. The tuatara also chews in a literally unique way. When the lower teeth mesh between the upper rows of teeth, the animal moves its jaw forward and back. This slices its food against the sharp tooth edges. The tuatara also has a third eye. I’m not making this up. It legit has a photoreceptor on top of its head called the parietal (pahRAYetal) eye with a lens, cornea, retina, and so forth. Hatchling tuataras have a translucent patch of skin above the eye, but as the hatchling grows and molts its skin, the patch darkens until the third eye is no longer visible. Researchers think it may help with thermoregulation and hormone production. The tuatara isn’t the only creature with a third eye, but it has the most well developed one. Like the turtle, the tuatara has a primitive auditory system. It has no external ears and no eardrum, although it can hear. Its skeleton has some features apparently retained from its fish ancestry, such as its spine and some aspects of its ribs. Males don’t have a penis—but a lot of birds don’t either and we still have lots of birds, so obviously they make it work. Because it has such a slow metabolism—the lowest body temperature of any other reptile—the tuatara grows slowly. It won’t reach breeding age until it’s ten to twenty years old, and females only lay eggs about once every four years. The average lifespan of a tuatara is 60 years. Researchers believe it could live to 200 years in captivity. Baby tuataras are active in the daytime, probably so their parents won’t eat them. Tuataras eat pretty much anything they can catch. Adult tuataras are active at night, and sleep during the day in dens. Sometimes a tuatara digs its own den, sometimes it shares a den with burrowing seabirds. The birds leave in the morning and the tuatara comes home to sleep until night, when the birds return. The Tuatara is native to New Zealand, and in an all-too-common situation, when people showed up, the tuatara promptly went extinct on the mainland. It was restricted to 35 islands where it was mostly safe from introduced rats, until its reintroduction in the fenced Karori Sanctuary in 2005. Tuataras have begun to breed in the sanctuary. One thing I didn’t know about New Zealand—one of many many things, since pretty much all of my New Zealand knowledge comes from watchi...