Sorry to my Patreon subscribers, since this is mostly a rerun episode from April 2019. It's a fun one, though!

The teensy pumpkin toadlet [photo by Diogo B. Provete - http://calphotos.berkeley.edu, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=6271494]:



The electromagnetic spectrum. Look how tiny the visible light spectrum is on this scale! [By NASA - https://science.nasa.gov/ems/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=97302056]:



Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This was supposed to be the 2023 discoveries episode, but not only have I had a really busy week that’s kept me from finishing the research, I’m also coming down with a cold. My voice still sounds okay right now but considering how I feel, it’s not going to sound good for long, and I need to finish the March Patreon episode too! I decided to rerun a very old Patreon episode this week to allow me time to finish the March Patreon episode before my voice turns into an unintelligible croak. I did drop in some fresh audio to correct a mistake I made in the original episode and add some new information.

This is one of my favorite Patreon episodes and I hope you like it too. It’s about animals that can see ultraviolet light.

I was going to make this a frog news episode, but I started writing about a tiny frog from

Brazil called the pumpkin toadlet and the episode veered off in a very interesting direction. But let’s start with that frog.

It’s called the pumpkin toadlet because it’s an orangey-yellow color that is just about the same color as pureed pumpkin. It’s poisonous and lives in the forests of Brazil. During mating season, the pumpkin toadlet comes out during the day, walking around making little buzzing noises. Researchers assumed those were mating calls until they started studying how the pumpkin toadlet and its relations process sounds. It turns out that the pumpkin toadlet probably can’t even hear its own buzzing noise. But they did discover that the pumpkin toadlet fluoresces brightly under UV light.

We’ve talked about this phenomenon before, back in the Patreon episode about animals that glow. Quite a lot of frogs turn out to fluoresce in ultraviolet light, which is a component of daylight. That explains why the pumpkin toadlet comes out during the day in mating season. It wants to be seen by potential mates. It’s actually the frog’s bones that fluoresce, but since it has very thin skin without dark pigment cells, the ultraviolet light can light up the bones.

I wanted to make sure I gave everyone the correct information about ultraviolet light, so I started researching it…and that led me down this rabbit hole. What animals can see in ultraviolet light? Can any humans see ultraviolet light? What does it look like?

Light is made up of waves of varying lengths. The retina at the back of your eyeball contains two types of cells, rods and cones, which are named for their shapes. Rods are for low-light vision and cones are for detail and color vision.

Humans have more cones than rods because we’re diurnal animals, meaning we’re most active during the day. Animals that are mostly nocturnal have more rods than cones, which help them see in low light although they don’t see color as well or sometimes at all as a result.

Most humans can see any color that’s a mixture of red, green, and blue, since we have three types of cone cells that react to wavelengths roughly equivalent to those three colors. Some people have what’s called red-green color blindness, which means either the person doesn’t have cones that sense the color red or cones that sense the color green. Various shades of green and red look alike for these people. Red-green color blindness is much more common in men than in women, with as many as 8% of men having the condition. A lot of times they don’t even know it. When I did my student teaching in a first grade class,