Episode 189 – Japanese Sleeper Ray: A Shocking Pancake

“…and today we’re talking about a spicy dish. But more on that later.”

Deep in the water where the fish hang out, lives a small sleepy saucer we know not too much about

He’s a zap zap fish with a zap zap belly

And his neat electric organs turn your insides into jelly

He hides beneath the sand and waits for food to flutter by

So he can snatch it up and wait for another passerby

Cause he’s a zap zap fish with a zap zap belly

And it’s just how he survives in Life Death and Taxonomy


  • They are round, disk-shaped rays with flat bodies. 
  • They have a similar top down shape as a horseshoe crab, but they also have a longer fishy tale. 
  • They have soft skin and lack firm fish scales which the wiki writer went above and beyond by calling “dermal denticles.”
  • They have a spotted, mottled look with a light brown tannish base and dark brown spots. But some are a monochromatic tan color.

Measure Up

Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com. We don’t have a new Measure Up intro!

  1. Cassowary
  2. Koala
  3. Kangaroo
  4. Tortoise


  • 40 cm (16 in)
  • How many Japanese Sleeper Rays go into the height of Eternatus, the poison dragon pokemon that was introduced in Pokemon Sun and Moon?
  • Hint: Eternatus the tallest pokemon when it goes into its special Eternamax Eternatus phase that more than doubles its size. Even without that, it’s the tallest pokemon. 
  • 50 rays. Eternatus is 65’07” or 20.0 m.


  • 12–23 m (39–75 ft)
  • How many Japanese Sleeper Rays go into the height of the most recent iteration of Godzilla?
  • Hint: As the King of Monsters in the 2019 Godzilla movie and in his face off with King Kong, he is the tallest he’s ever been. A far cry from his original 164 feet (50 meters) in 1954.
  • 5.2 dive depths. Godzilla is 394 feet (120 meters).

Fast Facts

Japanese sleeper rays are so called for their lackadaisical approach to life. They spend most of their time on the sea floor buried beneath the sediment. 

They live in the northwestern pacific ocean on th continental shelf near Japan, Korea, China, and Taiwan. They’re found near and far away from shore, but they prefer sandy areas near coral reefs. They essentially like oceanic suburbia. 

These rays are viviparous like many of their shark kin. They develop on a diet of yolk and then histroph, which is milk from the uterus. 

They are born into litters of five or less. And they all celebrate their b’nei mitzvah when they’re around 23 to 37 cm long. 

If you want one as a pet, you’re out of luck because they don’t adapt well to captivity. Still, they may be bycatch in shrimp fishing. They have no commercial use and they would be thrown back but they usually don’t survive being caught. This may have contributed to their decline, since the fishing trade in East Asian waters is extensive. 

Major Fact: Electric Tough Love

Like most fish, the Japanese sleeper ray has a litany of predators to keep an eye out for like the blotchy swell shark.

Fish use all kinds of tactics to both catch food and avoid being caught as food. Some use camouflage, some use speed, some just hide, others use venom or poison. But this ray uses a sturdy pair of duracels.

Like the electric eel that we covered, weaponized electricity in animals comes from specialized electric organs. But in the sleeper ray, these organs are made of electrocytes, cells filled with a jelly substance that are stacked in vertical columns. Since each organ is made up of these columns, they function as a series of batteries with their poles aligned in parallel.

This allows them to deliver an electric shock of up to 80 volts. Remember that voltage is the speed of the electrons in electricity while amps are the volume, or number of electrons. So just knowing the volts doesn’t tell us all that much. If something produces 10K volts but 0.0001 amps, it’s not producing much.

However, I could not find a single place that went into detail about the current these guys can produce. But I did find one source that said that Atlantic Torpedo Rays, another species of electric ray, can produce up to 30 amps with 50-200 volts.

To put it into perspective, a dishwasher uses about 10 amps while a lightning strike is over 20K. This isn’t necessarily lethal to humans, but it can be very painful and could kill someone with a heart issue, though no cases have been reported.

The main use for this electric attack is for defense against the dark arts but some sparse observations could point to using it for catching prey. Fishermen often catch these guys in their nets, but the rays usually discharge their electricity as soon as they are disturbed and it takes time for the batteries to charge again.

They’ve been fished for commercial purposes in the past since their oil was apparently as useful as whale oil for lamps and was even used for old timey medicinal purposes.

Ending: So sleep well, pick your battles, and shock the haters with your natural energy like the Japanese sleeper ray here in Life, Death, and Taxonomy.

Episode 173 – Bluestreak Cleaner Wrasse: The King of Cleaners

“…and today we’re talking about a fish that enjoys working at the carwash. More on that later.”

When you run a lucrative maritime cleaning service, you gotta protect your turf. The dominant bluestreak cleaner wrasse defends its territory, its business, and its family on a daily basis. But when the don disappears, it’s up to one of his leading ladies to fill his shoes. But being willing to fill any role is part of surviving here in Life, Death, and Taxonomy.

Episode 167 – Giant Oarfish: Seismic Sensitivity?

“…and today we’re talking about the longest boy in the ocean. But more on that later.”

Earthquakes are some of the most destructive events on this planet, snuffing out lives by the thousands and destroying entire cities. The worst part is, we can’t really predict them in advance-or can we? The elusive oarfish is often considered an incredibly long harbinger of earthquakes, and some people see sightings of them as a sign of impending disaster. Let’s find out just how much truth there is to this here in Life, Death, and Taxonomy.

Episode 157 – Blobfish: Blobby Fisher

“…and today we’re talking about a waterlogged football with eyes and a taste for shrimp. But more on that later.”

The blobfish might be the subject of cruel internet memes for many a year, but that digital ridicule may be unduly bestowed upon our deep-sea friend. He may look goofy, but that’s just because he’s far outside his natural habitat. Living at the bottom of the ocean, the blobfish actually has a pretty remarkable way of keeping it all together here in Life, Death, and Taxonomy.

Episode 153 – Blanket Octopus: Let the Octopus Win

“…Today we’re talking about a cephalopod that wears a beautiful gown. But more on that later.”

The ocean is home to many a strange and wondrous creature, but few are so strange as the blanket octopus. Worthy of its name, the blocktopus drifts and flutters with dazzling colors across the pelagic seas. But unfurling your snuggie has consequences in the deep blue, so the blanket octopus needs to have some improvised weapons at its disposal. But that’s just how you survive here in Life, Death, and Taxonomy.

Episode 143 – Barreleye: The Spookiest Fish

“…and today we’re talking about a mysterious organic, deep-diving submarine. But more on that later.”

Deep down at the bottom of the ocean, there sits an alien monster fish that stares up straight through its own skull to spy prey: the barreleye. How does it do this? By being one of the weirdest creatures alive, even for deep-sea animals—and that’s saying something! But looking strange is just a fortunate side effect of being an empty-headed harbinger of jellyfish death from below here in LDT.

Episode 140 – Mako Shark: Hot-Blooded Hotrod

Sharks are a primordial design. A torpedo built to catch and shred prey. These cold black eyes, like a doll’s eyes, are nothing but dark pools of basic, rudimentary instinct, right? Well some sharks are built differently than their kin. The mako shark is one of a few fish with an interesting adaptation that is foreign among fish. These hot-blooded predators of the temperate ocean have an ability that gives them an edge against their most elusive food sources. Sometimes the only way to survive is chase down and catch Life, Death, and Taxonomy…

Episode 139 – Giant Manta Ray: A Focused Fish

“…and today we’re talking about a buccal pumping pup sucking histotroph in huge chunks. That sentence will only get grosser when you know what those words mean. But more on that later…”

Sometimes the biggest giants are the gentlest giants. But this gentle giant is also a genius giant. While the oceanic manta ray might not be smarter than a fifth-grader, it does use its brain in ways that would make other fish extremely sad and jealous if they had any feelings. In fact, it’s those feelings that make the manta ray a prime candidate for smartest swimming blanket. But when you’re the biggest fish in the pond, you can afford a little self-awareness here in Life, Death, and Taxonomy.

Episode 131 – Eastern Emerald Elysia: An Animalian Rebel

“…And today we’re talking about a naughty slug that doesn’t play by the rules. But more on that later.”

Hi, LDT listeners. You’re about to hear something special: Life, Death and Taxonomy’s first ever theme song. We’ve long set the mood with free to use web found music, but thanks to our friend Casy, we now have a song that is unique to us! Help us show our appreciation by checking out more of Casy’s music at her YouTube channel. Click the link on LDTaxonomy.com or search Casy Michelle on YouTube! Let’s get into the episode!

Some animals just prefer not to play by the rules. Animals change lanes all the time. Bats are mammals that fly. Sharks are fish that give birth to live young. But most animals stick to their kingdom, except for a particular sea slug. When all others spend their lives hunting and gathering for sustenance, this slug goes out of bounds to borrow a technique. But creatures that prove that some rules are made to be broken often find the most success in Life, Death, and Taxonomy.