# Champion of the Week: A Glass-Headed Fish, a Blood-Squirting Lizard, a Sparrow-Sized Bug, a Blushing Sand Swimmer, and the Mouthless Worm That Ate Them All

> Five weekday winners walk into the ring. One of them does not have a mouth, and somehow that is the one you should be afraid of.

By someone who loves to compare irrelevant things. Weekend Special - Champion of the Week.

## Contestants

### Barreleye (Macropinna microstoma)
Taxonomy: Actinopterygii > Argentiniformes > Opisthoproctidae > Macropinna > 
Shows up to the fight already able to see through you, via its own forehead.
- COOL - Head: Transparent fluid-filled dome you can see the eyes through
- WEIRD - Eyes: Green tubes that rotate to look up, then swivel forward to eat
- WEIRD - Fake face: The two 'eyes' on the front are actually its nostrils
Photo: NOAA Ocean Exploration, Exploring Pelagic Biodiversity of the Gulf of Alaska expedition, Public domain (NOAA, PD-USGov) (Wikimedia Commons) - https://commons.wikimedia.org/wiki/File:Barreleye-fish_GoK.jpg

### Texas Horned Lizard (Phrynosoma cornutum)
Taxonomy: Reptilia > Squamata > Phrynosomatidae > Phrynosoma > 
Loses a real amount of blood out of its eyeballs and calls it self-defense.
- GROSS - Panic button: Squirts an aimed stream of blood from its eyes up to 5 feet
- COOL - Target: Blood tastes foul specifically to dogs and coyotes
- WEIRD - Fuel: Up to ~70% of its diet is harvester ants, eaten one at a time
Photo: Patrick Alexander, CC0 1.0 (Wikimedia Commons) - https://commons.wikimedia.org/wiki/File:Phrynosoma_cornutum_-_Flickr_-_aspidoscelis.jpg

### Wetapunga (Giant Weta) (Deinacrida heteracantha)
Taxonomy: Insecta > Orthoptera > Anostostomatidae > Deinacrida > 
Brought the most body mass to a fight it fully intended to sleep through.
- COOL - Weight: Gravid female up to ~35 g, heavier than a house sparrow
- WEIRD - Range: Survives naturally on one island only, Hauturu
- COOL - Age: Body plan basically unchanged for ~190 million years
Photo: Auckland Museum (Auckland War Memorial Museum Collections), CC BY 2.0 (Wikimedia Commons) - https://commons.wikimedia.org/wiki/File:Deinacrida_heteracantha_(Giant_weta;_W%C4%93t%C4%81_punga)_(48723527326).jpg

### Pink Fairy Armadillo (Chlamyphorus truncatus)
Taxonomy: Mammalia > Cingulata > Chlamyphoridae > Chlamyphorus > 
A dinner roll that swims through sand and blushes about the whole situation.
- COOL - Size: Smallest armadillo, ~10-12 cm and ~120 g
- WEIRD - Shell: Pink plate attached only along the spine, not fused to the body
- COOL - Blush: Flushes pinker when warm to dump heat, paler to keep it
Photo: Cliff (cliff1066, Flickr), CC BY 2.0 (Wikimedia Commons) - https://commons.wikimedia.org/wiki/File:Pink_Fairy_Armadillo_(Chlamyphorus_truncatus).jpg

### Osedax Zombie Worm (Osedax japonicus)
Taxonomy: Polychaeta > Sabellida > Siboglinidae > Osedax > 
Turned up, ate the loser's skeleton, left with the belt and 600 husbands.
- WEIRD - Anatomy: No mouth, no gut, no stomach, no anus
- GROSS - Diet: Bores into whale bones and dissolves them with acid
- GROSS - Home life: Females carry harems of 600+ microscopic dwarf males
Photo: Syced, CC0 1.0 (Wikimedia Commons) - https://commons.wikimedia.org/wiki/File:Osedax_Japonicus,_at_Enoshima_Aquarium.jpg

It is Saturday, which in this house means the five champions who survived the week get dragged back into the arena to fight each other, and me, and the concept of dignity.

Here is the bracket I have assembled from Monday through Friday: a deep-sea fish with a see-through head, a lizard that squirts blood out of its own eyeballs, a New Zealand bug that weighs as much as a bird, an Argentine armadillo the size of a dinner roll that swims through sand and blushes when it is warm, and a worm with no mouth that dissolves whale skeletons for a living. Cross-taxa, cross-hemisphere, cross-any-line-of-good-taste. Exactly how I like it.

I judge on three things and three things only: how cool, how weird, and how gross. Let's crown a Critter of the Week.

## The bracket, and why nobody is safe

Five winners. One crown. No refunds. I researched each of these little freaks until I had at least two real sources swearing the facts were true, because unlike my opinions, my facts have to hold up.

## Barreleye: the fish that watches you through its own forehead

The barreleye (Macropinna microstoma) has a transparent, fluid-filled dome over the top of its skull, and its actual eyes are two glowing green tubes sitting *inside* that dome. Those green lenses may filter out the sunlight coming straight down so the fish can pick out the faint bioluminescent glow of prey against the dark. The eyes rotate: they point straight up to spot the silhouettes of food drifting overhead, then swivel forward when it is time to eat. And the two dark spots on the front of its face that look exactly like eyes? Those are its nostrils. The real eyes are in the aquarium of its own head.

It lives around 600 to 800 meters down and tops out at about 15 cm. For decades everyone assumed its gaze was locked upward until MBARI filmed a living one and watched the eyes swing around like security cameras. **Cool** rating: absurd. **Weird** rating: it has a windshield.

## Texas horned lizard: the state reptile with a blood cannon

The Texas horned lizard (Phrynosoma cornutum) is the official state reptile of Texas, which means Texas looked at a spiky toad that shoots blood out of its face and said yes, that one, put it on the seal. When a canid predator - a coyote, a fox, your labrador - gets too close, the lizard ruptures tiny vessels around its eyes and fires an aimed stream of its own blood up to five feet. The blood is diet-derived nasty and tastes foul specifically to dogs and their relatives; it does basically nothing to birds, so the lizard saves the trick for the right audience.

What funds this blood budget? Ants. Up to about 70 percent of its diet is harvester ants, picked off a trail one at a time, which is why it has an oversized stomach: ants are terrible calories. It can also puff its body up so its scales stick out and it becomes a mouthful of spikes. **Gross** rating: it weaponized anemia. **Cool** rating: undeniable.

## Wetapunga: the bug that shows up to a fight weighing as much as a sparrow

The wetapunga (Deinacrida heteracantha) is a New Zealand giant weta and one of the heaviest insects on Earth. A gravid female can hit about 35 grams, heavier than an average house sparrow, and captive record-holders have reached around 70. The name roughly translates to god of ugly things, which is the single greatest thing any culture has ever named an animal.

It is flightless, nocturnal, eats leaves, and its body plan has barely changed in about 190 million years, making it older than the tuatara it shares an island with. It survives naturally on exactly one place, Hauturu (Little Barrier Island). When bothered it hisses by rubbing its legs against its abdomen and waves its spiny back legs at you. **Cool** rating: it is a living fossil the size of your palm. **Weird** rating: it breathes through holes in its shell and molts eleven times to get this big.

## Pink fairy armadillo: a dinner roll that swims through dirt and is embarrassed about it

The pink fairy armadillo (Chlamyphorus truncatus) is the smallest armadillo alive, roughly 10 to 12 cm and about 120 grams, endemic to the sandy plains of central Argentina. It is a sand swimmer that spends nearly its whole life underground and is so rarely seen that scientists list it as Data Deficient. Here is the detail that broke me: its pink shell is not fused to its body. It is attached only by a thin membrane along the spine, like a saddle draped over the animal.

And it is pink for a reason. Blood flows into that thin shell to dump heat, which makes it flush pinker when the animal is warm, and drains out to conserve heat, which makes it go pale. It is a mammal that changes color with its mood ring of a back. It also has a flattened rear plate it uses to tamp down soil behind itself as it tunnels, and it almost never survives in captivity. **Cool** rating: it blushes to thermoregulate. **Weird** rating: detachable outerwear.

## Osedax: the boneworm with no mouth and 600 husbands

And then there is the zombie worm (genus Osedax). It has no mouth. No gut. No stomach. No anus. What it has is a root system that it drills into the bones of dead whales that fall to the seafloor, secreting acid through a proton pump to dissolve the bone and release the fats and collagen trapped inside. It cannot digest that on its own, so it farms symbiotic bacteria in its roots to do the eating for it. A mouthless animal that acid-melts a whale skeleton and lets bacteria absorb the soup.

It gets worse, and by worse I mean better. The Osedax you can see are all females. The males are microscopic and live by the dozens to the hundreds *inside her tube* - MBARI has found large females carrying harems of more than 600 dwarf males. She is a mouthless bone-dissolving acid worm and she is also running a studio apartment packed with 600 tiny husbands. A whale skeleton can be stripped clean in as little as a decade. **Gross** rating: off the chart. **Weird** rating: also off the chart.

## Tale of the tape

- Coolest: the barreleye and the wetapunga split this. A glass head versus a 190-million-year-old palm-sized tank.
- Weirdest: the pink fairy armadillo with its detachable blushing saddle, closely stalked by the Osedax.
- Grossest: not close. The lizard squirts blood, but the worm has no mouth, melts bone with acid, and lives with hundreds of husbands.

You know what they say: coolness gets you into the bracket, but grossness wins the belt.

## Winner: Osedax Zombie Worm
Critter of the Week is the **Osedax zombie worm**. Here is my reasoning, such as it is. The barreleye is the coolest and the armadillo is the weirdest, but this crown is decided by total dominance across all three axes, and only one contestant maxes out two of them at once. A mouthless, gutless worm that bores into whale bones, secretes acid to dissolve the skeleton, outsources digestion to bacteria in its roots, and carries a harem of over 600 microscopic males inside her tube is not a runner-up. She showed up, ate the loser's skeleton, and left with the belt and the husbands. The lizard shooting blood from its eyes was the grossest thing here for exactly one round, and then the worm reminded everyone what commitment looks like.

## FAQ

### How does a worm with no mouth actually eat a whale skeleton?
Osedax grows root-like structures into the bone and secretes acid through a proton pump to dissolve it, releasing the fats and collagen locked inside. It cannot digest that directly, so symbiotic bacteria living in the roots break it down and the worm absorbs the nutrients. No mouth, no gut, no problem.

### Does the Texas horned lizard really squirt blood from its eyes, and does it hurt it?
Yes. It ruptures small blood vessels around its eyes and fires an aimed stream up to about five feet, mainly at canids like coyotes and dogs, because the blood is diet-derived and tastes foul to them. It costs the lizard a real amount of blood per squirt, so it is a defense of last resort, not a party trick.

### Why is the pink fairy armadillo pink?
Its thin dorsal shell is packed with blood vessels used for temperature control. When the animal is warm, blood flows into the shell to shed heat and it flushes pinker; when it needs to conserve heat, blood drains away and the shell looks paler. The color is basically a thermostat you can see.

### Is the wetapunga really heavier than a bird?
A gravid female wetapunga can weigh around 35 grams, heavier than an average house sparrow, and captive record specimens have reached roughly 70 grams. It is one of the heaviest insects on the planet, and it cannot fly, which frankly is for the best.

## Sources
- Barreleye Fish (Macropinna microstoma): https://www.mbari.org/animal/barreleye-fish/
- Researchers solve mystery of deep-sea fish with tubular eyes and transparent head: https://www.mbari.org/news/researchers-solve-mystery-of-deep-sea-fish-with-tubular-eyes-and-transparent-head/
- Texas Horned Lizard (Phrynosoma cornutum): https://tpwd.texas.gov/huntwild/wild/species/thlizard/
- Canid Elicitation of Blood-Squirting in a Horned Lizard (Phrynosoma cornutum): https://www.researchgate.net/publication/270466753
- Osedax Studies: https://www.mbari.org/project/osedax-studies/
- Osedax: Bone-Eating Marine Worms with Dwarf Males: https://www.science.org/doi/abs/10.1126/science.1098650
- Giant weta / wetapunga: https://www.doc.govt.nz/nature/native-animals/invertebrates/weta/giant-weta-wetapunga/
- Wetapunga: https://www.aucklandzoo.co.nz/animals/weta-punga
- Chlamyphorus truncatus (pink fairy armadillo): https://animaldiversity.org/accounts/Chlamyphorus_truncatus/
- Husbandry of a pink fairy armadillo (Chlamyphorus truncatus): https://onlinelibrary.wiley.com/doi/abs/10.1002/zoo.20334

Tags: Actinopterygii, Reptilia, Polychaeta, Insecta, Mammalia, champion-of-the-week, weekend-special, deep-sea, totally-random

Canonical: https://lamalo.blog/champion-of-the-week-barreleye-lizard-osedax-wetapunga-armadillo