When The Going Gets Tough, The Tough Become Babies

Today I am giving new young life to a post from 2012. You can find the original here.

We celebrate the New Year as a time of rebirth, renewal, and do-overs. We join gyms, swear off our bad habits, and promise to be better people. This is especially true for those of us that have had a rough 2015... Our 2016-version-of-us has got to be better, right? But what if you could get a real do-over? What if you could be a kid again, grow up again, and become a brand new person? As far-fetched as it may sound, some animals do exactly that.

Cnidarians (the "C" is silent) are a huge group of aquatic animals that includes jellyfish, corals, and anemones (like the one Nemo lived in - Yeah, that tentacled home was a living animal). They are named after prickly plants known as nettles, or cnides in Greek, and if you touch one you will quickly know why. Cnidarians, armed with stinging cells called nematocysts, sting at the slightest touch.

Jellyfish make up many of the cnidarian species, and they have been found in every ocean and at every depth. Some even live in freshwater. The "typical" jellyfish life cycle starts when eggs and sperm are released into the water and find one another. When they do, they form larvae, which you can think of as baby jellyfish. The larvae sink and settle on a hard surface, where they mature into polyps. These polyps are jellyfish in a juvenile stage. The polyps elongate and begin to bud off adult medusa, which are the bell-shaped blobs with tentacles that most of us think of when we think of a jellyfish. Medusa mature to become reproductive adult jellyfish.


The jellyfish life cycle by Zina Deretsky at the National Science Foundation (NSF). Image available at Wikimedia.

Larval and polyp jellyfish are much more resistant to harsh conditions then are medusa jellyfish. When life gets hard for a jellyfish, perhaps because of starvation, physical damage, temperature changes or salinity changes, those that are in the larval or polyp stages can often shrink and rest in a hibernation-like state while they wait for more favorable conditions. But in some species, young adult medusa can even regress back to the juvenile polyp stage. By reverting back to a juvenile stage, they have more protection from the challenging world around them.

In most cases, this reversal to a juvenile state can only happen in young medusa that have not yet developed their gonads. Thus, the onset of sexual reproduction (puberty, if you will) might be regarded as the point of no return in development. However, one species, called the immortal jellyfish, has shown that this rule can be broken.

As an adult medusa, the immortal jellyfish is a pea-sized jellyfish with a round bell, bright red stomach and anywhere from 8 to 90 tentacles. It is currently the only known animal that can regress from a fully reproductively mature adult into a juvenile polyp. If exposed to dangerous conditions, immortal jellyfish medusae completely reduce all of their medusa-specific organs and tissues and develop new polyp-specific tissues, essentially becoming kids again!

This figure from the Piraino et al. 2004 paper at the Canadian Journal of Zoology shows the life stages of the immortal jellyfish. The adult medusa is in panel (a). Panels (b) and (c) show the medusa tranforming to a ball-like blob as it reverts to a juvenile stage. The green stain in these panels shows the cells initiating this transformation. Panel (d) shows the remnant of a medussa, and the black arrow shows the stalk that is common in the polyp stage. Panel (e) shows the resulting juvenile polyp.

But wait! It gets better! Theoretically, if an animal can revert to a juvenile stage at any point in its adult life, it could attain immortality. But if that were true, they would have the classic immortality problem: These animals would reach such high populations they would saturate the world's oceans...And this may actually be happening.

Immortal jellyfish are thought to originally be from the Caribbean, but they have since been discovered worldwide and their populations seem to be growing. Likely, they are hitching rides in the ballast water that is sucked into cargo ships to provide stability. If this is true, the immortal jellyfish polyps could be attaching to the ships' hulls and settling in for a long voyage to a new home.

We don't yet know if the immortal jellyfish are actually immortal, but it is fun to consider that they might be (although they can still be killed by predators or viruses, so they're not invincible). And we can take inspiration from them: When the going gets tough, try reverting to your more resilient juvenile self, but be thankful you don't have to go through middle school again!

Happy New Year!

To learn more, check these out:

1. Piraino, S., De Vito, D., Schmich, J., Bouillon, J., & Boero, F. (2004). Reverse development in Cnidaria Canadian Journal of Zoology, 82 (11), 1748-1754 DOI: 10.1139/z04-174vv

2. Miglietta, M., & Lessios, H. (2008). A silent invasion Biological Invasions, 11 (4), 825-834 DOI: 10.1007/s10530-008-9296-0

Our Most Popular Posts of 2015

To celebrate the end of the year, I compiled a list of The Scorpion and the Frog's most popular posts of 2015. If you missed them, check them out here:

#5. Gut Feelings explains new research that shows that the microorganisms living in our guts can affect our behavior in mysterious ways.

#4. In Vole Pee: An Epiphany, Nate Kueffer talks about how birds of prey use ultraviolet vision to see pee-trails of their prey.

#3. Prepare to be amazed! Enjoy The Weirdest Animals on Earth: 12 Amazing Facts About Octopuses.

#2. Rachael Pahl tells us about some crazy bug sex in The Bed Bug’s Piercing Penis.

#1. In The Beginnings of Jurassic Park: Dinosaur Blood Discovered?, Sam Vold contemplates the real science behind Jurassic Park.

There have been some fascinating animal stories by many great science writers. Here's to many more stories in 2016! Happy New Year!

Caught in My Web: All About Dogs

Image by Luc Viatour at Wikimedia.

For this edition of Caught in My Web, we celebrate our wonderful canine companions.

1. Nina Golgowski at HuffPost Science explains research that shows that dogs give treats to their doggy friends, but not to doggy strangers.

2. Rafael Mantesso's wife left him and took everything but the dog and the empty white apartment. Rafael found inspiration in his predicament and created some of the most wonderful photos ever! Check them out here.

3. Let puppies teach you about complexity theory in this TED talk by Nicolas Perony.

4. Virginia Hughes at National Geographic shares research that shows that dog brains process voice information similarly to our own.

5. And just for fun, here is Bella the dog singing “Jingle Bells”:

Why Are Cats Scared of Cucumbers?

Have you seen the video of cats’ terrified responses to cucumbers? No?! Then check this out:

This hilarious video has led many people to try this on their own cats… to varying degrees of success. And it has led to some curious questions: Why are these cats so terrified of a cucumber? And why isn’t my cat?

The fear of something specific (like a cucumber) can either be innate (as in, you’re born with it) or learned. For many animal species, it would make sense to be born with a natural fear of something that can kill you the first time you encounter it, like a steep drop, being submerged under water, or a venomous snake. Some of these things can be so dangerous that an animal with a fear of anything that even resembles it may have a higher chance of surviving long enough to produce its own fearful babies some day. So maybe these cats have an innate fear of snakes that has caused them to respond in this hilarious way to anything that resembles a snake… like a cucumber?

But if cats have an innate fear of snakes, why don’t they all respond to cucumbers this way?

Sometimes fears appear to be innate, when they are actually learned. For example, in 2009, researchers Judy DeLoache and Vanessa LoBue at the University of Virginia explored whether the fear of snakes is innate in human babies with a series of three experiments.

In the first experiment, Judy and Vanessa showed 9- and 10-month old babies silent films of snakes and other animals and they measured how long the babies looked at each type of film. Presumably, a baby will be more vigilant of and spend more time looking at something they are scared of. They found that the babies responded exactly the same towards the snake films than to the films of other animals.

Next, the experimenters showed the babies the films of either a snake or another animal again. However, this time they played the audio of a person sounding either happy or frightened along with the video. The babies looked at the non-snake animal videos the same amount regardless of whether the audio sounded happy or scared. However, the babies looked at the snake videos longer if the audio sounded scared than if the audio sounded happy.

In the third experiment, the experimenters repeated this pairing of audio with visuals, but this time they used still pictures of snakes and non-snake animals instead of videos. This time, the babies did not react differently to the snake or non-snake animal pictures depending on if the audio sounded happy or scared.

This shows that, at least for people, we don’t have an innate fear of snakes, but we do have an innate tendency to develop a fear of snakes if we are exposed to the right combination of hearing someone being afraid and seeing a moving snake. In other words, some fears are more contagious than others. And this isn’t just true for people: a study of rhesus monkeys found that baby monkeys raised by parents that were afraid of snakes only developed a fear of snakes themselves if they observed their parents acting fearful in the presence of a real or toy snake. So perhaps, the cats in this cucumber video saw or heard someone being fearful of something cucumber-like (or snake-like) when they were young... Or maybe they were just surprised by something sneaking up on them while they were eating.

In any case, don’t be too bummed if this hasn’t worked on your cat… Maybe try it on your friends instead!

Want to know more? Check these out:

DeLoache, J., & LoBue, V. (2009). The narrow fellow in the grass: human infants associate snakes and fear Developmental Science, 12 (1), 201-207 DOI: 10.1111/j.1467-7687.2008.00753.x

Mineka, S., Davidson, M., Cook, M., & Keir, R. (1984). Observational conditioning of snake fear in rhesus monkeys. Journal of Abnormal Psychology, 93 (4), 355-372 DOI: 10.1037/0021-843X.93.4.355

Are GMO Fish Safe for the Environment?

Photo of an Atlantic salmon by Hans-Petter Fjeld, licensed under
the Creative Commons Attribution ShareAlike 3.0 License and
available at Wikimedia Commons.

The U.S. Food and Drug Administration (FDA) recently approved the first genetically engineered animal for food consumption, AquAdvantage Salmon, a salmon strain developed 25 years ago by AquaBounty Technologies. The FDA determined that this salmon strain is as safe to eat and as nutritious as other wild-caught or farm-raised Atlantic salmon and they have provided strict guidelines as to where and how these fish can be farmed (authorizing only two specific facilities, one in Canada and one in Panama, to breed and raise them). These fish will likely soon be in our grocery stores and restaurants, despite the resistance of many environmental and food-safety groups as well as skeptical grocery chains and citizens. What exactly are these animals and do they pose a threat to our environment?

Today at Accumulating Glitches, I talk about genetic engineering, GMOs, and what scientists think about whether AquAdvantage Salmon pose a risk to our environment. Check out the whole article here.