A couple of years ago, I wrote about fungus-farming ants. These ants are a famous example of non-human animals farming, but they're hardly alone; for example, some termites, ambrosia beetles, damselfish, and snails have also been known to farm. Late last year, a research team in Brazil added a social bee to the ranks of farming animals.

The team was researching the stingless bee Scaptotrigona depilis when they noticed a white fungus growing on the inside of the wax cells where larva are reared. Their curiosity piqued, they checked 30 colonies and found the fungus in all of them. The fungus starts growing around the same time as the egg hatches. During the first three days of the larva's life, the fungus grows inwards over the larval food; after the third day, the amount of fungus drops, disappearing two days later.

Using time-lapse images, the researchers saw that the larva cut the fungus with its mandibles as it grew. When the researchers tried growing larva in cells without the fungus, only 8% of them survived, and the larval food in those cells "smelled bad and showed other signs of spoilage such as stickiness". The researchers speculated that the fungus may help preserve the larva's food, but a test against the bacteria Escherichia coli and Staphylococcus aureus didn't support their hypothesis, though it didn't disprove it, either. While the fungus wasn't effective against these bacteria, it might have an effect on other pathogens which are specific to S. depilis.

The researchers found the fungus in the building material used by the bees, a mixture of wax and plant resins called cerumen. Although the fungus was in cerumen samples from throughout the nest, it only grows when the cerumen is used to build brood cells, perhaps because it needs contact with the larval food to grow. The fact that the fungus is in the cerumen means that the workers take it with them when they go to build a new colony, which is unusual. In fungus-farming ants and some termites, the reproductive adults take fungal spores with them when they set off to found a new colony.

According to the paper, this is the first known fungus-growing bee, despite the fact that bees have been extensively studied and other social insects have been known to grow fungi. Perhaps fungus-growing is rare among bees, or maybe we just haven't thought to look for it. To me, this a wonderful reminder of how much we still have to learn — all the wonderful mysteries just out of sight in the mundane, tucked under something we've forgotten to see, made invisible by familiarity. I think we can all afford to slow down and learn to look without expectation; it's a habit I aspire to, and one I hope to inspire in tohers.

Ref
Menezes, et al. A Brazilian Social Bee Must Cultivate Fungus to Survive. Current Biology 25:2851-2855. (2015) doi:10.1016/j.cub.2015.09.028

Image credits
The image is adapted from Figure 1 in the paper.

A version of this article was originally published in The Scorpion and the Frog. To see the original, go 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.

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!

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!

References:

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/z04-174

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

Image: The jellyfish life cycle by Zina Deretsky at the National Science Foundation. Image available at Wikimedia Commons.