The more we learn about the world, the weirder it seems. Physics has turned out to be weirder than people could have imagined, especially with increased understanding of quantum mechanics. Our concept of time is bizarre. Even mathematics, which should really just behave itself, doesn’t seem to want to cooperate.
It shouldn’t be a surprise that there’s plenty of weirdness in biology as well. The closer we look, the more we realise there’s so much we don’t know about the organisms we share our planet with. For a taster, here are 6 of our favourite bizarre biology facts.
1. Some mammals can detect magnetic fields
Some organisms see the world very differently than we do. Magnetoreception is a remarkable sense that lets organisms detect magnetic fields in order to understand their location, their altitude, or even their current direction. These animals include bacteria orienting along magnetic fields; nematode worms using the Earth’s magnetic fields to move up or down through soil; birds using magnetic fields for migration; and some mammals even seem to be able to detect magnetism.
Have you ever seen foxes jump onto small prey? It’s called a mouse pounce. When red foxes do it, they tend to jump in a specific direction. In one study of 84 foxes, 74% of successful attacks happened when the foxes were facing about 20 degrees clockwise of magnetic North. The favoured hypothesis is that the magnetic fields are used as a rangefinder, allowing the foxes to accurately judge the distance to jump. The combination of the magnetic field with the sound of the mouse lets them calculate the angle and distance to leap.
Biologists can explain how some organisms like bacteria and worms detect magnetism but it’s more difficult to verify in mammals. It’s not known where in the brain this information would be processed but there is a candidate for the protein involved in detecting the fields themselves. Cryptochrome is found in the eye and has been shown to respond to magnetism. Us humans use the protein too but there’s no evidence we can read magnetic fields. Perhaps our ancient ancestors could.
2. Some organisms are “biologically immortal”
No living thing is truly immortal. Live long enough and something will eat you or your habitat will be destroyed. Even if we stay safe and have a stable environment, we’ll eventually die of senescence (biological ageing) but not all organisms do. Ancient trees that are thousands of years old look beat up but that’s because they see harsh winters, damage from animals, and the odd lightning strike now and then. But over those thousands of years their DNA has been kept in good shape, with no increase in mutation rates despite growing old. For them, it’s the environment that’s the killer.
There are countless biologically immortal species but the most famous example is the immortal jellyfish, Turritopsis dohrnii. Compared to a lot of species, our lives are quite boring. We’re born, we get bigger, and then we die. Not very varied is it? The immortal jellyfish starts life as a tiny larva but it doesn’t simply grow into an adult like we do. Instead, it has a complex life history where it lives for while as a polyp on a hard surface that eventually gives rise to an adult jellyfish. Amazingly, these adult jellyfish can revert back from being a sexually mature adult to being an immature polyp and begin the process again.
It’s a technicality, because the jellyfish will be eaten or become diseases given enough time, but they can live forever by growing up over and over again.
3. A third of us are infected by a cat-loving brain parasite
Toxoplasma gondii is a brain parasite that reproduces exceptionally well inside the intestines of cats. Outside of cats it doesn’t do as well but is still able to infect many other animals, ourselves included. When cats poop out the parasites, they sometimes get into other animals like rats. Researchers have found that the parasite hijacks immune cells in the rat’s stomach and uses it as a getaway vehicle to enter the brain undetected. Once there it causes changes in the rat’s behaviour so that it no longer fears the smell of cats. These rats are more likely to be eaten by a cat and the parasites return to where they reproduce best: the cat’s intestines.
Shockingly, the parasite is estimated to have infected a third to a half of the global human population. The numbers vary between countries. There are approximately 60 million carriers in the US. In France, 88% of the population is infected. In Korea only 4.3% are infected. The NHS estimates that a third of the UK population pick up the infection. The reason most people don’t know about it is that it’s harmless for people unless they have weakened immune systems.
It can modify the behaviour of animals to make them more likely to come into contact with cats. Could “crazy cat lady” be caused by a brain parasite? Does toxoplasmosis explain the internet’s feline obsession? We think that’s rather unlikely but then maybe it’s just the parasites talking.
4. Tardigrades can survive the vacuum of space
Tardigrades, or water bears, are tough little creatures that can survive extreme conditions. They look like microscopic, 8-legged bears but they’re invertebrates not too distantly related to arthropods. Here on Earth they’ve already been put under every grueling test you can imagine: extreme pressures, huge radiation doses, and being completely dried out and frozen for decades with no food or water before springing back to life. They do this by entering a state of cryptobiosis where all metabolic processes are stopped. They don’t eat, grow, reproduce, or even repair their DNA. When conditions are safe again, they transform back into their normal selves munching away on food and making babies.
The European Space Agency (ESA) sent dried up tardigrades into space in 2007 on the FOTON-M3 mission. The tardigrades were exposed to the vacuum of space for 10 days before the satellite returned them to Earth. Some tardigrades were shielded from the Sun’s radiation, which is far more intense than anything we’re used to on the Earth’s surface. Others were exposed to solar winds and all faced the freezing, oxygen-free environment of space. The tardigrades exposed to more radiation were damaged but all of them coped fine with the cold vacuum of outer space and many went on to reproduce back on Earth.
Tardigrades aren’t special though. Some of us at Gadgette have a similar ability of cocooning ourselves in and shutting down during extreme conditions.
5. Parrots are more than mindless mimics
Research in the last couple of decades has revealed that corvids (crows and ravens) are much smarter than we gave them credit for. We now know then can solve cause-and-effect problems faster than children. Crows and ravens build and use tools; solve complex puzzles; recognise individual humans; and even seem to have fun.
Corvids seem to be the best problem solvers so they’re stealing a lot of the limelight. Other birds are also clearly more intelligent than we originally thought. Nobody can deny that it’s impressive when a parrot perfectly mimics human voices but it’s just a trick, right? You might think of them as brainless copycats but they understand language a lot better than you might expect.
Parrots can solve linguistic problems better than small children and make logical leaps based on words alone. Parrots can understand zero (or at least the concept of absence) and use words like “different” and “same” correctly. Scientists who study parrot intelligence claim they have an emotional intelligence that exceeds toddlers. Alex the parrot was regarded as the most intelligent studied so far and his researchers believed he was as intelligent as a 5-year-old human child.
6. Some insects are more closely related to their siblings than their own parents
Because we get half of our genetic material from our mother and half from our father, we’re obviously closely related to them. Cousins and aunties though? Not quite as close. For us, parents are as close as it gets but let’s not forget siblings. Our brothers and sisters are just as closely related to us as our parents. To biologists, we’re 50% related to our parents or siblings. Evolutionary biologist J. B. S. Haldane was once asked if he would give his life to save a drowning brother and he responded, “No, but I would to save two brothers or eight cousins.”
There are some animals that can be more closely related to their siblings than their own parents. It seems absurd to think that the individuals that reproduced to create you could be anything but your closest relatives but it’s because of an interesting phenomena called haplodiploidy. In humans, we all have two sets of chromosomes and that makes us diploid. But in haplodiploid species, males develop from unfertilised haploid (one set of chromosomes) eggs and females from diploid eggs. This system is used in bees, ants, and wasps, where males have half the number of chromosomes as females.
The fascinating thing about this sex-determination system is that it allows the evolution of eusociality. If you think about bees, wasps, and ants, they all share the remarkable ability to create social colonies and to have individuals work to look after a queen. This is explained because the queen’s female offspring will be 50% related to her but 75% related to each other.
Natural selection is about the survival of genes and we’re taught to think about individuals passing on their genetic information. Yet in these eusocial-insect colonies, individuals often forgo reproduction in order to work for the queen and help her reproduce. That seems to fly in the face of natural selection and genetics but makes sense when you consider the haplodiploidy. The female workers are more closely related to their sisters than their own mother. The best way for them to have more of their own genetic material reproduced is to create more siblings, so it makes sense to help the queen. If a female produces offspring, they’re only 50% related to her (just like human babies to their mothers), but if the females help the queen reproduce then they’ll have more sisters that are 75% related.
If you think all that is weird, think about how haplodiploidy means that males can have no father and no sons, yet can have a grandfather and grandsons.
Main image via Flickr/Macroscopic Solutions distributed under CC BY-NC 2.0