Ten biology facts and the source pages behind them

These are ten biology facts with sources attached: water bears that dry into a ball, a red waterfall in Antarctica, a fern with a giant genome and the bacteria you carry. I opened each source page, copied the sentence that carries the claim, and marked where the headline says more than the page does. [1]

The science library holds more than these ten. I kept to living things and the tools used to study them.

What survives where nothing should

A tardigrade dries itself into a ball

The library says a tardigrade survives drought by shrivelling into a ball called a tun. The Tardigrade article describes the move: "by drawing their legs in and forming a desiccated cyst, the cryptobiotic 'tun' state, where no metabolic activity takes place" [1]. The library calls it a near-standstill, which is the more careful word. The article also names the protection: tardigrade specific proteins that "may also form a glass-like matrix" around the inside of the cell [1].

Why the source matters: it says "may". The glass idea is a leading explanation, not a settled one.

Dried tardigrades spent ten days in open space

In 2007, dried tardigrades rode the FOTON-M3 mission and were exposed to space for ten days. The article's account is blunt about what hurt them: "Vacuum exposure alone had no significant effect on any metric" [1], but vacuum combined with ultraviolet light killed many. Full solar ultraviolet left only three survivors of one species [1].

Why the source matters: the headline's "survived space" is true for the shielded group only. Sunlight was the killer, and the article does not repeat the library's "first animals" claim, so I could not check that part there.

Microbes live under a glacier with no oxygen

Blood Falls pours rust-red brine from Taylor Glacier, and the library says the lake behind it was sealed for over a million years. The article gives a range from a 2009 study: "the now-inaccessible subglacial pool was sealed off 1.5 to 2 million years ago" [2]. The red is iron oxide, not algae, and the brine sampled through a crack was oxygen-free [2].

Why the source matters: it turns "over a million" into a number with a study behind it.

The record holders

The largest genome belongs to a small fork fern

The library's genome fact names a fern from New Caledonia. The Tmesipteris article I fetched first says nothing about genome size, so I went to the record itself. Guinness World Records says the largest genome measured "is 160.45 billion base pairs (Gbp, or gigabases), for the Tmesipteris oblanceolata fork fern" [3]. That is more than 50 times the DNA in a human cell nucleus, and the paper appeared in iScience on 31 May 2024 [3].

Why the source matters: the record is for organisms "assessed to date using best-practice methods" [3]. Bigger genomes may exist that nobody has measured properly.

One honey fungus covers a patch of Oregon

The library calls it the largest living thing on Earth, at almost 4 square miles. The Armillaria ostoyae article is more guarded, calling the Malheur National Forest specimen "one of the largest organisms on Earth, if not the largest living organism on Earth, by mass, area, and volume" [4]. It gives 3.5 square miles and an age estimate of some 8,000 years [4].

Why the source matters: the same article says a Posidonia australis colony on the Australian seabed rivals it by area, so "largest" depends on what you count as one organism [4].

Tools that read the body

A doctor's dyes led to the magic bullet

The library's Ehrlich fact is about a German physician who saw that dyes could pick out one kind of cell. Paul Ehrlich's article traces the idea from staining to medicine: "Ehrlich reasoned that if a compound could be made that selectively targeted a disease-causing organism" [5], a toxin could ride along with it. His lab found Compound 606 in 1909, and it went on sale as Salvarsan, a syphilis treatment, at the end of 1910 [5].

Why the source matters: it shows the step from a stained slide to a drug was a deliberate guess, tested compound by compound.

Bomb carbon dates the cells in your brain

Above-ground nuclear tests nearly doubled the carbon-14 in the air before the 1963 test ban, and every cell built since carries that tag [6]. The library uses it to say most cortex neurons are as old as their owner. The Bomb pulse article, describing Kirsty Spalding's work, says "neuronal cells in some brain regions are essentially static and do not regenerate during life" [6].

Why the source matters: "some brain regions" is narrower than the headline. The same work found about 10% of fat cells are renewed each year [6].

The bacteria in and around you

You are roughly half bacterial cells

The library says you are only about half human. The Human microbiome article gives the counts: "The number of bacterial cells in the human body is estimated to be around 38 trillion" [7], against an estimate of 30 to 40 trillion human cells [7].

Why the source matters: "half" is a count of cells, and both counts are estimates. The same article puts bacterial genes at about 2 million, 100 times the human count [7].

You leave a cloud of bacteria behind you

The library says your personal cloud of bacteria can identify you from the air of a room you have left. I read the Human microbiome article for this and did not find the claim there. I have not fetched the study behind it, so it stays on this list as the library states it, and its fact page carries the source.

Peanuts grow underground and are not nuts

The peanut fact is the one that sounds like trivia and holds up best. The Peanut article says "Peanut fruits develop underground, an unusual feature known as geocarpy." [8] After fertilisation, a stalk called a peg grows down and carries the young fruit into the soil [8]. The plant is in the pea family, and the article says plainly: "Botanically they are not nuts" [8].

Questions

Which of these biology facts has the weakest source?

The personal bacteria cloud. I read the Human microbiome article and did not find the claim, and I have not fetched the study the library relies on. The neuron fact comes next: the Bomb pulse article says neurons in some brain regions do not regenerate, which is narrower than saying most cortex neurons are as old as you [6].

Can tardigrades really survive in space?

Some of them, under shielding. On the 2007 FOTON-M3 flight, vacuum alone had no significant effect on dried tardigrades, but vacuum with ultraviolet light killed many, and full solar ultraviolet left only three survivors of one species [1]. So they cope with the emptiness of space far better than with unfiltered sunlight.

Is the honey fungus the largest living thing on Earth?

It may be, depending on how you count. The Oregon specimen covers about 3.5 square miles and may weigh as much as 35,000 tons, but its article calls it one of the largest organisms, and notes a Posidonia australis colony on the Australian seabed that rivals it by area [4]. If a connected clone counts as one organism, it is a strong contender.