Dead and alive: a rotifer having transformed into a tun or xerosome
An animal which
revives after death confounds our most cherished ideas and becomes an object
no less interesting to the naturalist than to the the philosopher. - Lazzaro Spallanzani
I.
If I've said it once, I've said it a million times: Being alive is only a very rare and unusual way of being dead [1].
And if I ever have enough money to establish my own thanatological research centre in Death Valley, then this will be the phrase engraved in stone above the entrance.
No surprises then that a recent article by the freelance science writer Phil Jaekl on the Nautilus website should grab my interest ... [2]
II.
Entitled 'The Animals That Exist Between Life and Death', it discussed those astonishing creatures who inhabit the unexplored microcosmos and are capable of entering a sort of zombified state that is neither one thing nor the other, much to the horror of those who like distinctions to be clear cut and permanent: either this, or that; dead or alive.
These animalcules, as they were originally known [3], are now referred to (less charmingly) as rotifers; a Neo-Latin term meaning wheel-bearer and which refers to the distinctive ciliated appendage called a corona that they possess around their mouths and use to assist with both feeding and movement.
Found living in watery environments all over the world - from the great oceans to small puddles - rotifers have perfected a rather neat trick that they perform when their aqueous environment dries up; they contract into a survival structure known as a xerosome which enables them to endure harsh, dry conditions by entering a
(metabolically inactive) state of anhydrobiosis.
And they can remain as tuns, as they're known, for a significantly extended period of time - we're talking many years here, not just a few days or weeks [4] - in the most extreme conditions, as they patiently await the chance to reanimate; just add water and hey presto! they'll be swimming around once more as if nothing had happened [5].
As Jaekl reminds us, this presents a philosophical paradox beyond the biological questions raised: "Were the animals technically dead? Were they, in tun form, actually still alive but dormant, like a mammal in hibernation? Or were they in some kind of liminal, in-between state?" [6]
As the underlying assumption is that organisms are either alive or dead, "the paradox lies in maintaining the possibility of such a binary proposition in the face of rotifers and other extremophiles that seem to occupy such a third state as they await reanimation" [7].
Jaekl continues:
"Even as microbiologists have been working for centuries now to piece together how rotifers and several other animal species survive desiccation and other extreme conditions, philosophers are still grappling with the idea that life and death may not be the only states of being in which organisms can exist." [8]
II.
It wasn't until the mid-twentieth century, thanks to the work of Russian-born British biologist David Keilin, that science really began to understand how rotifers and other extremophiles were able to survive desiccation via physiological dormancy or cryptobiosis, i.e., a state in which there are no visible signs of life and metabolic activity is undetectable [9].
And, in part, this relates to the fact that the appear to have incorporated DNA from yeast, fungi, and plants, so that around 10% of their genome isn't actually animal. In other words, not only do they curdle the alive/dead dichotomy, but they fuck with the animal/plant binary making them the scandal of evolution - just one more reason to love 'em!
More: it seems that not only do rotifers not age whilst in a deadened state, they wake up younger! That's not something that even Sleeping Beauty managed to do. And reanimated rotifers also tend to live longer and be more reproductively active than those rotifers who never undergo desiccation; i.e., being dead for a while is actually beneficial [10].
Notes
[1] I am of course paraphrasing Nietzsche; see The Gay Science (III. 109) where he writes: "Let us beware of saying that death is opposed to life. The living is merely a type of what is dead, and a very rare type." English trans. by Walter Kaufmann (Vintage Books, 1974), p. 168.
[2] Philip Jaekl, 'The Animals That Exist Between Life and Death', Nautilus (16 April 2025): click here. This article comes with images by someone I so much wanted to be called Mr Hyde; unfortuatey, he's named Robert Berdan.
Readers interested in this post might also be interested in Jaekl's latest book; Out Cold: A
Chilling Descent into the Macabre, Controversial, Lifesaving History of
Hypothermia (Public Affairs, 2021).
[3] Animalcule - Latin for 'little animal' - is an archaic term for microscopic organisms coined by 17th-century Dutch scientist Antonie van Leeuwenhoek to refer to the creatures he observed in rainwater.
[4] In June 2021, biologists reported the restoration of a class of rotifers found in freshwater habitats all over the world known as bdelloids (of which there are over 450 identified species), after they had been frozen for c. 24,000 years in the Siberian permafrost.
Of course, rotifers are not the only creatures who have mastered the art of being dead/alive; tardigrades, or so-called water bears, can survive not only desiccation but also
radiation, extreme temperatures, and even the vacuum of outer space. Collectively, animals of this kind are known as extremophiles.
[5] Just to be clear on this point: I'm not saying that rehydrated rotifers rejoin the world of the living completely unscathed:
"During desiccation they undergo considerable chromosomal breakage. Some
regions of their DNA are shattered. But when water returns, potentially
after years, the organisms are still able to begin moving again within
about five to 10 minutes. Within about half an hour, they will have
restructured their DNA as it was. To achieve their apparent
resurrection, rotifers rely heavily on advanced DNA repair mechanisms." - Philip Jaekl, 'The Animals That Exist Between Life and Death', op. cit.
[6] Ibid.
[7] Ibid.
[8] Ibid.
[9] Should we view cryptobiosis as a unique state of being between life and death? I'm not sure and some theorists, such as Thomas Lemke, think it would be helpful to drop this term altogether as it "does not account sufficiently for the processual and relational dimensions of ametabolic life" and also implies the existence of some hidden or latent form of life.
Lemke prefers the related by different concept of limbiosis, i.e., suspended life which, in his view, better addresses the liminal state of biological organisation and emphasises the liminality of the neither-nor life and death. See his essay 'Conceptualising Suspended Life: From Latency to Liminality', in Theory, Culture and Society 40 (6): 69-86 (2023). The line quoted from above is found in the abstract to this essay.
[10] Something that Jesus discovered; certainly in the reimagining of his death and resurrection by D. H. Lawence in his short novel The Escaped Cock (1929).
