2872: Hydrothermal Vents

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Hydrothermal Vents
Benthic Santas weren't even discovered until the 1970s, but many scientists now believe Christmas may have originally developed around hydrothermal vents and only later migrated to the surface.
Title text: Benthic Santas weren't even discovered until the 1970s, but many scientists now believe Christmas may have originally developed around hydrothermal vents and only later migrated to the surface.


This Christmas comic was released on Christmas Day 2023, in the morning (at least in Randall's timezone in Boston). It is the second Christmas comic using Facts, an Ocean Fact in this comic. The first of these was released six years earlier, also on Christmas Day in comic 1933: Santa Facts. In the world above the surface of the sea, Santa Claus had just finished his annual trip around the world when this comic was posted.

The comic claims that there are "benthic Santas", meaning Santas that deliver gifts to the seafloor. The joke here is that all Santas may be drawn to go down chimneys by their very existence, and that hydrothermal vents have evolved to trick undersea Santa into entering them, believing they were real chimneys, and thus getting killed and digested by the vents as seen in the comic. This is not an entirely unknown digestive mechanism, although the depicted version goes beyond all known biological processes. This comic is one of the darker-themed Christmas comics, compared to the usual merry xmas comics.

There are many things that are very strange mentioned. There is little to no evidence that actual humans live down deep in the sea, and fish and other undersea creatures are unlikely to know what "Santa" is or understand the concept of Christmas, so it is unclear what the exact ecological niche of "benthic Santas" might be. The comic shows the remains of several "Santas", suggesting that there may be multiple members of this 'Santa' species, in contrast to some assertions in the literature that there is only one (although this proliferation might also help explain the many Santas who appear on street corners, shopping malls, etc.). It is also possible that there is just one extant specimen Santa at any time (perhaps or perhaps not of the specifically subsea variety), whose death invokes the spontaneous appearance of a replacement, or causes (clauses?) another transformation into the 'santa' form, through socially-mediated dimorphism, from a population of initially non-santaform individuals.

The title text may be referring to abiogenesis, the origin of life. It was thought non-living matter combined into living cells in shallow water through the energy supplied from the sun and lightning. At least, amino acids can be synthesized this way, as proven by the Miller–Urey experiment. A new explanation places the origin of life on hydrothermal vents, as they are rich in chemicals, and rocks there serve as catalysts, with energy coming from earth's heat. Either way, forms of life are known to migrate between environments to fill new (or vacated) niches, after having been established in another. The current residents of 'black smokers' include creatures (like shrimps, worms and crabs) that are known elsewhere, but could theoretically repopulate the surface if there were ever further mass extinctions across the uppermost layers of the real world, as there have been in prior times.

The 1970s timeframe likely refers to the discovery in 1977 of hydrothermal vent ecosystems near the Galapagos Rift, which formed the basis of this new theory of abiogenesis. By suggesting that the "benthic Santas" were part of this discovery, the comic implies that a key aspect of Christmas folklore might also have its roots in these deep-sea ecosystems.

This was the second time in three years that Santa is killed in Randall's Christmas comics, the first being 2559: December 25th Launch. Before this he has only killed Santa back in 2008 in the 2008 Christmas Special.


[An undersea landscape is shown. A rock formation goes up from the the middle part op the bottom of the panel. The top of the formation has five "hot-smoker" chimneys of different heights, almost like a hand with the thumb to the right, but the middle finger being the shortest and the "index finger" being somewhat longer than all the others. From all five chimneys thick gray smoke is emitted. The smoke rises almost vertically to start from all five, and the four to the left have their smoke combine rather early and it bulges to the left. The rightmost chimney's smoke bends to the right and only merges with the combined smoke from the others at the top right. Below the chimneys their interior in the rock formation is indicated with dotted lines and the inside of these chimneys are thus displayed. At the bottom all five merge into a large cavity (shown with dotted lines) inside the rock formation. In this cavity there is a liquid in which several items float around, most notably two Santa Claus hats and two large bones surrounded by five smaller blobs of material and several smaller specks. On the outside on the rock formation grow four types of sea-life, a sponge and some sea lilies or the like, one on the left side and three on the right. To the left two fish are swimming near the rock and close to it on the right there is an octopus. There are three labels with lines pointing to the smoke, to the vents, and to the cavity in the rock formation containing the Santa hats and fragments.]
Top label: Smoke
Middle label: Chimneys
Bottom label: Santas being digested
[Caption below the panel:]
Ocean fact: Hydrothermal vent black smokers actually evolved as predatory chimney mimics to feed on benthic Santas.

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Current text: "... but could theoretically repopulate the surface if there were ever extenctions in the real world, as there have been in prior times."
Should extenctions be extinctions? 12:01, 26 December 2023 (UTC)

I was the one who (somehow mis)typed that, and indeed it should. If it hasn't been corrected by the time I get there, I'll do it. (Related, or not, but my on-screen keyboard appears to have updated over the last day or so. I had to reset it back to how I like it (no drag-to-type, no 'suggestions' bar above, remove the emoji button) and I'm sure it's also resized vertically, meaning I may mis-hit 'keys' on different rows, but not sure how I got 'e' instead of 'i'. Put it down to an inexicable Thinko, perhaps?) Also, I might change to make clear that (e.g.) hydrothermic crustacea might (re)redevelop 'regular' phototropic versions (or those atuned to photosynthesis-rooted food webs, or something), instead of being chemosynthesis-rooted. But that could be too difficult to summarise.
...darnit, where's the tilde on this changed OSK? (Ah, there it is. Looks like they added a 'handy' numberpad setting, which I need to switch away from to get where the ~ still resides!) Yet another bothersome 'improvement' that I'll have to see if I can deal withn in the settings... Sheesh... 14:18, 26 December 2023 (UTC)

Regarding the ethology of the benthic species of Rangifer tarandus, the May-Marks navigational hypothesis has now been largely supplanted by the idea of the "angler deer", in which the low-frequency luminescence around the covering of the turbinate bones is used used as a lure, attracting abyssopelagic subspecies of Daucus carota that would ordinarily avoid regions of such extreme temperature. Yorkshire Pudding (talk) 12:23, 26 December 2023 (UTC)

This may well be the most dark Christmas comic ever in the history of xkcd! And not even really funny. Don't get my wrong I can still be amused but find it a bit out of the ordinary for saying Merry Christmas ;-) --Kynde (talk) 13:36, 26 December 2023 (UTC)

Oh, don't worry, this only traps benthic santas. As you'll have noticed, your own Julemanden has remained unaffected... As you can tell by the lack of charboiled reindeer or nisser, just beyond the 'chimneys' themselves. 14:18, 26 December 2023 (UTC)
Fun fact: Benthic santas independently evolved the familiar "Santa" body plan. They are actually more closely related to spiders. 17:40, 27 December 2023 (UTC)
Hmm. It's not clear from the comic how many legs benthic Santas have: two, eight, or six. BunsenH (talk) 19:03, 27 December 2023 (UTC)
I've just been re-reading an old Far Side collection, and thinking that this comic would be the kind of thing that Gary Larson would draw. Except that he would probably have included a pair of comical googly Santa eyes, staring at the reader. BunsenH (talk) 17:01, 28 December 2023 (UTC)

The link to an article explaining Buffy the Vampire Slayer's slayer replacement system, is humorous & mostly apropos, but I feel that a link to The Santa Clause would be much more directly relevant?

The ecology and behavior of "benthic santas" (putative taxon Abyssosanta bathytroglodyta) may have been [ahem] profoundly different from the extant species. The clues are few, but they support the hypothesis that A. bathytroglodyta sought out chimney-like structures and other crevices for shelter and food, to which they were perhaps guided by a symbiosis with Rangiferpisces rubrum, the red-antlered reindeerfish. Predation pressure from hydrothermal vent chimney mimics (Nigroventus abyssosantavorus) would have driven A. bathytroglodyta to the surface. In a possible analogy, the Atlantic clawed lobster, Homarus americanus, initially a deep-water species, was driven to the intertidal zone by predation from Gadus gadus (cod) and other large fish - only to be confronted with intolerable predation pressure from humans, to which they eventually adapted. By this model, the modern Santa (Santa donator) evolved from its precursor species under strong human selection pressure. At least S. donator was, from its precursor's traits, preadapted for a high-pressure existence, and for the cold and dark of the Arctic. 16:51, 26 December 2023 (UTC)

<applause /> 17:57, 26 December 2023 (UTC)
Well done! BunsenH (talk) 01:10, 27 December 2023 (UTC)

By my theory, if Black Smokers are responsible for drawing in Benthic Santas, and removing them from the ocean, White Smokers are where Pelagic Popes spontaneously spawn from. Whether the two phenomena are directly connected (e.g. mass-for-mass) requires further study. 21:34, 26 December 2023 (UTC)

I was curious about the size of hydrothermal vents. Would the benthic santas need to be gnome-sized? But it turns out they can be quite large, up to 60 meters high, with openings up to two meters across. "Opening" is somewhat misleading, though, as the vents aren't hollow pipes but are filled with internal structures "like a kitchen sponge." Santa wouldn't be able to slide down this chimney. Oh well. I still love this comic, and the phrase "benthic santa" cracks me up. 18:55, 29 December 2023 (UTC)

Overworld santas are unhindered by by the physical size/configuration of chimneys (or, indeed, if it's a mere central-heating/aircon vent), so I think they already have the possibility of ingress covered (if not the egress). 19:34, 29 December 2023 (UTC)
I'm guessing that you're looking at this page. Looking at the larger picture that's linked there... if the box marked "500 mm" is taken to mean that that's the scale of the whole image, the large pore is about 15 cm x 7 cm. If the width of the "500 mm" box is supposed to represent 500 mm, the pore is about 67 cm x 30 cm. A Santa who can navigate a chimney grating shouldn't be deterred by this. The image may not imply that a clear path with such dimensions exists all the way down, of course. BunsenH (talk) 00:22, 30 December 2023 (UTC)