Fish
Fish
[Cueball and Megan are walking down a hill.] Cueball: The Fermi paradox keeps getting worse. If planets are common, where is everybody?
Megan: Imagine you're a scuba diver looking at the ocean floor. You know there's a fish there, but you can't see it. Why?
Cueball: Maybe the fish looks like sand. Megan: Yeah...
[Zoom out to the Earth from space.] Megan: ...and what would that tell you about the ecosystem?
[Earth moves slightly out of the panel.]
[Earth moves halfway out of the panel.]
[Blank panel.]
[A shark swims through space.]

The Fermi paradox is the contradiction that arises between high estimates of the likelihood of extraterrestial life and the fact that no evidence for it has thus far been found.
Cueball and Megan are having a conversation regarding this — since new planets are found all the time around distant stars, Cueball comments that this makes it an even greater paradox. Megan suggests that perhaps our search for extraterrestrial life is like looking at a patch of ocean floor looking for a fish. The diver knows that there must be a fish somewhere, but is unable to actually find it. She then goes on to ask why the fish would be hidden — i.e. camouflaged, and what it means about the remaining fish. The suggestion is that the fish would be hidden to avoid being eaten by predators, and perhaps the reason no extraterrestrial life is sending any sign of existence back is that they fear they might be destroyed soon after they revealed their location. Maybe they have even actively tried to hide the presence of their entire planet if they obtain the technological means. This potentially refers to the Deadly Probes scenario where a space faring species has developed deadly probes that self replicate and spread through the void between the stars - homing in on radio signals and destroying young civilizations in the cradle...
The camouflaged fish could be identified by using more sophisticated technologies like infrared cameras. Looking at the Earth from space beyond Low Earth orbit only with the naked eye wouldn't show any hint to our ecosystem . This is like the actual possibility in astronomy when observing exoplanets — the nature of those more than 1,500 known planets is unknown due to the lack of better technologies to the scientists. And there are a couple of hundred billion planets at our galaxy still camouflaged to human scientists.
The final panels take the metaphor further, suggesting that there is literally a planet sized shark swimming through space eating planets, and since the view is panning away from earth and over to the shark, the shark seems to be heading our way. It looks like Earth is the next fish, presumably because we did not reach a high enough technology level in time to recognize the danger and hide.
This also explains the title text that has the theme from the movie Jaws playing while astronomers look into their telescopes. This may also be a reference to the film Alien , which was pitched with the three word proposal " Jaws in Space."
Stephen Hawking famously warns, "If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans." Chinese sci-fi author Liu Cixin wrote an award-winning sci-fi trilogy called the Remembrance of Earth’s Past trilogy, which draws on a similar idea; the title of the second book, The Dark Forest , is a reference to the same Fermi paradox solution described in the comic. Even Carl Sagan called the practice of Broadcasting and Signaling presence of Life on Earth "deeply unwise and immature," and recommended that "the newest children in a strange and uncertain cosmos should listen quietly for a long time, patiently learning about the universe and comparing notes, before shouting into an unknown jungle that we do not understand."
[Cueball and Megan are walking down a hill.] Cueball: The Fermi paradox keeps getting worse. If planets are common, where is everybody?
Megan: Imagine you're a scuba diver looking at the ocean floor. You know there's a fish there, but you can't see it. Why?
Cueball: Maybe the fish looks like sand. Megan: Yeah...
[Zoom out to the Earth from space.] Megan: ...and what would that tell you about the ecosystem?
[Earth moves slightly out of the panel.]
[Earth moves halfway out of the panel.]
[Blank panel.]
[A shark swims through space.]
