Uploaded June 2025 | Updated September 2026, 2 weeks ago
Space is big—but could life out there be even bigger? Join us as we ask just how enormous alien life can get—and what it might look like.
Watch my exclusive video Fishbowl Starships - Water As Shielding - nebula.tv/videos/isaacarthur-fishbowl-starships-water-as-shielding
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Use the link gift.nebula.tv/isaacarthur to give a year of Nebula to a friend for just $36.
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Credits:
Cosmic Megafauna - Could Giant Alien Life Forms Exist?
Episode 727; June 26, 2025
Written, Produced & Narrated by: Isaac Arthur
Select imagery/video supplied by Getty Images
Music Courtesy of Epidemic Sound epidemicsound.com/creator
Stellardrone, "Red Giant", "Billions and Billions"
Chapters
0:00 Intro
3:35 The Limits of Size in Biology
7:40 Cosmic Megafauna in Different Environments
8:28 Spaceborne Megafauna: Giant Creatures in the Void
10:18 Could Space Creatures Form Complex Ecosystems?
12:29 Giant Oceanic Creatures: Titans Beneath the Ice
18:23 Fishbowl Starships
19:45 Giants Amid the Clouds: Life Inside Gas Giants
24:53 Terrestrial Kaiju & Sandworms: Monsters on Land
31:01 Megaflora: When the Giants Are Green
34:26 True Cosmic Megafauna: When Worlds and Stars Are Alive
38:14 Final Reflections: Life Without Limits
Space is big—but could life out there be even bigger? Join us as we ask just how enormous alien life can get—and what it might look like.
Watch my exclusive video Fishbowl Starships - Water As Shielding - nebula.tv/videos/isaacarthur-fishbowl-starships-water-as-shielding
Get Nebula using my link for 40% off an annual subscription: go.nebula.tv/isaacarthur
Get a Lifetime Membership to Nebula for only $300: go.nebula.tv/lifetime?ref=isaacarthur
Use the link gift.nebula.tv/isaacarthur to give a year of Nebula to a friend for just $36.
Visit our Website: isaacarthur.net
Join Nebula: go.nebula.tv/isaacarthur
Support us on Patreon: patreon.com/IsaacArthur
Support us on Subscribestar: subscribestar.com/isaac-arthur
Facebook Group: facebook.com/groups/1583992725237264
Reddit: reddit.com/r/IsaacArthur
Twitter: twitter.com/Isaac_A_Arthur on Twitter and RT our future content.
SFIA Discord Server: discord.gg/53GAShE
Credits:
Cosmic Megafauna - Could Giant Alien Life Forms Exist?
Episode 727; June 26, 2025
Written, Produced & Narrated by: Isaac Arthur
Select imagery/video supplied by Getty Images
Music Courtesy of Epidemic Sound epidemicsound.com/creator
Stellardrone, "Red Giant", "Billions and Billions"
Chapters
0:00 Intro
3:35 The Limits of Size in Biology
7:40 Cosmic Megafauna in Different Environments
8:28 Spaceborne Megafauna: Giant Creatures in the Void
10:18 Could Space Creatures Form Complex Ecosystems?
12:29 Giant Oceanic Creatures: Titans Beneath the Ice
18:23 Fishbowl Starships
19:45 Giants Amid the Clouds: Life Inside Gas Giants
24:53 Terrestrial Kaiju & Sandworms: Monsters on Land
31:01 Megaflora: When the Giants Are Green
34:26 True Cosmic Megafauna: When Worlds and Stars Are Alive
38:14 Final Reflections: Life Without Limits
