Headscratchers / Alien Worlds (2020)

• Atlas:
  • The sky grazers having to "beach" themselves on land and die to reproduce seems incredibly inefficient, especially considering how the parent's death seems to be due to being unable to take off again and nothing to do with their actual lifespan. You'd think they'd select for less-lethal means of reproduction like giving live birth to already-flighted, precocial young, laying their eggs in flight over suitable territory, or resting near steep cliffs where they can haul themselves off the cliffs to get airborne again and also give a shorter distance for their young to traverse before flying.
    • Octopus mothers take such care of their eggs that when they hatch, they starve to death, and I think I remember that there is a species of mantis that dies shortly after its young are born.
    • Creatures that die during spawning are very common — salmon are a famous example. Generally speaking, a reproductive strategy that's capable of reliably producing many offspring will be selected for, regardless of whether there are theoretically more efficient alternatives.
  • So how do the balloon predators change direction and fly back up if they've already expelled all their hydrogen stores to swoop down?
    • The former is addressed: they have tiny wing that allow them to steer. The latter, their symbiotic bacteria can probably make gas in record time.
• Janus:
  • The clip only shows the twilight-pentapods spawning and their spawn then becoming the desert-pentapods in the day half and the tundra-pentapods in the night half. Yet only the twilight type is shown spawning so how do the other types reproduce? And how have they not become different species yet?
    • They may be played in the same way and it was just not necessary to repeat the sequence.
    • It is explicitly said that certain genes are activated depend on where the eggs fall; for them to become a really different species, it would be necessary to prevent the members of the sides ^note day, night and twilight side from reproducing each other.
• Eden:
  • So the gremlin-like tree predators just willingly eat infected prey and die themselves? Wouldn't there been evolved an instinctive aversion to prey that doesn't act right?
    • There are several possibilities^note they are not mutually exclusive : like the cone snails, they use various poisons to precisely avoid this; as in many real cases, the poison is tasteless; certain individuals have resistance, but they represent a small part of the population; lastly, many real life predators use venom, but prey have not developed any immunity to it.
  • How would the rabbit-moths "worm-spawn" help in reproduction in any way? And how come the larvae develop in cocoons hanging from trees when their primary predator is arboreal?
    • In the episode it is explicitly said that more or less at that time the predators leave due to the lack of prey.

---