Podcast Summary: Who Smarted? – "Do Fish have Eyelids?"

Date: March 23, 2026
Podcast by: Atomic Entertainment / Starglow Media
Theme: Do Fish Have Eyelids? The Sleepy Secrets of Underwater Creatures

Episode Overview

This lively episode dives underwater to explore an unusual question: Do fish have eyelids? Along the way, the Who Smarted? crew uncovers how various sea creatures handle sleep, busting myths and sharing weird, wonderful adaptations—from jellyfish "sleeping" without a brain to dolphins half-awake with one eye open. The episode masterfully blends fun banter with sharp facts, making science about the ocean's sleepers both hilarious and memorable for curious young listeners and their families.

Key Discussion Points & Insights

1. Setting the Scene: How Do Underwater Animals Sleep?

• Narrator introduces the topic by relating human and pet sleep needs to the mysterious world of marine animals.

  “But what about sharks, whales, dolphins, or even just your pet goldfish? How do creatures who live in water sleep? Or do they?” (01:16)

• Transition from human habits to the enigmatic sleep routines under the sea.

2. Do Fish Have Eyelids? (And Are They Sleeping?)

• Fish do not have eyelids, so when seen resting with open eyes, they’re often still sleeping.

  “Just like fish, they don’t have eyelids. So when they sleep during the day, their eyes appear to be wide open.” (04:07)

• Moray eels and other nocturnal species may look awake but are often resting.
  Memorable Moment:

  ERNIE: “You awake him.”
  IRENE: “I’m telling you, they’re not asleep.”
  (03:00)

3. Unique Sleeping Styles of Fish

• Fish sleep in short rest periods rather than one long stretch.
• Sleep adaptations:
  • “Some fish float in place, others wedge themselves into mud or coral, and some even find a suitable nest.” (04:26)
• Sharks: Contrary to the myth, some can rest while hardly moving; nurse sharks can be completely still while sleeping.

  “Whatever method a particular shark uses to breathe, they’re able to do it during periods of deep rest while remaining fairly still.” (05:02)

  • Parrotfish uniquely protect themselves by encasing in a mucus sleeping bag at bedtime.

    “This sleeping bag protects it from predators.” (05:24)

4. Sea Mammals: Sleeping with One Eye Open

• Dolphins and whales demonstrate unihemispheric slow-wave sleep: half their brain sleeps at a time, with one eye open.

  “When a whale or dolphin goes to sleep, only half their brain shuts down and only one eye closes.” (06:15)

• This adaptation helps them remain partially alert for predators and enables them to surface for air.

  “It’s the opposite eye from whichever half of their brain shuts down… This allows them to literally keep an eye out for predators.” (06:25)

• They alternate brain sides every two hours and clock ~8 hours of sleep daily.

  “This method is known as unihemispheric sleep.” (07:33)

5. Behind the Scenes: A Marine Biologist Explains

• Becky, the marine biologist, provides hands-on insights from her research.
  • Describes quiet observation settings and hints at unique sea creatures (jellyfish!) who sleep in strange ways.

    “What sea creature can glow in the dark, use its tentacles to sting its prey... and can be found in both freezing Arctic oceans and tropical seas?” (09:14)

  • Jellyfish: No central brain or nervous system; survived since before dinosaurs.

    “No, I’m saying the jellyfish is a ‘no brainer’ because it has no brain.” (10:10)

    • Even without a central nervous system, jellyfish exhibit rest cycles. If disrupted, they’re “slower to respond to things the next day.” (13:00)

6. More Marvelous Marine Sleep Tricks

• Walruses: Inflate air sacs in their necks to float and keep their faces out of water while sleeping.

  “Walruses have an air sac on their neck that inflates... allowing them to float.” (13:32)

• Seahorses: Curl their tails around plants or coral to anchor themselves mid-slumber.
• Baby sea otters: Hold hands with their moms so they don’t drift apart while sleeping.
• Sea stars: Use arm suckers to cling to rocks as they sleep.
• Octopuses: Experience both ‘quiet’ and ‘active’ sleep phases, including changing color and eye movements.

  “During active sleep, they may change color and their eyes flicker around.” (14:11)

7. Goldfish: Sleepy Pet Facts

• Goldfish rest by hovering in place, usually head down, in dark and quiet environments at home.

  “Like all fish, goldfish do not lie down when they sleep. Rather, they become less active… Goldfish sleep about eight to twelve hours every day, usually when it’s dark and quiet.” (14:24)

Notable Quotes & Memorable Moments with Timestamps

• “Just like fish, they don’t have eyelids. So when they sleep during the day... their eyes appear to be wide open.” — Narrator (04:07)
• “I’m telling you, they’re not asleep.” — Irene (03:02)
• “Whatever method a particular shark uses to breathe, they’re able to do it during periods of deep rest while remaining fairly still.” — Narrator (05:02)
• “This sleeping bag protects [parrotfish] from predators.” — Narrator (05:24)
• “When a whale or dolphin goes to sleep, only half their brain shuts down and only one eye closes.” — Narrator (06:15)
• “The jellyfish is a no brainer because it has no brain.” — Becky (10:10)
• “Even though jellyfish lack some of the essential organs and systems... they too need to catch some Z’s.” — Becky (13:14)
• “Walruses have an air sac on their neck that inflates when they sleep to keep their face out of the water and allowing them to float.” — Becky (13:32)
• “Baby sea otters hold hands with their mommies to keep from floating away when they sleep.” — Becky (13:45)

Important Segments & Timestamps

| Timestamp | Segment Description | |-----------|-----------------------------| | 00:02 | How do animals (including fish and sea creatures) sleep? | | 02:20 | Introduction of moray eel and nocturnal animal sleep | | 04:07 | Fish have no eyelids—yet they sleep! | | 05:17 | Parrotfish “sleeping bag” adaptation | | 06:15 | Dolphins and whales' unihemispheric sleep explained | | 09:14 | Marine biologist Becky introduces jellyfish and brainless sleep | | 13:00 | Jellyfish rest, sluggishness when sleep deprived | | 13:32 | More fascinating aquatic sleep tactics (walrus, seahorse, otter, starfish, octopus) | | 14:24 | Goldfish sleep facts for pet owners |

Episode Takeaways

• Fish and many sea creatures DO sleep, but their methods are often wildly different (and cooler) than ours—ranging from “eyes wide open” resting to half-brain alertness and even sleeping in floating “mucus sleeping bags.”
• Notably, no, fish do not have eyelids!
• Sea mammals, jellyfish, sharks, and even cute otters all showcase remarkable adaptability.
• Kids (and adults) will likely run to their fish tank or local aquarium to look for "sleeping" fish in action after hearing these fun facts!

Overall Tone

The episode is playful, curious, and slightly goofy, with every fun fact delivered in a way that’s both scientifically accurate and laugh-worthy—making marine biology totally splashy for kids and parents alike.