How Do Animals Know Which Way is Up?

TL;DR

Animals, such as jellyfish, snails, flies, and crickets, have unique gravity sensing organs that allow them to navigate and orient themselves in space. Studying these organisms can provide insights into how they adapt to environments with different levels of gravity.

Transcript

Thanks to Brilliant for supporting this SciShow List show. To keep building your STEM skills beyond this video, check out Brilliant.org/SciShow. That link will give you 20% off an annual premium subscription! [♪ INTRO] When you run to catch the bus, go for a swim and need a breath of air, or do pretty much anything else, your vestibular system is t... Read More

Key Insights

• 👾 Animals have adapted unique gravity sensing organs to navigate and orient themselves in space.
• 😒 Jellyfish use rhopalia along their bell to sense gravity and coordinate movement.
• 🥌 Snails utilize statocysts filled with stones or a single stone suspended by hairs to determine their position.
• ⚖️ Flies have chordotonal organs on their antennae and balancing rods called halteres to detect changes in pressure and maintain balance.
• 👱 Crickets have specialized structures with pendulum-like hairs on their rears to sense gravity and movement.
• 🕴️ Different animals have different sensory setups to suit their specific modes of movement.
• 🪼 In microgravity, the movement coordination of rhopalia in jellyfish becomes disrupted.

Questions & Answers

Q: How do jellyfish sense gravity in the absence of semicircular canals?

Jellyfish use fringe along their bell called rhopalia, which bends with gravity to help sense orientation. The rhopalia contain three types of cells that detect movement, transmit information to the brain, and coordinate muscle control.

Q: What are statocysts and how do snails use them to sense gravity?

Statocysts are gravity sensing organs in snails that contain stones or a single stone suspended by hairs. When the snail moves, the stones are jiggled around by moving hairs, providing information about the direction of gravity.

Q: How do flies sense gravity and maintain balance?

Flies have chordotonal organs on their antennae that sense changes in pressure due to gravity. They also have balancing rods called halteres that allow them to maintain balance and detect tiny movements.

Q: How do crickets detect gravity using pendulums?

Crickets have specialized structures on their rears covered with hairs of different lengths. These hairs act like pendulums, with longer hairs being more sensitive to slight movements. They provide information about gravity and help the crickets maintain orientation.

Summary & Key Takeaways

• Animals have different structures for sensing gravity, such as semicircular canals in jellyfish, statocysts in snails, chordotonal organs and halteres in flies, and pendulums in crickets.

• The rhopalia in jellyfish bend with gravity and help with both movement and muscle control. In microgravity, the movement of rhopalia becomes uncoordinated.

• Snails use statocysts filled with stones or a single stone suspended by long hairs to sense gravity and determine their position.

• Flies have chordotonal organs on their antennae that detect pressure changes due to gravity and are also equipped with balancing rods called halteres.

• Crickets have specialized structures on their rears covered with hairs of different thicknesses and lengths that act as pendulums to sense gravity.