Jellyfish Facts: Ancient Creatures of the Sea
Jellyfish have survived for over 500 million years - predating dinosaurs and even trees. These mysterious creatures continue to thrive in every ocean.
Basic Biology
What Jellyfish DON'T Have
- No brain (nerve net instead)
- No heart (no blood either)
- No bones (95% water)
- No eyes (some have light-sensing spots)
- No lungs (absorb oxygen through skin)
Body Structure
- Bell - the main body (umbrella shape)
- Tentacles - for catching prey
- Oral arms - transfer food to mouth
- Mouth - also serves as waste exit
The Immortal Jellyfish
Turritopsis dohrnii can theoretically live forever:
- When stressed, injured, or old
- Reverts back to polyp stage
- Grows into new adult jellyfish
- Can repeat indefinitely
- Only known "biologically immortal" animal
Jellyfish Stings
How Stinging Works
- Tentacles covered in nematocysts (stinging cells)
- Touch triggers explosive release
- Microscopic harpoons inject venom
- Happens in microseconds
Most Dangerous Species
| Species | Danger Level | Location |
|---|---|---|
| Box Jellyfish | Potentially fatal | Australia, Asia |
| Irukandji | Potentially fatal | Australia |
| Portuguese Man o' War | Severe pain | Atlantic, Pacific |
| Lion's Mane | Painful | Cold waters |
| Moon Jelly | Mild sting | Worldwide |
Jellyfish Blooms
Why Blooms Happen
- Rising ocean temperatures
- Overfishing of competitors
- Nutrient pollution
- Fewer predators
Impact
- Clog power plant intakes
- Destroy fishing nets
- Clear beaches of tourists
- Disrupt ecosystems
Incredible Abilities
1. Bioluminescence
- Many species glow in the dark
- Create their own light chemically
- Used for defense and communication
2. Regeneration
- Can regrow lost tentacles
- Some regenerate entire body
- Turritopsis can completely restart
3. Survival
- Exist in every ocean zone
- Handle extreme temperatures
- Thriving despite climate change