How Upside-Down Jellies Sting You Without Touching You

TL;DR

The upside-down jelly, also known as Cassiopea xamachana, uses stinging snot rockets to catch prey and defend itself.

Transcript

[♩INTRO] I don’t think you’re ready for this jelly. Sure, it looks kind of unassuming, what with it’s strange habit of hanging out, wrong-way up on the seafloor. But it can sting you without actually touching you. That’s all thanks to the stinging snot rockets it launches into the water above. Yes, I said stinging snot rockets. I told you you weren... Read More

Key Insights

• 🙃 The upside-down jelly, Cassiopea xamachana, anchors itself using its bell and relies on symbiotic algae for nutrition.
• 👻 It possesses stinging cells called nematocysts that allow it to catch prey.
• 🧡 Cassiosomes, swimming structures found in the jelly's mucus, act as long-range weapons to kill prey.
• 💦 The presence of cassiosomes in the mucus explains the phenomenon of stinging water reported by swimmers.
• 🪼 Other species of jellies related to the upside-down jelly also possess cassiosomes.
• ❓ Cassiosomes are believed to have evolved in the Rhizostomeae lineage to provide extra firepower.
• 🪼 Upside-down jellies are part of the most diverse order of true jellies.

Questions & Answers

Q: How does the upside-down jelly anchor itself to the seafloor?

The jelly uses its bell as a suction cup to attach itself to the bottom, similar to a sea anemone.

Q: What role do the symbiotic algae play in the upside-down jelly's life?

The algae, called zooxanthellae, provide food for the jelly through photosynthesis and receive a safe habitat in return.

Q: How do the stingers of the upside-down jelly help it catch prey?

The jelly can send stinging cells called nematocysts towards its prey, such as brine shrimp, immobilizing them for consumption.

Q: What are cassiosomes, and how are they used by the upside-down jelly?

Cassiosomes are tiny structures found in the jelly's mucus that contain stinging cells and are used as a long-range weapon to kill prey. They are released into the water to create a cloud of stinging snot rockets.

Summary & Key Takeaways

• The upside-down jelly anchors itself to the seafloor using its bell and relies on symbiotic algae for food.

• It possesses potent stinging cells called nematocysts that it uses to catch small critters like brine shrimp.

• Scientists discovered the presence of tiny structures called cassiosomes in the jelly's mucus, which act as long-range weapons to kill prey.