Jellyfish 101 | Nat Geo Wild

Summary

Jellyfish, invertebrates with a mesmerizing presence in oceans worldwide, have existed for hundreds of millions of years. Despite their name, they are not fish but belong to two distinct biological phyla, with thousands of species. Composed mainly of water and a gelatinous substance called mesoglia, they lack bones, brains, and blood. The Turritopsis dohrnii, known as the 'immortal jellyfish,' can reverse its aging process through transdifferentiation. Not all jellyfish sting, but the box jellyfish is the most venomous, with tentacles capable of causing paralysis or death. Jellyfish blooms, dense groups that form for mating, can span hundreds of square miles and have caused significant disruptions globally. Scientists estimate that there may be as many as 300,000 undiscovered species, highlighting the enigmatic nature of these sea creatures.

Takeaways

• 🌍 Jellyfish inhabit a wide range of marine environments, from deep oceans to shallow coastal waters.
• 🕵️‍♂️ Despite their name, jellyfish are not fish but belong to two different biological phyla, making 'sea jellies' a more accurate term.
• 🧬 As invertebrates, jellyfish lack backbones, brains, and blood, yet they exhibit remarkable diversity with thousands of species.
• 🔬 The 'immortal jellyfish' (Turritopsis dohrnii) can reverse its aging process through transdifferentiation, restarting its life cycle.
• 🐠 The box jellyfish, particularly the Australian box jellyfish (Chironex fleckeri), is the most venomous marine animal, capable of causing rapid paralysis and death.
• 🏥 Approximately 150 million jellyfish stings are reported annually, affecting both humans and other marine animals.
• 💧 Comprising 95% water, jellyfish have a simple structure without hearts, blood, or bones, and possess basic sensory organs.
• 🌊 Jellyfish 'blooms' or 'swarms' can form rapidly, sometimes becoming so dense that they cause ecological and economic disruptions.
• 🌐 Jellyfish blooms have been known to clog fishing equipment, damage ships, and close beaches, impacting various regions globally.
• 🔬 Scientists estimate that there may be as many as 300,000 species of jellyfish yet to be discovered, indicating the depth of our mystery surrounding these creatures.

Q & A

Where can jellyfish be found?

Jellyfish can be found all over the world, from deep oceans to shallow coastal areas.

How long have jellyfish existed?

Jellyfish have been around for hundreds of millions of years.

What makes jellyfish unique in comparison to fish?

Jellyfish are unique because they are boneless, brainless, and bloodless, and they belong to two different biological phyla, making them invertebrates unlike fish which have backbones.

What is the scientific term used to describe the jelly-like material that jellyfish are made of?

The jelly-like material that jellyfish are made of is called mesoglia.

Why do scientists sometimes use the term 'sea jellies' instead of 'jellyfish'?

Scientists have started using the term 'sea jellies' to clear up confusion as 'jellyfish' is a broad term that encompasses thousands of different species.

What is special about the Turritopsis dohrnii jellyfish?

The Turritopsis dohrnii, also known as the 'immortal jellyfish,' is unique because it can reverse the aging process through a process called transdifferentiation, allowing it to revert back to a polyp and begin its life cycle anew.

Which jellyfish is considered the most venomous?

The Australian box jellyfish, or Chironex fleckeri, is considered the most venomous marine animal in the world.

What are the potential effects of a box jellyfish sting on humans?

A sting from a box jellyfish can cause paralysis, cardiac arrest, and even death within just a few minutes.

What percentage of a jellyfish is water?

Jellyfish are 95% water.

What happens to a jellyfish if it washes up on the beach?

If a jellyfish washes up on the beach, it will mostly evaporate due to its high water content.

What are the different terms for a group of jellyfish?

Groups of jellyfish are called blooms, swarms, or smacks.

Why do jellyfish blooms form and what problems can they cause?

Jellyfish blooms form quickly, often for mating purposes. They can cause problems such as clogging fishing equipment, destroying ships, and closing beaches in various parts of the world.

How many species of jellyfish are there, and how many might we not have discovered yet?

There are thousands of known species of jellyfish, but scientists believe there may be as many as 300,000 species that we haven't yet discovered.