Jellyfish get a bad rap. Few people give a second thought to these mysterious animals, beyond perhaps noting how truly alien they appear and seeing the occasional piece of news about how they are taking over the ocean. We're here to tell you that jellies are far more awesome, versatile, complex and important for our ecosystem than you may have thought.

Jellies carry some of the most unique evolutionary gifts in the animal kingdom, gifts that help them thrive in oceans that have been severely impacted by human activity. With human-jelly interaction becoming more common, we invited some of the world's leading jellyfish experts to chat to us about these interactions - these are the 10 things we learned at Jelly Night:


1. Jelly stings are the quickest things on Earth

The stinging cells on jellyfish called nematocysts, fire tiny venom-filled barbs called cnidae - the firing of these stinging cells is the quickest biological event in nature.

These cnidae accelerate at 5.4 million times the force of gravity when fired! To put that in perspective, that's 4.4 million times quicker than the new Tesla Roadster and 500 000 times quicker than the blink of an eye. The pressure that a box jelly sting can exert on impact with its prey is 7.7 gigapascals - that's about 350 times the pressure of an armour-piercing rifle bullet striking a hard target. Of course, these cnidae are very small, so there is not enough force for us to feel that pressure, but it is enough to pierce the skin of most animals.

2. Jelly mucus could save the ocean from microplastic

An international collaboration called GoJelly has discovered that the mucus excreted by the common moon jelly and nomad jellies are able to absorb tiny particles of microplastic. When the mucus sinks, it carries the plastic with it. GoJelly is working on a system of filters that can harness this phenomenon to, hopefully, begin reversing some of the plastic pollution problem affecting our ocean.

Jellyfish and plastic pollution have a lot in common. Take a look at what our "Jelly Guy" has to say on the issue.

3. Jellies and machinery don't mix

There seem to be two things that hate jellies: Swimmers and nuclear reactors. Intake pumps for cooling systems at nuclear power stations are very good at keeping small numbers of jellies out, but seem unable to cope with the hundreds or thousands of tons of jellies that get sucked in during large jellyfish blooms. This problem has caused the periodic shutdown of nuclear power stations across the globe in recent years - California, Japan, Sweden, Israel, Scotland and even South Africa's Koeberg have been affected. This problem affects other ocean-going equipment too, from ships to fishing nets, and the trend is increasing!

The USS Ronald Reagan, one of the most expensive warships ever made, was temporarily disabled by a bloom of jellyfish in Australian waters. Credit: U.S. Navy [CC BY 2.0]

4. The old treatment for stings is still the best treatment

There are many old wives' tales about the correct treatment for a jellyfish sting. But, research has shown that the best treatment for a jellyfish sting, including deadly box jellies, is to leave the sting in place, wash the sting and the entire wounded area in vinegar and then soak the wound in warm 45° water for about half an hour. Tentacles can be pulled off with gloves or tweezers. Although low-tech, this treatment is nearly as effective as some of the more difficult to acquire topical ointments.

Vinegar - the original and best treatment for jelly stings. Credit: Michael Coghlan  [CC BY-SA 2.0]

Incorrect treatment of the wound can actually cause unfired stinging cells on tentacles to fire, making the injury much worse. Pouring seawater, freshwater or petrol on the wound, or scraping off the tentacles are all guaranteed to make the wound worse! Peeing on the sting will probably not help either, unless you really dislike the victim.

5. People eat a lot of jellyfish

It is estimated that about a million tons of jellyfish are caught annually for food. Compare that to the fisheries of other invertebrates - 280 000 tons of lobster, 150 000 tons of krill and 370 000 tons of octopus. In fact, jellyfish fall right behind squid and shrimp as the most caught pelagic invertebrates!

Subsistence jellyfish fishermen near Phuket, Thailand. Credit: [CC BY 2.0]

6. Jellies kill 100 times more people than sharks

About 100 to 500 people are killed by jellyfish stings a year. Although this number is almost a hundred times higher than shark-related deaths, the people most affected by this are children under the age of 12 in the Indo-Pacific, particularly the Philippines. Many of these deaths are the result of inadequate medical facilities, poor warning systems about the presence of jellyfish and "old wives' tales" of jellyfish sting cures that actually make things worse.

Most fatal jellyfish stings are attributed to the various species of box jellyfish. Credit: Danny Cicchetti [CC BY-SA 4.0]

7. Jellyfish are ancient

Jellyfish are ancient! They appear about 600 million years ago in the fossil record - right next to comb jellies and sponges, the first complex animals on the planet.

Jellyfish aren't the only living fossils at the Two Oceans Aquarium.

A 160 million-year-old jellyfish fossil from Germany. Credit: James St. John [CC BY 2.0]

8. A Nobel Prize was awarded for jelly research

The 2008 Nobel Prize for Chemistry was jointly awarded to three scientists, Osamu Shimomura, Martin Chalfie and Roger Tsein, for the discovery and development of "green fluorescent protein (GFP)" in the North American crystal jelly. The applications of this discovery are quite complex, but basically this protein is something that can quite easily be added to organisms through genetic modification without ill effect. The use of UV light on these organisms then causes the protein to glow and this can be used, for example, to determine how a polluted environment affects fish, study cancerous tumors or allow scientists to examine otherwise invisible microorganisms under the microscope.

Under UV light the two transgenic lab mice glow green from the GFP protein, whereas the wild-type mouse in the middle does not glow. In this case, the glowing tissues allowed scientists to study and test treatments for various cancers. Credit: Ingrid Moen et al. [CC BY 2.0]

We love fluorescent animals, but prefer those that glow naturally - especially sharks!

9. There are four reasons that jellyfish numbers are increasing

The data seems to suggest that jellyfish populations are increasing globally, although further study is needed to get an exact idea of what this increase looks like. One thing is certain though - jellyfish thrive in environments that are affected by humans, here's why:

  • Eutrophication - Nutrient-rich pollutants, particularly from chemical fertilisers and sewerage rapidly increase the abundance of microscopic organisms in the areas of the ocean where they occur. This causes a huge drop in the amount of oxygen in the water, killing or deterring larger animals, like fish, from entering these polluted "dead zones." Although jellyfish prefer oxygenated water, their slow metabolisms are better able to cope with low oxygen levels than other species, and they can take advantage of eutrophication to move into new areas. 
  • Translocation - International shipping has allowed jellyfish to enter new environments, carried either as polyps stuck to the bottom of ships or in bilge water. Although most alien animals are unable to cope in their new environment, those that do survive are often able to thrive as invasive species in waters without any natural predators.
  • Global warming - Jellyfish typically spend a long time in their sessile polyp stage, waiting for the perfect conditions to mature to adult medusae so that they can reproduce. Thanks to global warming, these ideal conditions are occurring far more often for some species of jelly.
  • Overfishing - Jellies and fish share many of the same foods, and many fish actually feed on jellies. Overfishing of fish species removes competition, allowing the jellies to take over these fish-depleted waters quickly.

10. Jelly science has a lot of career opportunities!

One thing that was abundantly clear at Jelly Night was that jellies have historically been very poorly studied - but that is changing! Marine biologists, geneticists, food scientists, fisheries experts, conservationists and more are growing increasingly interested in jellyfish, like UWC's SA Jelly Lab.

These mysterious creatures still have a lot of secrets to be discovered! Learn more about South Africa's jellies at the Aquarium's Jelly Gallery.


Images courtesy of UWC SA Jelly Lab.

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