Even though jellyfish have been thriving for millions of years, there's suprisingly little research into these elusive marine creatures. Now scientists are trying to find out more about them, and the critical role they play in ocean ecosystem.
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00:00Jellyfish are among Earth's oldest inhabitants.
00:04Mass occurrences, known as blooms of jellyfish, happen roughly every 10 years.
00:09But in some regions, like along the Namibian coast, they seem to occur more frequently.
00:14But it's hard to get data. Jellyfish drift with the current,
00:18which makes them difficult to accurately record.
00:22Such invasions are usually the result of environmental conditions,
00:26which lead to a drop in the number of predators.
00:30At the same time, that can be facilitated by an increase in temperature.
00:34You increase the temperature, these things will grow faster.
00:38You drop the concentrations of oxygen, that will affect fish negatively,
00:43but it doesn't affect jellyfish.
00:45So jellyfish will thrive in areas that fish have been forced to abandon.
00:50The invasion has not yet hit South Africa.
00:53Krish Lewis is a jellyfish expert who is familiar with the species in the waters off Cape Town.
00:59So far, 20 species are known here, such as the frilly mouth jelly and the poisonous box jellyfish.
01:05Researchers are only now beginning to understand the role that these invertebrates play in the marine ecosystem.
01:12They not only serve as an indicator species to show us when the ecosystem is out of whack,
01:17but they also play a very important role as a prey species, as well as predators in the ocean.
01:22Of course, jellyfish are predators. They actually lock up a lot of carbon into the ocean,
01:26and when those jellyfish die, they actually sink to the bottom of the seafloor.
01:29And in the following season, with wind-induced upwelling,
01:32that nutrient gets reused by the phytoplankton in order to grow and start that cycle back again.
01:37There's a lot more to learn about species diversity, too.
01:41Verena Russ has spent just over a decade studying jellyfish.
01:45Together with other scientists, she wants to build a database
01:49of the different types found off the South African coast
01:52to determine whether there are any changes in their numbers.
01:55But it's a huge task.
01:57We get small bits of tissue, we extract the tissue, we get the DNA out of the tissue,
02:02and all that's left is this little solution filled with DNA.
02:06What we then do is we sequence the DNA and we look at what species we are seeing based on the DNA.
02:12And what I can say is we are seeing many, many new things coming up from our collections.
02:16We've only maybe worked through about 10% of our collections
02:19and already we are discovering many, many new species.
02:22And so this has been very exciting for us.
02:24The more the researchers understand about jellyfish types and their numbers,
02:28the better they can determine changes in the population and correlate them with climatic conditions.
02:34Jellyfish certainly seem to feel at home here,
02:37as the coast of South Africa is one of the most species-rich in the world.
02:41Around 10% of all jellyfish species live here,
02:45and many can be seen at the Cape Town Aquarium.
02:48Each species has its own peculiarities,
02:51with some only living in cold water, others in warm.
02:54Krish Lewis is responsible for breeding them.
02:57It's a complex and difficult task.
02:59Each species has its own parameters.
03:02So while they're growing up, some species want to live in warm or cold water for certain periods of time.
03:07They diet shift.
03:08We have some jellyfish that eat other jellyfish,
03:10so we actually have to produce enough jellyfish in order to feed them.
03:14Then also, some jellyfish aren't very long-lived.
03:16They live for six months or nine months.
03:18So we always need to have this conveyor belt system
03:20where we're actually growing new species to replace the ones that are actually expiring on exhibit,
03:25as well as the flow in the tanks.
03:27The ocean is very good at keeping the jellyfish healthy,
03:30but as the jellyfish grow in the tanks,
03:32we actually have to adjust the flow so they can grow optimally,
03:35as the jellyfish become very misshapen and actually die and perish because of that.
03:41Many people are fascinated by these aquatic dinosaurs,
03:45or fear them, because many jellyfish are poisonous,
03:48although only a few species are dangerous to humans.
03:52Some jellyfish also contain hyaluronic acid and important nutrients like proteins,
04:00making them a popular food in Asia.
04:03But they're not on the menu in South Africa yet.
04:06Instead, scientists here hope to better understand the role of jellyfish within the marine ecosystem
04:12and how it's affected by climate change.