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Why Are Zoologists Interested in Jellyfish?

To those who have never seen them, jellyfish might seem like a peculiar curiosity -- slimy creatures that vaguely resemble the aliens from some B movie horror flick. Nevertheless, as many zoologists can testify, the better you get to know jellyfish, the more fascinating they become. And you should study them for other reasons besides mere fascination: some species have furnished molecular biologists with valuable tools, and others are dangerous to humans.

Poisonous Species
- Some species of jellyfish are poisonous to humans, so it's important to know more about these species to reduce the risk that swimmers will come in contact with them. Examples include the Portuguese Man of War and the box jellyfish. The venom the latter employs is one of nature's deadliest poisons. Curiously enough, sea turtles are able to eat box jellyfish without any ill effects. Knowing more about these poisons can help scientists to develop antidotes.
Ecology
- Jellyfish are an important part of the ocean ecosystem. According to a paper in the journal Trends in Ecology and Evolution, 124 species of fish and 34 species of other animals feed on jellyfish either occasionally or all the time. Some endangered species are among them. This predation can often be two-way; jellyfish sometimes prey on the eggs and larvae of fish that eat them. Human activities like anthropogenic climate change and overfishing can also destabilize ecosystems in ways that allow jellyfish to flourish, so scientists hope by studying them to learn more about the effects of human activity on the marine environment.
Food
- Some Asian cultures eat jellyfish. China, Japan and Malaysia are among the 15 countries with jellyfish fisheries. Worldwide, some 425,000 metric tons of jellyfish are harvested each year. Jellyfish predation on fish eggs and larvae can also impact the abundance of fish that humans harvest for food. According to the 2009 paper in Trends in Ecology and Evolution, a dramatic rise in the Black Sea population of Mnemiopsis contributed to the collapse of important Black Sea fisheries.
Molecular Biology
- Studying jellyfish has often led to important and unanticipated discoveries. The most famous example is green fluorescent protein. Today, this glowing fluorescent molecule is one of the most important tools in molecular biology research. The gene that codes for it was originally identified in a luminous species of jellyfish called Aequorea victoria. Scientists don't know yet why the ability to glow would benefit this particular species, although they do know the gene they found in this species has become invaluable to modern science.

Nature