It's the world's largest inland sea, with a total area of almost 150,000 square miles. Countless fish call it home, thousands of seals, and all these creatures face an uncertain future now thanks to a translucent intruder just a few inches long.
The intruder is a jellyfish like creature originally from North America, the Leidy's Comb Jelly, and its arrival in the Caspian Sea between Europe and Asia is most assuredly an unwelcome one. Just look at what happened to the nearby Black Sea in the late 1980s when these same jellies appeared there: fish populations plummeted while the comb jellies reproduced unchecked.
What makes the Leidy's Comb Jelly so devastating? Quite simply, its appetite. In the Black Sea these creatures consumed not only the zooplankton that indigenous fish ate but also the eggs and larvae of the fish themselves. Compounding matters is the fact that the comb jellies, which were inadvertently brought from North America in the ballast water of ships, lack sufficient predators in their new home.
A possible solution to the crisis, then, is to introduce Leidy's Comb foes into the Caspian Sea. One species of fish from North America is said to be able to eat ten times its weight in jellies per day. Such introductions are risky, though, and can create more problems than they solve. Whatever scientists decide, they'll have to act fast. The Caspian Sea is already teeming with Leidy's Comb Jellies, and it's only been two years since the first specimen was detected there.