Marine biologists have discovered a lake in India filled with jellyfish, the nation's first so-called jellyfish lake. Researchers estimated the lake's bed was covered by a swath of jellyfish stretching 13 acres.

Biologists with the Wildlife Trust of India happened upon the lake during a routine field visit to Armabada, a small town in Gujarat, a state along India's northwest coast.

"There might be other lakes like this in India, but nobody has yet made them known to the world," said B.C. Choudhury, a senior advisor at the Wildlife Trust. "The concentration and density of jellyfish is very high here. You can even see them from outside during low tide and when the water is clear."

The creatures particular to the lake are a rare species called "upside-down jellyfish," (Cassiopea sp), called so they spend their lives upside down on sea beds and mud flats. Researchers say the jellyfish are also unusual in that they are present year round -- not seasonal, as is the case in most other jellyfish lakes.

"They position themselves on their bottom side to receive maximum sunlight as they harbor photosynthetic algae called Zooxanthellae, which have a symbiotic relationship with jellyfish similar to corals," said WTI marine biologist S. Goutham.