(PhysOrg.com) -- Corals depends on the products of photosynthetic algae for most of their food, but they also eat tiny plankton. Now, for the first time, there is evidence of a coral eating jellyfish.
Photographs of several specimens of mushroom coral (Fungia scruposa) consuming moon jellyfish (Aurelia aurita) were taken by scientists G. Dishon from Bar-Ilan University, and A. Alamaru, Y. Loya and O. Bronstein from Tel Aviv University, who were diving in the Red Sea coral reefs near Eilat in Israel. The team found the coral at depths of 2-20 meters, and the specimens observed to feed on the jellyfish were around 20-25 cm in diameter, while the jellyfish measured about 12 centimeters.
The jellyfish were present in large numbers due to a seasonal bloom caused by vertical nutrient upwelling during winter. Jellyfish blooms in the area are increasing in size and frequency.
Fish, turtles and sea birds are known to eat moon jellyfish, but this is the first time corals have been documented actively eating an adult jellyfish, according to team member Ada Alamaru. She described the discovery as "unique" and "amazing".
Corals feed on plankton, which may in turn have fed on even tinier jellyfish embryos, but no evidence of this has been found. Ms Alamaru said she did not know of any previous reports of coral feeding on jellyfish. Adding jellyfish to the diet opportunistically would give the coral valuable additional protein.
Reef-building corals consist of colonies of hundreds of polyps, but the mushroom coral consists of a single, solitary, large polyp that can grow up to 30 cm in diameter. It is not attached to the sea floor, but has very limited movement, and it is unclear how it manages to catch the jellyfish. The photographs show the jellyfish being sucked into the coral's large mouth.
The findings were published in Coral Reefs, the journal of the International Society for Reef Studies.
More information: Opportunistic feeding by the fungiid coral Fungia scruposa on the moon jellyfish Aurelia aurita, Coral Reefs, Volume 28, Number 4 / December, 2009, DOI: 10.1007/s00338-009-0507-7
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