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Jellyfish are a real headache for swimmers, sunbathers and boats. But Tel Aviv University University researchers have discovered that these translucent creatures have an enemy - sea coral. Until now, scientists thought that corals eat only tiny plankton 0.2 to 0.4 millimeters in size, and nutrients from photosynthetic algae known as Zooxanthellae. But now, doctoral student Omri Bronstein and Prof. Yossi Loya of TAU zoology department have discovered that coral also feed on certain types of jellyfish.
New photos reveal a stationary mushroom coral sucking in a large moon jellyfish. This surprising new coral feeding behavior - from photos revealing that corals are capable of devouring prey several orders of magnitude larger than previously thought - was unknown to science until now. The pictures were taken on a survey dive of mushroom corals (Fungiids) while the researchers investigated the species on reefs off the coast of Eilat and worked at the southern city's Interuniversity Institute for Marine Sciences.
Ocean currents and nutrients from the deep have created a seasonal bloom of the jellyfish (Aurelia aurita), commonly known as moon jellyfish. Every winter in the Gulf of Eilat, surface water cools down and becomes heavier, sinking to the bottom and forcing deeper water to the surface in a process called vertical mixing. Many marine organisms, including jellyfish, take advantage of this annual nutrient flux and dramatically increase in numbers.
The moon jellyfish is eaten by a number of predators including fish, turtles and sea birds. However, discovering that it is preyed upon by the mushroom coral (Fungia scruposa) is the first documentation of a coral feeding on a jellyfish almost equal to its size.
Zooxanthellae are single-celled plants that live in the tissues of animals and are known for their mutual relationship with reef-building corals, which provide them with a protected environment and compounds needed for photosynthesis. In turn, the algae provide food as products of photosynthesis to coral. This gives corals a boost of nutrients, so they can secrete the calcium carbonate skeleton that serves as the foundation for coral reef. This important mutual relationship represents a highly efficient exchange of nutrients in a nutrient-poor environment.
Unlike most reef building corals, which are colonial and are made up of hundreds of polyps, F. scruposa is solitary and composed of one large polyp, measuring up to 30 centimeters in diameter. They are not attached to the seabed and so have an unlimited ability to move, unlike their reef-building relatives.
The coral's ability to feed when a jellyfish bloom occurs provides valuable protein to the animal. This recent discovery suggests further benefits to the large-mouthed corals in a changing environment where - due to global warming - jelly blooms are increasing in frequency and intensity. The ability to use a variety of food sources and take advantage of such a bloom gives the mushroom corals an advantage compared with other small polyped corals that are not able to feed on such large prey.
JAPANESE, ISRAELI RESEARCHERS TO COOPERATE
Senior Israeli scientists will for the first time conduct joint research with Japanese counterparts on stem cells and the brain. The Science and Technology Ministry says the research will begin soon and continue for three years, coordinated by the ministry and JST - the Japanese Agency for Sciences and Technology.
Israelis from the Weizmann Institute in Rehovot, the Technion in Haifa and Tel Aviv University will cooperate with the Japanese on four new projects. The $1.2 million cost will be shared equally between the governments. Scientists from both countries have already made proposals for research after the governments asked for applications a year ago.
Science and Technology Minister Prof. Daniel Herschkowitz commented that Israel is one of the world's leaders in stem cell research. "Israel," he added, "is one of only nine countries with which Japan has signed agreements for joint research, so this is a real achievement."
Ministry chief scientist Prof. Menahem Mendelevich said the agreement is a "breakthrough in the institutionalization of joint research with Japan. We are now launching the first cycle of studies, and are sure their large scope and the choice of two important fields insure the ability of Israel to lead in stem cells."
Meanwhile, Menachem Greenblum - an accountant who was until recently director-general of GES (Tambour Ecology) - has been named director-general of the Science and Technology Ministry by Hershkowitz. The nomination was approved by the cabinet on Sunday. The minister said Greenblum, 59, would add much with his knowledge of renewable energy such as desalination. He has served as a director of a number of public companies.