Reef Ramblings

Researchers from Tel Aviv University zoology department have reported previously unknown behaviour regarding feeding in a Large Polyped Stony Coral.

Whilst carrying out a survey dive of Fungiids, Mushroom Corals, on reefs off of the coast of Eilat the researchers took photographs documenting Fungia scruposa feeding on, Aurelia aurita, Moon Jellyfish. Previously, scientists believed these corals to feed on zooplankton in the range 0.2 to 0.4 millimetres in size.

Photo courtesy of TAU.

This is the first documentation of a coral feeding on a jellyfish almost equal to its size. F. scruposa can grow to around 30 cms in diameter while A.aurita ranges from 5 cms up to 40 cms in diameter. The fact that corals are capable of devouring prey several orders of magnitude larger than previously thought - was unknown to science until now.

Aquarium observation.

Although I’ve not seen this behaviour myself, I have come across something tantalisingly similar. A few years back I was maintaining a dozen or so juvenile specimens of Cassiopea species, Upside Down Jellyfish, at around 2 cms in diameter. Needing some extra room to accommodate some juvenile Fungia species of around the same size, I added the corals to the Jelly tank without a second thought. Within a couple of days I started to see jellies being injured by the corals and had to separate the two species.

Now although reef scientists may have thought that these corals only eat small zooplankton, in captivity it’s obvious that Fungiids are quite capable of coping with far larger prey items, my Fungia are regularly fed adult PE Mysis which can be up to 2 cms in length. It’s interesting to note that these corals do appear to have a sizeable mouth in comparison to other coral species, a 10 cm diameter specimen of mine has a mouth around 3 cms in length. Given this large mouth size it seems that they may be adapted to a larger prey size, although their main mode of feeding is to catch small particles on their upper surface which are then slowly transported to the mouth.

Tim Hayes

Midland Reefs

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