Predatory fish digestive system

glowing-bacteria-petri-dishMany creatures in the sea glow in the depths of the deepest trenches of the oceans. Bioluminescence is even observed in some marine bacteria, which emit a steady light once they have attained a certain level of concentration of organic particles in ocean waters, which is known as quorum sensing.

In a new article published in the journal Proceedings of the National Academy of Sciences (PNAS), researchers at the Hebrew University of Jerusalem discovered that light emitted by the bacteria attracts predators, generally zooplankton, which ingest the bacteria but are unable to digest them. The bacteria continue to grow inside the zooplankton, which are then attacked by their own predators, fish, which can easily spot the glowing zooplankton.


In the laboratory, nocturnal fish easily ingested glowing plankton, while they were not attracted to the zooplankton which had undergone genetic mutations to prevent the glowing.

The bacteria even survived the passage through the fish. Once they reach the digestive system, the marine bacteria have reached their goal, since it’s full of nutrients.

The phenomenon of quorum sensing that regulates the bacterial bioluminescence explains that zooplankton realize that the light in the water indicates the presence of a rich source of organic material, material on which the bacteria grow. The zooplankton take the risk of becoming glowing themselves, since food is rare and exposing themselves to the relatively rare presence of predatory fish is worthwhile.

Impact of spear fishing on the abundance of large predatory coral reef fishes
Book (The University)

Do we really want to save it?

2008-09-23 06:43:39 by oikos

The article does not mention that the sea lamprey is not a native fish and that salmon were existing quite nicely without them, seals and sea lions notwithstanding. Further the article glosses over the fact that the adult sea lamprey is parasitic/predatory (the definition breaks down with them) on the adult salmon, negating the supposed benefit of providing alternate prey for the pinnipeds. There are, however, non-parasitic lampreys that would provide the benefits without the drawbacks.

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