Glowing zooplankton after eating glowing bacteria 390.
(photo credit: Courtesy of Hebrew University)
Spookily shaped glow-in-the-dark ghouls are apparently not limited to late-night
Halloween trick-or-treating, Hebrew University researchers have
A twinkling contingent of marine bacteria actually uses its
light-up capabilities to lure in its plankton predators, who consume – but are
unable to digest – the microscopic pathogens that then live off of and continue
to glow inside the planktons’ guts, according to the researchers. In turn, the
now glowing plankton, usually zooplankton, attract the eyes of predatory fish
who dine on them.
While the phenomenon of bioluminescence has long since
been identified, the researchers have for the first time identified the reason
why the marine bacteria glow – so that they might attract the predators that
give them an environment of plentiful nutrition. Such conclusions recently
appeared in the Proceedings of the National Academy of Sciences of the USA
(PNAS), based on research carried out by graduate student Margarita Zarubin at
the Inter-university Institute for Marine Sciences in Eilat under the supervision
of Hebrew University Prof. Amatzia Genin, the head of the Evolution, Systematics
and Ecology Department there.
Although it might seem counterintuitive
that zooplankton would continue to be attracted to a species of bacteria that
preys upon their digestive system, any luminescence in the water indicates to
the plankton that there is a presence of rich organic material, some of which it
might want to consume, according to Genin.
“It is worthwhile for the
zooplankton to take the risk of becoming glowing themselves when contacting and
consuming the particle with glowing bacteria, since the profit of finding rare
food there is greater than the danger of exposing themselves to the relatively
rare presence of predatory fish,” Genin said.
In their research, the
scientists discovered that nocturnal fish are able to easily detect and consume
glowing zooplankton, but that the fish are not attracted to darker forms of the
Meanwhile, the bacteria that managed to thrive in the digestive
systems of the zooplankton often are able to then prey upon the guts of the
larger fish as well.
“As far as the bacteria are concerned, their access
to the fish digestive systems is like reaching ‘paradise’ – a safe place, full
of nutrients, and also a means of transport into the wide ocean,” Genin said.