March 2021, ScientificAmerican.com 19FROM “ALGAL PLANKTON TURN TO HUNTING TO SURVIVE AND RECOVER FROM END-CRETACEOUS
IMPACT DARKNESS,”BY SAMANTHA J. GIBBS ET AL., INSCIENCE ADVANCES,VOL. 6, NO. 44;OCTOBER 30, 2020PALEOBIOLOGYPredatory
Algae
When the sun disappeared,
tiny coccoliths became huntersAn asteroid strike 66 million years ago not
only devastated the dinosaurs but almost
reset life in the oceans back to a primitive
soup of simple microorganisms. What pre-
vented ocean ecosystems from totally col-
lapsing, scientists hypothesize, may have
been shell-covered algae that could feed on
other organisms but maintained the ability
to photosynthesize. This skill would preserve
the foundation of the marine realm’s com-
plex food webs through a long dark spell.
The predatory plankton belonged to
a family of armored, algaelike organisms
called coccolithophores, or coccoliths. They
have been around for about 200 million
years, and many forms still bob along as
ocean plankton today. But their survival was
especially significant in the wake of the mass
extinction at the end of the Cretaceous peri-
od, when debris from the asteroid’s impact
and wildfire ash blotted out the sun for two
years. Life experienced a prolonged “impact
winter” when photosynthesis all but ceased.
“The food webs in the ocean have pho-
tosynthesis as their foundation, just like the
land, but in the ocean the photosynthesis
is carried out by microscopic bacteria and
algae,” says University of Southampton
paleontologist Samantha Gibbs, lead authorof a new study in Science Advances. Cocco-
liths were among these energy converters
in the Cretaceous, and about 90 percent of
coccolith species went extinct after impact.
Lacking light for their energy needs,
Gibbs says, “the handful of survivor species
were able to turn to food capture and inges-
tion.” Small holes in coccolith fossils indicate
that the survivors possessed whiplike flagel-
la that let them move and stalk other organ-
isms. The researchers tracked hunter
algae’s prevalence in the fossil record and
modeled the organisms’ evolution to show
how they could have survived and adapted
to the sun’s disappearance—and then its
return, when they proliferated again.
Experts have long wondered how pho-
tosynthesis-using organisms such as coc-
coliths endured without sunlight. “This is a
really exciting finding that goes a long way
to explaining an apparent paradox in the
extinction,” says University of Texas at
Austin paleontologist Christopher Lowery,
who was not involved in the study.
The model may explain changes in other
organisms as well. Small creatures called
foraminifera, or forams, also took a hit from
the impact but persisted. They were
armored, too, and those that survived
evolved spines. The spines would have
worked together with miniature tentacles to
help forams grab larger prey, Lowery says,
bolstering the idea that other single-celled
organisms also adapted their feeding style.
Eventually coccolith survivors picked up
photosynthesis again, revitalizing the ocean’s
food webs when light returned. Tiny, hungry
algae helped to save the seas. — Riley BlackA modern coccolith has holes that help with locomotion.© 2021 Scientific American
March 2021, Scientifi cAmerican.com 19FROM “ALGAL PLANKTON TURN TO HUNTING TO SURVIVE AND RECOVER FROM END-CRETACEOUS
IMPAC T DARKNE SS,”BY SAMANTHA J. GIBBS ET AL., INSCIENCE ADVANCES,VOL. 6, NO. 44; OCTOBER 30, 2020PALEOBIOLOGYPredatory
Algae
When the sun disappeared,
tiny coccoliths became huntersAn asteroid strike 66 million years ago not
only devastated the dinosaurs but almost
reset life in the oceans back to a primitive
soup of simple microorganisms. What pre-
vented ocean ecosystems from totally col-
lapsing, scientists hypothesize, may have
been shell-covered algae that could feed on
other organisms but maintained the ability
to photosynthesize. This skill would preserve
the foundation of the marine realm’s com-
plex food webs through a long dark spell.
The predatory plankton belonged to
a family of armored, algaelike organisms
called coccolithophores, or coccoliths. They
have been around for about 200 million
years, and many forms still bob along as
ocean plankton today. But their survival was
especially signifi cant in the wake of the mass
extinction at the end of the Cretaceous peri-
od, when debris from the asteroid’s impact
and wildfi re ash blotted out the sun for two
years. Life experienced a prolonged “impact
winter” when photosynthesis all but ceased.
“The food webs in the ocean have pho-
tosynthesis as their foundation, just like the
land, but in the ocean the photosynthesis
is carried out by microscopic bacteria and
algae,” says University of Southampton
paleontologist Samantha Gibbs, lead authorof a new study in Science Advances. Cocco-
liths were among these energy converters
in the Cretaceous, and about 90 percent of
coccolith species went extinct after impact.
Lacking light for their energy needs,
Gibbs says, “the handful of survivor species
were able to turn to food capture and inges-
tion.” Small holes in coccolith fossils indicate
that the survivors possessed whiplike fl agel-
la that let them move and stalk other organ-
isms. The researchers tracked hunter
algae’s prevalence in the fossil record and
modeled the organisms’ evolution to show
how they could have survived and adapted
to the sun’s disappearance—and then its
return, when they proliferated again.
Experts have long wondered how pho-
tosynthesis-using organisms such as coc-
coliths endured without sunlight. “This is a
really exciting fi nding that goes a long way
to explaining an apparent paradox in the
extinction,” says University of Texas at
Austin paleontologist Christopher Lowery,
who was not involved in the study.
The model may explain changes in other
organisms as well. Small creatures called
foraminifera, or forams, also took a hit from
the impact but persisted. They were
armored, too, and those that survived
evolved spines. The spines would have
worked together with miniature tentacles to
help forams grab larger prey, Lowery says,
bolstering the idea that other single-celled
organisms also adapted their feeding style.
Eventually coccolith survivors picked up
photosynthesis again, revitalizing the ocean’s
food webs when light returned. Tiny, hungry
algae helped to save the seas. — Riley BlackA modern coccolith has holes that help with locomotion.March 2021, ScientificAmerican.com 19FROM “ALGAL PLANKTON TURN TO HUNTING TO SURVIVE AND RECOVER FROM END-CRETACEOUS
IMPAC T DARKNE SS,”BY SAMANTHA J. GIBBS ET AL., INSCIENCE ADVANCES,VOL. 6, NO. 44; OCTOBER 30, 2020PALEOBIOLOGYPredatory
Algae
When the sun disappeared,
tiny coccoliths became huntersAn asteroid strike 66 million years ago not
only devastated the dinosaurs but almost
reset life in the oceans back to a primitive
soup of simple microorganisms. What pre-
vented ocean ecosystems from totally col-
lapsing, scientists hypothesize, may have
been shell-covered algae that could feed on
other organisms but maintained the ability
to photosynthesize. This skill would preserve
the foundation of the marine realm’s com-
plex food webs through a long dark spell.
The predatory plankton belonged to
a family of armored, algaelike organisms
called coccolithophores, or coccoliths. They
have been around for about 200 million
years, and many forms still bob along as
ocean plankton today. But their survival was
especially significant in the wake of the mass
extinction at the end of the Cretaceous peri-
od, when debris from the asteroid’s impact
and wildfire ash blotted out the sun for two
years. Life experienced a prolonged “impact
winter” when photosynthesis all but ceased.
“The food webs in the ocean have pho-
tosynthesis as their foundation, just like the
land, but in the ocean the photosynthesis
is carried out by microscopic bacteria and
algae,” says University of Southampton
paleontologist Samantha Gibbs, lead authorof a new study in Science Advances. Cocco-
liths were among these energy converters
in the Cretaceous, and about 90 percent of
coccolith species went extinct after impact.
Lacking light for their energy needs,
Gibbs says, “the handful of survivor species
were able to turn to food capture and inges-
tion.” Small holes in coccolith fossils indicate
that the survivors possessed whiplike flagel-
la that let them move and stalk other organ-
isms. The researchers tracked hunter
algae’s prevalence in the fossil record and
modeled the organisms’ evolution to show
how they could have survived and adapted
to the sun’s disappearance—and then its
return, when they proliferated again.
Experts have long wondered how pho-
tosynthesis-using organisms such as coc-
coliths endured without sunlight. “This is a
really exciting finding that goes a long way
to explaining an apparent paradox in the
extinction,” says University of Texas at
Austin paleontologist Christopher Lowery,
who was not involved in the study.
The model may explain changes in other
organisms as well. Small creatures called
foraminifera, or forams, also took a hit from
the impact but persisted. They were
armored, too, and those that survived
evolved spines. The spines would have
worked together with miniature tentacles to
help forams grab larger prey, Lowery says,
bolstering the idea that other single-celled
organisms also adapted their feeding style.
Eventually coccolith survivors picked up
photosynthesis again, revitalizing the ocean’s
food webs when light returned. Tiny, hungry
algae helped to save the seas. — Riley BlackA modern coccolith has holes that help with locomotion.sad0321Adva3p.indd 19 1/20/21 7:38 PMScientific American is a registered trademark of
Springer Nature America, Inc.Scientific American is a registered trademark
of Springer Nature America, InconeThirdNonBleed.indd 16 9/17/19 3:22 PMUntitled-2 1sad0321Adva3p.indd 19 1/21/21 11:13 AM1/21/21 11:38 AM© 2021 Scientific American