Dive Pacific 175 Dec2020 Jan 2021

Tiny animals and their
critical importance on
entire oceanic food webs
By Jean-Michel Cousteau and Holly Lohuis
Ocean Futures Society www.oceanfutures.org
There is an inner galaxy of alien looking organisms on our own planet. Just night dive in open water
with a bright light and witness for yourself the water column coming alive with all different forms of
gelatinous plants and animals, referred to as plankton. It is indeed an unknown world to most of us,
a world of wandering, drifting plants and animals, which provide the base of the very complex and
extremely productive oceanic food web on which we all depend in so many important ways.
The word plankton comes from
the Greek, planktos, means to
wander, or drift. These plants and
animals make up a tremendous
amount of the biomass in our oceans,
yet the significance of how they
influence key planetary functions is
only being appreciated today as we
are documenting major changes in
our oceans.
While many of these mysterious
gelatinous organisms provide
important opportunities to study the
link between their abundance and
the health of our oceans, there are
many things we do know about their
importance.
…Every other breath we take is a gift from the sea…
Phyto (plant) plankton
Phytoplankton, plant plankton
thrive in nutrient rich waters and
are generally found in the sunlit
waters of aquatic environments. Like
terrestrial plants, phytoplankton
contain chlorophyll and require
sunlight in order to live and grow.
Through the process of photosynthesis,
phytoplankton take in CO 2
and release oxygen. In fact, as much
as 50% of our oxygen comes from
phytoplankton. We can think of them
as every other breath we take as a
gift from the sea. They are one of the
world’s most important producers of
oxygen and they provide important
food for the first order of consumers
in the aquatic trophic food web,
zooplankton.
Plankton participate in the largest migration on the planet which
happens under the cover of darkness every single night
Zoo (animal) plankton
Many zooplankton, or animal
plankton, are grazers, filtering the
planktonic soup of phytoplankton
and other floating organic material.
These animals participate in the
largest migration on the planet which
happens under the cover of darkness
every single day. At night trillions of
tiny plankton move from the deep
scattered layer well over 300m deep
towards the surface to feed. Come
early morning hours, they then dive
down to escape hungry mouths from
above. So even though plankton
are considered wanders, living a
life adrift in the open ocean, they
actually make an amazing vertical
movement every single day.
The richness of our seas is directly
related to abundance and diversity
of these drifting plants and animals.
They not only provide the base of a
rich web of life in the oceans, they
are even preyed upon by the largest
Inset Photo credit: Richard Murphy, PhD @Ocean Futures Society
www.dive-pacific.com 17