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(SEA OTTER COLONY); MIKELANE45 / DREAMSTIME (ARCTIC FOX); DANITA DELIMONT / GETTY SUZI ESZTERHAS / MINDEN PICTURES (MOM AND PUP); ROLF HICKER PHOTOGRAPHY / ALAMY
16 NAT GEO KIDS^ •^ AUGUST 2019 IMAGES (SEA OTTER ON SNOW). FOREVER HAPPY / SHUTTERSTOCK (GIANT PANDA, PAGES 18-19)
Sea otters
live in colonies
that can include
over a thousand
individuals.FIND OUT HOW YOU CAN
PROTECT THE PLANET.
natgeokids.com/SaveTheEarthWhen a group of sea otters in
the Pacific Ocean started suf-
fering from heart disease,
scientists were stumped. To
solve the mystery, they exam-
ined the animals in their
central California coastal
habitat. What they found was
a dangerous toxin, produced
by an explosion of algae, that
was sickening the otters.
“After we discovered the
toxin in otters, we made the
connection between blooms of
this algae and the otters’ heartconditions,” says Christine
Kreuder Johnson, a researcher
at the University of California,
Davis. “Thanks to the otters,
we knew about the extent of
the toxic algae in coastal
waters and could look into its
impact on other animals too.”
(Experts suspect environmental
conditions, such as change in
ocean temperature and nutri-
ent levels, were likely the cause
of the excess algae, but the
cause of what’s producing the
toxin is still a mystery.)Sea otters eat a lot—and
a lot of different foods—so
they’re more likely than
other animals to ingest
something dangerous. And
because otters don’t travel
much, scientists can keep a
close eye on odd behavior.
That’s why otters are called
indicator species—they’re
among the first to react to
environmental changes.
“Sea otters have helped us
solve several environmental
mysteries,” Johnson says.5
LIFE SAVERS
A PUP RESTS ON ITS
MOTHER’S TUMMY.