By
Ms. Weisberger, Sr. Writer 12/21/18 LiveScience
A
Costa Rican river anole recently demonstrated an ability that was previously
unknown in lizards. – via Herp Digest
Credit:
Smithsonian Channel
and
on "Laws of the Lizard" airs Dec. 26 at 8 p.m. (local time)
on the Smithsonian Channel.
Lizards
can't breathe underwater — or can they?
Footage
of a river anole that was recently filmed in Costa Rica revealed that the
species — Anolis oxylophus — possesses a highly unusual ability. The anoles
breathe stored oxygen while underwater, something that has never been seen or
documented before in lizards.
Biologists
and filmmakers Neil Losin and Nate Dappen caught this remarkable behavior while
shooting the anole-centric documentary "Laws
of the Lizard" for the Smithsonian Channel. Costa Rican
river anoles were known for disappearing underwater for minutes at a time, but
scientists thought that the elusive reptiles were just very good at holding
their breath. However, the truth turned out to be far stranger, as Losin and
Dappen found a previously unknown behavior in the group.
For
more than a year, the filmmakers traveled to locations around the world to film
"Laws of the Lizard," which tells the surprisingly complex story of
anoles, a lizard group found across the American tropics. Anoles are small and
colorful, and they are equally at home across a diverse range of habitats, from
rainforests to suburban backyards.
Though
these lizards may seem common and uninteresting, scientists are fascinated by
the creatures, publishing thousands of studies on anoles over the past 50
years, Losin told Live Science. And because anoles are so well-researched, they
present scientists with the chance to ask highly nuanced questions about
anoles' evolution,
biology and behavior, Dappen explained.
One
of those deep-diving questions was about the diving Costa Rican river anole and
what exactly was happening after they jumped into the water, remaining there
for as long as 15 minutes. Herpetologist Luke Mahler, an assistant professor of
ecology and evolutionary biology at the University of Toronto, urged the
filmmakers to look closely at their underwater footage when they filmed the
anoles, to see if they could identify any clues that would explain what the
river anoles were doing.
While
Dappen and Losin didn't see anything out of the ordinary when they first
reviewed the video, they watched it more closely after they returned to the
United States. That was when they noticed something remarkable.
"We
saw this re-breathing behavior that hadn't been documented or described
before," Losin said.
The
river anole caught on video recycled stored oxygen, visible as a bubble grew
and shrank on its head.
Credit:
Smithsonian Channel
What
they observed was astounding. As a submerged female anole crouched on the river
bottom for nearly 10 minutes, a tiny bubble repeatedly expanded and contracted
at the top of her head. The lizard appeared to be recycling her air, much as a human
diver would draw on oxygen from a tank.
Presumably,
re-breathing stored air would enable river anoles to remain underwater long
enough for them to outwait threats on land, Dappen explained. Drawing on air
caches is known to occur in some
invertebrates, such as diving
bell spiders and diving beetles, but this may be the only
example of re-breathing in land animals that have backbones, Losin said.
How
the river anoles accomplish this feat is still uncertain, but Mahler and his
colleagues are currently investigating the mechanics of the behavior, Losin
told Live Science.
"It
demonstrates one of the things that biologists often find, which is that
there's so much we don't know about nature," Dappen said.
By
showcasing this anole species — and its numerous
cousins across the Americas — "Laws of the Lizards"
may help viewers finally understand why scientists think these lizards are so
special.
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