IT'S SHARK WEEK, AND THIS IS YOUR "DAILY BITE."

THERE HAVE BEEN SOME INCREDIBLE DISCOVERIES

IN THE DEEP BLUE SEA SINCE LAST YEAR,

AND GREAT WHITE SHARKS HAVE BROUGHT US

SOME OF THE MOST JAW-DROPPING,

FROM MILLIONS OF YEARS AGO, RUBBING FINS WITH THE MEG...

TO BREACHING ALL NEW HEIGHTS THIS YEAR.

THIS APEX SPECIES IS A FORMIDABLE PREDATOR,

AND WE'RE NOW OBSERVING NEW STRATEGIES

IN THEIR ATTACK ARSENAL.

ONE OF THEIR MOST RECENTLY DISCOVERED TACTICS IS KELP.

SEALS TEND TO FEEL SAFE HANGING AROUND A PROTECTIVE KELP FOREST,

BUT RECENT RESEARCH FROM THE UNIVERSITY OF MIAMI

ACTUALLY SHOWS THEY HAVE REDUCED CORTISOL LEVELS

WHEN THEY AREN'T WORRIED ABOUT BECOMING LUNCH.

BUT RESEARCHERS INSIDE AFRICA

HAVE SPOTTED WHITE SHARKS LURKING IN KELP.

WITH THE SEALS' GUARDS DOWN,

THESE HUNTERS CAN USE IT AS A SORT OF CAMOUFLAGE

AS THEY STALK OUT THEIR UNSUSPECTING PREY.

AND THERE'S EVEN NEW PROOF THAT SUGGESTS THE GREAT WHITE'S

HUNTING ABILITIES HAVE BEEN SPOT-ON

FOR A GOOD 11 MILLION YEARS OR SO.

NEW FOSSIL DATING RECENTLY REVISED THE DATE

OF MEGALODON'S EXTINCTION

FROM 2.6 MILLION YEARS AGO TO 3.6 MILLION YEARS AGO --

RIGHT BACK TO WHEN GREAT WHITE SHARKS

WERE ALSO ROAMING THE OCEANS.

IT'S POSSIBLE THAT GREAT WHITE SHARKS

LITERALLY STARVED THE MEG INTO EXTINCTION

BY OUT-HUNTING IT.

NOW, THE ABSOLUTE COOLEST HUNTING TACTICS

PROBABLY GO TO THE BREACHING GREAT WHITE SHARKS

OF SOUTH AFRICA.

THE WORLD GOT ITS FIRST GLIMPSE OF THE JAW-INSPIRING BEASTS

BACK IN 2001

WHEN "SHARK WEEK" DIRECTOR JEFF KURR

CAPTURED THE PHENOMENON IN SOUTH AFRICA'S SEAL ISLAND.

WHAT'S REALLY INCREDIBLE IS THE SHEER SPEED

THAT GREAT WHITES ARE ABLE TO ACHIEVE

TO PROPEL THEIR ONE-TON BODIES

THROUGH THE SURFACE AND SNATCH UP THE SEALS.

THE RESULTS ARE JUST TERRIFYINGLY BEAUTIFUL.

UNFORTUNATELY, THE TWO-DECADE-LONG STUDY

THAT BROUGHT US YEARS OF AIR JAWS

HAS DISCOVERED THOSE ACROBATIC SHARKS

ARE DISAPPEARING FROM SOUTH AFRICA.

DR. NEIL HAMMERSCHLAG AND CHRIS FALLOWS

HAVE DOCUMENTED OVER 8,000 SIGHTINGS

SINCE THE YEAR 2000.

AND SOMEWHERE AROUND 2015,

THE NUMBERS DROPPED OFF DRAMATICALLY.

THINGS GOT EVEN QUIETER ON THE SURFACE IN 2017

WHEN THEY BEGAN DISAPPEARING ENTIRELY FOR MONTHS AT A TIME.

MY FRIEND DR. NEIL HAMMERSCHLAG

EXPLAINED HIS FINDINGS IN A NEWLY PUBLISHED PAPER

WITH AN EXCITING TWIST AT THE END.

WE KNOW THAT MANY SHARK POPULATIONS ACROSS THE GLOBE

ARE DECLINING, WHICH RAISES A REALLY IMPORTANT QUESTION.

WHAT ARE THE ECOSYSTEM CONSEQUENCES?

WHAT HAPPENS WHEN AN APEX PREDATOR

DISAPPEARS FROM AN AREA?

AND UNFORTUNATELY, TO THIS DAY,

TRYING TO OBTAIN THAT TYPE OF DATA HAS BEEN REALLY DIFFICULT

BECAUSE MOST STUDIES ARE SHORT-TERM.

HOWEVER, A LONG-TERM STUDY

AND COLLABORATION BETWEEN CHRIS FALLOWS AND I

REVEALED SOME REALLY NEW, EXCITING DATA

THAT'S HELPED PROVIDE INSIGHTS

INTO HOW AN ECOSYSTEM MIGHT CHANGE

FOLLOWING THE LOSS OF AN APEX PREDATORY SHARK.

IT'S CRAZY TO THINK THIS PLACE

THAT WAS FAMOUS FOR BREACHING GREAT WHITE SHARKS

NOW IS VOID OF GREAT WHITES.

BUT IN THE ABSENCE OF GREAT WHITE SHARKS,

WE DOCUMENTED SOMETHING THAT WE COULDN'T PREDICT --

ANOTHER APEX PREDATOR MOVING IN.

THE SEVENGILL SHARKS.

SEVENGILL SHARKS RESEMBLE PREHISTORIC SHARKS,

HAVING SEVEN GILLS INSTEAD OF THE NORMAL FIVE

THAT MANY MODERN-DAY SHARKS HAVE.

IN THAT PART OF THE WORLD, IN FALSE BAY,

SEVENGILLS WERE KNOWN TO AGGREGATE

NEARLY 20 KILOMETERS AWAY IN KELP FORESTS.

WE HAD THOUGHT THAT ONE OF THE REASONS THAT THE SEVENGILLS

WERE HANGING OUT IN THESE KELP FORESTS

IS BECAUSE THEY PROVIDED A REFUGE TO GREAT WHITES,

BECAUSE OTHER THAN GREAT WHITE SHARKS,

THESE SEVENGILLS DON'T ACTUALLY HAVE ANY NATURAL PREDATORS.

AND THE THOUGHT IS WHEN THE WHITE SHARKS HAVE LEFT,

THESE SEVENGILLS ARE ABLE TO MOVE TO SEAL ISLAND

AND TAKE ADVANTAGE OF THE VOID LEFT BEHIND

BY THE ABSENCE AND DISAPPEARANCE OF WHITE SHARKS.

WHAT THIS LONG-TERM STUDY REALLY SHOWED

IS THAT ECOSYSTEMS ARE COMPLEX,

AND WITHOUT AN APEX PREDATOR LIKE THE GREAT WHITE,

THE SYSTEM CHANGES.

AND FOR THE FIRST TIME IN 20 YEARS,

WE SAW THE EMERGENCE OF THIS OTHER APEX PREDATOR

MOVE INTO THE AREA -- SOMETHING THAT WE COULDN'T HAVE PREDICTED.

WE DON'T KNOW WHY THE GREAT WHITE SHARKS DISAPPEARED

OR WHERE THEY'VE GONE, HOWEVER, WHAT I CAN TELL YOU

IS WE'VE DOCUMENTED A NEW SPOT IN SOUTH AFRICA

THAT IS A GREAT WHITE SHARK HUNTING HOT SPOT.

WE WERE ABLE TO GO THERE

AND FILM FOR THIS YEAR'S "SHARK WEEK"

IN A SHOW CALLED "AIR JAWS STRIKES BACK."

AND AT THIS SITE, WE'VE SEEN SOME INCREDIBLE,

NEW HUNTING BEHAVIORS OF WHITE SHARKS

THAT HAVE CHANGED THE WAY WE LOOK AT SHARK/SEAL INTERACTIONS.

THE GREAT WHITE SHARK DISCOVERIES THIS YEAR

HAVE ONLY JUST TAPPED THE SURFACE

OF WHAT WE KNOW ABOUT THESE LIVING DINOSAURS.

"SHARK WEEK" SCIENTISTS HAVE UNCOVERED SO MUCH MORE,

LIKE THE REAPPEARANCE OF THE LARGEST GREAT WHITE SHARK

ON RECORD -- "DEEP BLUE"...

[ INDISTINCT SHOUTING ]

...AND SOME NEVER-BEFORE-SEEN PREDATION

IN SECRET HUNTING GROUNDS AROUND GUADALUPE.

STICK WITH US ALL "SHARK WEEK" LONG

AS WE CONTINUE TO BRING YOU THE COOLEST DISCOVERIES IN SHARK.

IN THE NEXT EPISODE OF THE "DAILY BITE,"

WE'RE GONNA CATCH UP WITH THE FASTEST SHARKS IN THE OCEAN

AND THEIR RACE AGAINST EXTINCTION.