12 | WEDNESDAY, JULY 31, 2019 THE NEW YORK TIMES INTERNATIONAL EDITION
science
Few wonders of the sunless depths ap-
pear quite so ghoulish or improbable as
anglerfish, creatures that dangle biolu-
minescent lures in front of needlelike
teeth. They are fish that fish.
Typically, the rod of flesh extending
from the forehead glows at the tip. An-
glerfish can wiggle the lure to mimic liv-
ing bait. Most species can open their
mouths wide enough to devour prey
whole, using their fangs not only as dag-
gers but also as bars of a cage. Some can
open their jaws and stomachs wide
enough to trap victims much larger than
they are.
(This portrayal applies only to female
anglerfish. The males, with rare excep-
tions, are puny.)
Anglerfish came to the attention of
science in 1833, when a specimen of the
bizarre fish — a female — was found on
the shores of Greenland. Since then, sci-
entists have learned most of what they
know by pulling dead or dying speci-
mens from nets. Lifestyle clues have
been sparse.
That is changing. In the past two dec-
ades, deep-sea explorers have begun to
catch glimpses of the creatures in their
own habitats and have recorded with
video cameras a range of surprising be-
haviors. In a first, a recent expedition off
the Azores caught sight of a female and
her tiny parasitic mate locked in a pro-
creative embrace.
“It was amazing,” Theodore W.
Pietsch, an emeritus professor at the
University of Washington in Seattle and
a world authority on anglerfishes, said
of the video. “They’re glorious, wonder-
ful things that need our attention and
our protection.”
In 2014, Bruce H. Robison, a senior
marine biologist at the Monterey Bay
Aquarium Research Institute in Califor-
nia, caught sight of an anglerfish known
as the black seadevil while exploring the
deep bay. He managed to record min-
utes of its swimming.
“Instead of examining dead fish,
we’re now doing behavioral studies,” he
said in an interview. “It’s a significant
transition.”
Many kinds of anglerfish inhabit the
ocean. So far, scientists have identified
168 species. But most attention goes to
deep-sea varieties.
The new videos add otherworldly
drama and insights to a sparse but fasci-
nating body of existing knowledge. In
his 1964 book “Abyss,” Clarence P. Idyll,
a fisheries biologist at the University of
Miami, said the rod tips could glow in
yellows, yellow-greens, blue-greens and
oranges tinged with purple.
“Deep-sea creatures must find these
colored lights irresistible as they flicker
and flash faintly in the dark waters,” he
wrote.
Speciation has produced a great di-
versity of protruding lights and rods.
Some anglerfish have a long barbell ex-
tending from the lower jaw as well as a
rod above. One species, Lasiognathus
saccostoma, bears not only a movable
rod but extending from it a line, a float, a
lighted bait and three hooks. The hooks,
Dr. Idyll wrote, “are, alas, not actually
for catching prey.” They are simply or-
namental.
Anglerfish, he noted, are “rarely as
large as a man’s fist.” But one specimen,
from a depth of 2.2 miles off West Africa,
was a foot and a half long. It was also un-
usual in having its glowing bait conven-
iently located inside its enormous
mouth.
The largest known deep anglers are
the warty seadevils. The females typi-
cally run about two-and-a-half feet long,
and free-swimming males less than a
half inch.
The examination of stomach contents
has shown that anglers eat shrimplike
animals, squids, worms and lanternfish,
a common type of deep-sea fish with
large eyes and a highly developed visual
system that apparently can detect col-
ors.When an anglerfish suddenly opens
its giant mouth, Dr. Idyll wrote, the re-
sulting suction pulls in the luckless vic-
tim.
After the jaw slams shut, small teeth
on the floor of the mouth and throat de-
liver the meal to the fish’s belly.CAUGHT ON VIDEO
The first undersea video recordings of
the creatures were made in 1999 and
surprised researchers. Scientists from
the Woods Hole Oceanographic Institu-
tion on Cape Cod, Mass., had set up an
undersea observatory in the North Pa-cific between California and Hawaii,
more than three miles down.
A seven-foot-long tethered robot
named Jason was lowered to survey the
area. Soon, its operators were startled to
see a fish drifting in the bottom current
upside down, with its extremely longrod hanging downward in a graceful,
forward-arching curve. Unexpectedly,
they found two other fish similarly up-
ended.
Jon A. Moore, a fisheries biologist at
Florida Atlantic University, identified
the creatures as whipnose anglerfish, al-though of an unknown species. In a 2002
paper, he wrote that they apparently
were looking for prey by trolling over
the muddy seabed with glowing bait.
Visible just below the fish, he noted,
were “numerous small burrows.”
In an interview, Dr. Moore said the
video represented “the first time anyone
had seen” any kind of whipnose in its
own dark habitat. He added that despite
the intervening years, the question of
what the fish were pursuing on the Pa-
cific floor remained a mystery.
The Monterey research institute — in
Moss Landing, Calif., at the midpoint of
the bay shoreline — was established in
1987 by David Packard, the billionaire
co-founder of Hewlett-Packard and a
creator of Silicon Valley. It has built gen-
erations of increasingly smart, fast ro-
bots that probe the nearby waters.
In 2005, nearly a mile down in the wa-
ters off Monterey, institute scientists
were flying a tethered robot when they
tracked an angler for a record 24 min-
utes. The resulting paper, by Dr. Pietsch
and another University of Washington
scientist, detailed a series of behaviors,
from swimming bursts to long bouts of
drifting. Over all, they wrote, their ob-
servations supported the theory that
“these animals are lethargic, lie-and-
wait predators.”
The range of known behaviors grew
larger when institute scientists probed
seamount chains west of the Monterey
Canyon. Expeditions in 2002 and 2010
videotaped odd anglers with bulbous
bodies, shaggy lures and fins that the
fish used to walk along the rocky sea-
bed. The scientists speculated that
walking disturbed the seawater less
than swimming, reducing the chances of
startling nearby prey.
The newest video to go public was
made off the Azores by a research team
from the Rebikoff-Niggeler Foundation,
based on the island of Horta. In 2016, a
half-mile down, Kirsten and Joachim
Jakobsen were returning to the surface
in their submersible when they spotted
a female angler “resplendent with biolu-
minescent lights,” as Science magazine
described the fish. It was later identified
as a fanfin seadevil, a ghoul of the deep
with a bushy lure.
The team also videotaped a dwarf
male fused to her underside — a perma-
nent sperm donor. Males of that species
had never before been seen by humans.DENIZENS OF THE DEEP
Young male anglerfish face the chal-
lenge of finding mates in the ocean’s
vastness. They have large olfactory or-
gans, which suggests that suitors follow
a trail of pheromones. If courtship is suc-
cessful, the male fuses permanently to
the female, and their tissues and circula-
tory systems commingle.
In the case of the Azores discovery,
“the size of her belly indicates that she
was gravid,” or full of offspring, Kirsten
Jakobsen said in an email.
The foundation team was able to track
the pair for 25 minutes; what mesmer-
ized its members was not only the pro-
creative union but the halo of filaments
that radiated outward from the female’s
body, shimmering with points of light.
Dr. Pietsch, of the University of Wash-
ington, said the rays contain nerves and
may act like sensory antennae, alerting
the angler to nearby prey. “We’ve hy-
pothesized that they pick up vibrations,
like the whiskers of a cat,” he said.
He and a colleague in Germany are
trying to determine whether the shim-
mering lights in the rays are biolumines-
cent or were merely reflecting light from
the submersible. If the rays are glowing,
he said, “it would be really important.”
The new videos make clear — more so
than the old sketches and portraits —
that anglerfish look truly demonic. Why
the nightmarish appearance?
Dr. Robison noted that the exotic fea-
tures of anglerfish make perfect sense
as evolutionary adaptations to an icy,
dark world in which meals are few and
survival depends on cunning.
In the desert of the deep sea, he said,
“they have to take advantage of every
prey opportunity that comes by. That’s
why they have such huge mouths and
distensible stomachs: to take in a meal
that might have to last for months.”Ghoulish hunter in the oceans’ depths
NORBERT WU/MINDEN PICTURESThe anglerfish baits
a deadly trap with its
own brand of wormBY WILLIAM J. BROADA humpback anglerfish, a deep-sea species. The lure emerging from its head glows in the deep-ocean darkness and lures the anglerfish’s prey, which is then trapped in its jaws.A few years ago, researchers at Harvard
and Kaiser Permanente Northern Cali-
fornia had an inspired idea: Perhaps
they could use the wealth of personal
data in electronic health records to iden-
tify patients at high risk of getting in-
fected with H.I.V.
Doctors could use an algorithm to find
these patients and then steer them to a
daily pill to prevent infection, a strategy
known as pre-exposure prophylaxis, or
PrEP.
The scientists have succeeded. Their
results, they say, show that it is possible
to correctly identify men at high risk by
examining medical data already stored.
But the researchers know they must
tread delicately in using the software.
It’s one thing to have a computer find a
patient who is at risk for breast cancer.
But to have software that suggests a pa-
tient has unsafe sex too frequently and
risks H.I.V. infection — how should doc-
tors use such a tool?
And if they do, can they initiate a con-
versation about a patient’s sexual health
with understanding and delicacy?“This certainly could be an aid for
providers,” said Damon L. Jacobs, a
marriage and family counselor in New
York who takes PrEP and educates oth-
ers about it.
But a lot depends on the doctor: A cal-
culator that says a patient is at risk
“doesn’t mitigate the fact that providers
are often uncomfortable and clumsy
talking about sex,” he said.
And patients may well bristle. “Who’s
looking over my records? You think I’m
a slut? You want me to take an ‘anti-slut’
pill?” said Mr. Jacobs, musing about
how patients might react.
Clearly, doctors should not spring
such a result on patients, said Dr. Ellen
Wright Clayton, a professor of health
policy at Vanderbilt University. Instead,
she said, they should first ask patients if
they want their records reviewed by the
software.
The drug Truvada, made by Gilead,
was approved seven years ago for PrEP.
Taken daily, it appears to be almost com-
pletely effective in protecting users
against H.I.V. infection.
But just 35 percent of the 1.1 million
people who could benefit from the pillsuse them. And there are nearly 40,
new H.I.V. infections a year in the
United States.
The problem is especially acute
among black gay and bisexual men: In
their lifetimes, half will be infected with
H.I.V., said Dr. Julia Marcus of Kaiser
Permanente, a developer of the new al-
gorithm.
Use of PrEP has lagged for a number
of reasons. Until recently, insurers did
not always pay for the pills, which have
a list price of about $2,100 a month. And
patients do not always have regular doc-
tors who know them well enough to dis-
cuss H.I.V. risk.
For the most part, the onus has been
on patients to ask for PrEP, said Dr.
Douglas Krakower, leader of the Har-
vard group developing an algorithm.
“Clinicians are very busy and have lim-
ited time and tools to identify people
who may be at risk,” he said.
Software might spare them the effort.
“We intuitively felt like there were many
data elements in the electronic health
record that could predict risk,” Dr. Mar-
cus said. The challenge was to identify
which ones worked best.So the groups developed several dif-
ferent models, using electronic records
from 3.7 million uninfected patients at
Kaiser Permanente and 1.1 million pa-
tients at two Massachusetts medical
centers. Some models were simple: The
software looked at little more than sexu-
al orientation and history of sexually
transmitted diseases. But others were
more complex.
The scientists tested these models by
using them to review health records of
people who were free of H.I.V. infections
and asking if they could identify who
subsequently became infected.
The final Kaiser Permanente model
included 44 predictors and factors like
living in an area with a high incidence of
H.I.V., use of medications for erectile
dysfunction, number of positive tests for
urethral gonorrhea and a positive urine
test for methadone.
The software flagged 2.2 percent of
the patient group, correctly identifying
nearly half of the men who later became
infected. The Harvard group had similar
results with its model.
Dr. Marcus said that there was a real
need to identify patients at risk. Half thepatients at Kaiser Permanente North-
ern California who became infected said
they had not known about PrEP.
But the algorithm did not identify ev-
eryone at risk, Dr. Clayton noted. So, af-ter asking patients if they want the
screening, doctors will have to explain
that the test is not perfect and ask: “Are
there other things in your life that make
you more at risk?”Predictor of H.I.V. risk needs to be used with delicacy
JAMES STEINBERGBY GINA KOLATAРЕ
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