Sharks, Snakes and Experts
Walter Starck
For some reason Gray Reef Sharks in the central Pacific are especially
aggressive and a number of divers have been attacked. After
several unpleasant experiences there in the early 70's I was inspired
to come up with something which might deter them. This was the
banded wetsuit.
The banded wetsuit as an anti-shark device achieved some notoriety
and became a subject of controversy as to its effectiveness.
The story affords some interesting insights into the behavior
of both sharks and humans. It begins in Panama where Dr. Ira
Rubinoff of the Smithsonian Tropical Research Institute told me
how predatory Caribbean reef fishes held in large tanks with sea
snakes from the Pacific would try to eat the venomous snakes and
frequently die as a result. Pacific reef fishes, however, wouldn't
bother the snakes. There are no sea snakes in the Caribbean
so it appeared that fishes normally living together with the snakes
have learned to leave them alone.
Later in the western Pacific I noticed that the majority of sea
snake species had banded color patterns. I knew that banded
patterns were employed as warning coloration in various venomous
creatures thus the idea of a banded pattern to warn off sharks
was born. I first tried it in the Coral Sea on Gray Reef Sharks
(Carcharhinus amblyrhynchos). They exhibited notable
reticence to approach me nearly as close when wearing the banded
suit. Subsequently I used the banded suit for extensive diving
at Lord Howe Island, New Zealand, New Caledonia, the New Hebrides,
the Solomons, New Guinea and the Great Barrier Reef.

(Click for large view)
Left: Inspiration at hand.
Right: At Ontong Java.
Response to the suit varied with species. Reef Whitetips (Triaenodon
obesus) displayed little reaction showing their usual indifference
or mild curiosity towards a diver. Silvertips (C. albimarginatus)
and especially Grays were less prone to approach, the closeness
of approach was noticeably more distant and the frequency and
intensity of aggressive displays much less with the suit. In
a few instances the response to the suit was dramatic. At Lord
Howe on several occasions dozens of Galapagos Sharks (Carcharhinus
galapagensis) surrounding divers in plain suits at close range
immediately moved away when the banded suit appeared. On various
occasions elsewhere, particularly aggressive Grey Reef Sharks
quickly dispersed when approached with the banded suit.
After the banded suit appeared in articles, books and films several
other divers and researchers reportedly tried experiments with
the idea and reported negative results. My experience based
on thousands of hours underwater over a wide geographic area both
with and without the suit clearly indicates a decided effect on
the curiosity and aggressiveness of Gray Reef Sharks in particular
and to a less noticeable degree other reef sharks. So, how to
explain the difference in opinion, all expert of course.
First let's consider the matter of sharks and sea snakes. Sharks
are not afraid of sea snakes they just tend not to bother them.
This is not absolute. Tiger sharks in some areas are reported
to regularly eat them but then tiger sharks also have been known
to eat highly venomous stonefish, poisonous puffers, bottles,
tins, a ships logbook and a wooden tom-tom. On the other hand
the common reef sharks are much smaller species, perhaps thus
more susceptible to a snake bite, and seem normally not to eat
them. This immunity is in turn reflected in the behavior of
sea snakes toward sharks, whom they tend to ignore. I have seen
a sea snake swim slowly and steadily with apparent nonchalance
through a feeding frenzy of Gray Reef Sharks. Though sharks
may not readily attack sea snakes, insofar as a banded pattern
resembles a snake there is no reason to expect sharks to exhibit
fear of it.
The problem though is more complex than that. Sharks have sophisticated
sensory systems which must also be considered. They have a contrast
enhancing mechanism in their visual system which enables them
to see farther underwater than we can. The tradeoff however,
is that a high contrast black and white pattern may appear to
them as disconnected objects against a contrasting background
without the finer degrees of shading which join the pattern into
a whole.
Sharks also have excellent receptors for sound and smell. In
addition to the sounds of bubbles and compressed air coming through
a regulator they can hear swimming sounds and even heartbeats.
Their sense of smell is especially acute though what they detect
of humans in that regard is unknown. Their most unusual sense,
however, is their ability to detect the weak electrical fields
generated by living creatures. This sense is so acute they can
even use it to respond to the minute current generated by their
movement through the Earth's magnetic field. In effect this
gives them an in-built fluxgate compass, something we have only
recently found a way to do with sophisticated electronics.

A scuba diver must present a confusing sensory picture to a shark.
Swimming sounds, heartbeat, electrical fields and perhaps smell
may be more or less familiar but shape, bubbles and regulator
noises are not like anything normal. Add to this a high contrast
pattern which presents the appearance of a disjointed jumble of
bits moving in strange ways and you greatly add to the confusion.
That this pattern resembles that of highly venomous creatures
the sharks usually leave alone can not but help. The natural
response to all this is curiosity moderated by caution. Depending
on whether the diver is relatively inactive or conversely moves
towards the shark the response may range from curiosity to flight.
Of the negative results reported regarding banded suit experiments
all involved misperceptions of either what to do or what to expect.
One used yellow and black bands which of course reduces the
contrast of the pattern. Then, not noticing any dramatic effect
on the behavior of sharks attracted by spearing fish he decided
the banded pattern had no effect. Another stuffed a banded suit
with fish and not surprisingly sharks soon took it. The absence
of any of the bubbles, motions, sounds, smells, or electrical
fields associated with a diver were apparently not considered
as relevant. The most recent such pseudo-experiment of which
I am aware consisted of using bait to attract Whitetip Reef Sharks
to a diver wearing a banded suit. The effect was apparently
about like that one would expect from wearing a gorilla suit while
passing out candy at a children's birthday party.
In each case a brief poorly conceived trial was sufficient to
convince these individuals that I was wrong and they were right.
This phenomena is common enough to have a name. It's called
the NIH factor. To persons familiar with the world of scientific
research NIH brings to mind the National Institutes of Health,
the U.S. government agency which is probably the single largest
disburser in the world of funds for scientific research. The
NIH to which I refer, however, is not that well known one but
rather the lesser known Not Invented Here factor.
The greatest resistance to new ideas or inventions seems to come
from those who are themselves already established in that field,
unless of course, they were the ones to come up with them. The
simpler and more obvious the idea is, the greater
the resistance. The principle is simple. If something that
simple had any merit I as an expert would have thought of of it.
Since I didn't, it obviously has no validity. Now that I have
dismissed the experts, including myself, who are you to believe?
The island peoples of the Pacific have lived in intimate relationship
with the sea for thousands of years and know much about that realm
we have yet to learn. At Mota Lava in the Banks Islands are
a people who have a legend about how the sea snake once saved
all the fish in the sea by driving away the shark who was threatening
to eat them. This legend is commemorated in a sea snake dance
in which the dancers paint themselves with black and white bands.


(Click for large view)
Sea snake dance, Mota Lava.
A few years ago the king of Tonga on a visit to Australia was
reported as saying that his people did not have to worry about
shark attack as people do here. He said they just painted themselves
with black and white stripes to ward off sharks. A similar tradition
has also been reported from Samoa.
If you still remain dubious about any human opinion let nature
have the last word. There is one edible, non-venomous, un-armored,
bite- sized creature which has chosen to spend its whole life
inches in front of a sharks mouth. Have a look sometime at the
color pattern of a pilot fish (Naucrates ductor).
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