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modicum of skills, good breathing technique and luck, divers
may observe cleaning behavior — a fascinating symbiotic
arrangement between enormous manta rays and tiny wrasses.
Generally, if conducted in a small group of participants who
minimize their silhouettes by trying to blend in with reef cover,
staying low, keeping movement to a minimum, breathing
slowly, leaving an open passage for the mantas to approach and
depart, and allowing time for the manta rays to become used
to the bubbles, the cleaning phenomenon can be observed.
The normally wary manta rays may eventually overcome
their predator-avoidance instincts and become accepting of
the intruders’ presence to be relieved of parasites. But should
another boatload of divers drop in on the cleaning station
while the first group remains motionless and respectful of the
animals’ comfort level — as happens all too frequently in the
Maldives and Indonesia — then the mantas will bolt for the
blue and keep a distance from the cleaning station.
Some might conjecture that the mantas could go to another
cleaning station unknown to divers; that may be true, but it
fails to consider the caloric needs of the wrasses that perform
the cleaning service. If they cannot feed on the parasites
brought to them by large manta ray hosts because divers keep
the mantas away from those cleaning stations, do the wrasses
eventually starve and die? As most fish are territorial, it seems
unlikely that small wrasses forced to migrate from their
cleaning station due to diver pressure would be welcomed by
the wrasses established at another cleaning station.
When it comes to encountering cryptic critters, invasive
intrusion is a given. Pygmy-seahorse fascination is a well-known
scenario on dive boats. Speculations about whether constant
intrusion, lights or photography has a detrimental effect upon
the diminutive members of the seahorse family are legion. On
any trip within the pygmy seahorse’s range, it is inevitable that
a dive guide will indicate one using a pointer stick, a magnifying
glass or his fingers to identify a quarter-inch seahorse hunkered
down in the branches of a gorgonian sea fan. It is a rare
situation when the guide, in the process of doing what is
expected, does not touch the gorgonian to make the flowerlike
polyps retract to improve the view of the seahorse. The effect of
this intrusive custom on the pygmy seahorse is obvious, but the
overlooked effect is that the polyps retract a lot more than they
naturally would, and when the polyps retract the coral cannot
feed. Furthermore, these human interactions may obliterate the
protective slime that covers the sea fan, possibly weakening it
and making it susceptible to disease.
Even snorkeling can have an observer effect, as I’m often
reminded when exploring certain inshore reefs of the Red
Sea. There is a shallow bay where tourists are taken daily on
a dozen or more safari boats, each carrying as many as two
dozen vacationers, to have a snorkel experience among the
bay’s corals and fish and watch green sea turtles feeding on
seagrasses in the shallows near the shore. It is not uncommon
to see more than 100 people spread out across the bay at the
same time. While they are told in briefings not to stand on or
touch the corals or come in contact with the sea turtles, with
so many people the exceptions occur daily, and the obvious
transgressors behave appallingly. When the turtles are left
alone, they feed on seagrass for long stretches of time, surface
to breathe and continue all day long; when the turtles are
disturbed, they move off with slow but deliberate speed.
Another unfortunate and not-infrequent situation in the
region occurs when the area’s sole dugong is in the bay, also
feeding upon seagrasses, and the general alarm is raised to
the throng of tourists, who erupt in a cacophony of screams
and shrieks. This dugong, known locally as Dyson, behaves
uncharacteristically for a dugong, a species that’s generally
elusive and retiring. Dyson is tolerant toward humans
intruding in his feeding areas, yet even Dyson has his limits.
What starts off as a genuine desire to observe a relatively rare,
large, charismatic and harmless aquatic mammal in its natural
environment degenerates quickly into a mob scene straight out
of a horror film. Rather than keeping a respectful distance and
floating passively above the animal as it feeds rather obliviously
15 to 20 feet below, snorkelers kick their fins and paddle
furiously, pushing past each other, kicking, elbowing, clawing and
even climbing over one another to be directly above the animal
or next to it when it has to surface for air.
The dugong uproots and munches on seagrass stalks while
spitting out billowing plumes of sand as it makes furrows
in the soft seabed. A dugong’s strictly seagrass diet requires
an inordinate amount of feeding, as seagrass is modest in
nutrition. Thus, dugongs, like their terrestrial cousins the
elephants, need to eat constantly to thrive.
When humans motivated by excitement or a lamentable need
to show off begin dive-bombing the feeding dugong (or trying
to touch or grab or ride it) and crowding it when it comes to
the surface to breathe, its behavior changes. Dyson is not only
harassed, he is actively pursued and disturbed to the point that he
can no longer feed. The eventual outcome is that Dyson departs
the bay, swimming away forcefully and leaving shouting, deluded
humans high-fiving in its wake. These snorkelers pushed the act
of observation into an act of harassment, and the result for the
dugong is that he cannot feed where he needs to feed and must
expend precious energy searching for food where he can feed on
it in peace — or die trying.
The possibility of interacting with sea life is perhaps the
most irresistible and addictive aspect of going into the sea,
but we have to accept that every action we take in the sea
will likely have consequences for the life there. This is an
unavoidable aspect of submerging ourselves in a world of
which we are not naturally a part. Each individual must decide
what kind of impact he or she is prepared to live with.
In many places, the animals most likely to interact with divers
are marine mammals. This is not as common an occurrence
as it might be because laws in many countries forbid humans
from getting close to marine mammals, particularly whales
