The white tip reef shark is commonly found in the tropical reefs of
the world. This shark has white tips on its dorsal and tail fin, a blunt
snout and distinctive nasal flaps. It is inoffensive unless provoked and at
times falls prey to larger sharks. Humans have long tried to emulate the
sleek streamlined design of the shark, in boat hulls, submarines and even
torpedoes which have a similar outline to the standard shark.
Photo: Genevieve Johnson
October 25, 2000
Snorkeling a Surge Channel with Sharks
This is Genevieve Johnson talking to you from the Odyssey in the central
equatorial pacific. The Odyssey crew is always enthusiastic to get into the
water, whether to snorkel or dive we take every opportunity to explore this
universe. Today some of the crew went snorkeling along the coral reef flats
of Christmas Island.
Different depths support different habitats, each with its own
distinctive and diverse ecosystem of living organisms. The changes in
species according to depth, light and temperature was clear as we made our
way outward over the reef, which gradually sloped downward toward open
ocean, where it finally dropped off altogether.
We entered a surge channel, an area close to 20 feet deep, penetrating the
reef edge. These channel systems carry the flow of water from the reef flats
into the open sea.
It was as we were enjoying the luxuriant display of
corals on the steep slopes, which played host to countless brightly colored
fish, that the first unmistakable silhouette cruised just beyond our clear
range of visibility. With a rapid pulse and heightened sense of awareness,
we drifted in the channel and were soon surrounded by 4 or 5 small sharks.
We watched them slowly circle, the effortless grace of their movements
belying the difficulty of moving through water, a medium 1,000 times heavier
or denser than an equal volume of our own medium, air. Meanwhile we were
working hard to overcome the current sweeping us towards the sea.
The appearance of a shark can be unnerving, as they stare glassy eyed and
expressionless, their intentions are difficult for humans to interpret. As
far as we could tell, these beautiful animals appeared undisturbed by our
presence, circumstances that made it possible for us to observe them in
their natural habitat at quite close range. We realized that we were in fact
in the midst of at least 3 different species of reef shark, the Black tip,
White tip and Grey reef shark.
The black and the white tip are among the most frequently encountered sharks
on reef flats, and appear to be relatively inoffensive and easily
frightened. The Grey reef shark is an animal that typically inhabits the
steeper outer reef slopes. This species is more curious, territorial and has
been known to be aggressive toward humans, although this was never apparent
Some shark species undoubtedly attack humans, but when common sense
prevails, it is clearly us who are intruding into their realm.
Log by Genevieve Johnson
| Back |