Afraid to go into the water?

With around 66 species of shark swimming off the New Zealand coastline, and dozens regularly being sighted by fishers, swimmers and surfers, it’s a wonder they still have the power to stop us in our tracks.

There could be several reasons for the obsession.

One, they are beautiful.

Sharks are sleek, their fusiform bodies taper at both ends with such limited drag they would seem capable of gliding through air as well as water. In relaxed mode, they slide through the sea with so little effort, a mere waft of the tail from time to time.

Two, their sheer menace.

Even the most benign of the species, such as the rig shark or the spiny dogfish, look like they could eat any other living creature in a heartbeat. These elasmobranch fish exude an air that announces “apex predator”. In their domain, the food chain ends with sharks. They are literally and figuratively coldblooded.

Three, their sensory powers.

Some species can detect as little as one part per million of blood in seawater. With a tissue called patetum lucidum behind their retinas, they can see in the darkest waters.

When a shark is spotted, it’s best to

leave the water.

It’s believed they can hear prey many kilometres away and, further, a lateral line helps detect water speed and nearby pressure changes.

Four, their teeth.

Once seen, never forgotten. Rows and rows of serrated-edged teeth are constantly being replaced from the inside of the mouth like a conveyor belt of carnage. When a shark loses a front tooth, another moves effortlessly into its place.

Five, our vulnerability.

This is probably the biggest factor.

While most phobias can be reasoned with and overcome, a fear of sharks is innately impressed in us because we know our survival in the sea is their choice, not ours. Understanding has improved in recent years and many people understand sharks need protection and are rarely a danger to humans. However, the advice remains, when a shark is spotted, it’s best to leave the water.

About 400,000 awestruck visitors who go to Kelly Tarlton’s Aquarium each year are not there for the penguins, delightful as they are. They are there to look into the unflinching eyes of a malevolent killing machine, largely — but not entirely or unreasonably — built up in our own imaginations. —

Herald on Sunday