By Dan Kirk
The other night, during the lunar eclipse in Cancer, we sat next to a fire on the beach during the highest tides, or the “King Tides” of the year. There were crab shells all around, and we joked that the eclipse was summoning the crabs (crab is the astrological symbol for the zodiac sign of Cancer). Looking into the fire, then back out into the water, then up at the sky, then at my dog, I felt surrounded by beauty and mystery. I wanted to do something about it, I wanted more. The idea of running into the dark, loud, lapping ocean was becoming more and more like a risk I wanted to take, or an experience I wanted to have. There was only one thing stopping me. It wasn’t the cold, it wasn’t the strong tide, it wasn’t the darkness; it was sharks. This article is about the Great White Shark, Carcharodon carcharias.
Instead of continuing in the direction of how scary sharks are, I’d like to instead begin by sharing that sharks are older than dinosaurs…by about 200 million years. When you ask a large group of 6th graders what their favorite animal is, I would put a dollar down that at least one student would say the Megalodon, which is an extinct species from roughly 23 million years ago. Some say, and I’d agree, that sharks are one of evolution’s “greatest success stories”. They have evolved to acquire six acute senses: taste, smell, hearing, touch, sight and electromagnetism. All of their senses are strong. For example, their sense of smell is so strong that if there was a drop of…beet juice in the equivalent of 10 billion drops of water, a great white shark could detect it (that’s about one drop in an olympic sized swimming pool). Their sense of smell is legendary, especially if you replace the example of a beet juice drop in water with a drop of blood.
The sense of electromagnetism means that they can sense an electrical field. All living organisms generate electric fields around their bodies, but only some organisms are able to sense them. Sharks, rays, and skates, is one group of animals called the Elasmobranchii that possess electroreceptors, allowing them to detect electric fields.The great white shark’s nose is lined with cells called the Ampullae of Lorenzini that can feel the power and direction of electrical currents. These receptor cells are stimulated by the electric current and send signals to the brain.
At the end of the day, much of what we fear as a society is cultivated by our culture and media, but also by very real power dynamics, such as the fact that great white sharks weigh literally a ton and have about 300 teeth in seven layers. But what can we say about our own species? The machines we use daily? And so forth. At the end of the day, or the next day, rather, I ended up going surfing without a trace of shark in my mind nor at my feet.
Read more about other sharks in the Bay Area in other What’s In Your Watershed articles in our newsletter!