Swimming With Sharks

by wjw on January 27, 2016

nurseAnother photo by Troy, this of a nurse shark taking a nap under a piece of sheltering coral.  Contrary to myth, sharks do in fact sleep, though sometimes it’s hard to tell, because they can’t close their eyes.

The shark’s man-eating reputation, despite what you’ve seen on Shark Week, is ridiculously exaggerated.  People just don’t look like anything a shark would want to eat, and besides, we all taste of neoprene.

On this last trip sharks were always cruising around, so many that I got bored with taking their pictures.  They clearly were less interested in us as a tasty food item, than as something that might scare up something they might want to eat.

On one night dive, I dropped off the boat and looked straight down to see what looked like three nurse sharks chasing each other’s tails.  Which they were in fact doing, possibly under the impression that there was something in the vicinity to eat.  They looked like some strange pinwheel-based art installation, the more so because nurse sharks have an eerie, fluid, cartilaginous movement that make it seem as if they have no bones at all.  (Which, technically I suppose, they don’t.)  They have an odd resemblance to flapping flags.

They had moved off by the time I got to the bottom, but sharks were a constant annoyance for the rest of the dive.  Sharks may not be the brightest fish in the pond— that would be the octopods—  but they have learned that flashlights will point out fish that might serve as a light collation.  Jacks, another smart predator fish known as trevally Down Under, have learned the same thing.  So on that dive, whenever I tried to view something, a jack or a shark would barge into the picture in hopes of finding a tidbit.  Often the sharks would be close enough for me to stroke them, and some of them seemed to enjoy it.

Their skin is very rough and sandpapery, FYI.

So far as I know, I only found one food item for these freeloaders, and that was by accident.  I was concentrating on something else, and my flashlight was casually pointing off over my right shoulder.  It picked out a fish— all I know is that it was orange— and then Boom!, a jack dashed in and ate it.

One of the ladies of our company had found an eel, and was setting up to take a photo of it, when a shark charged in, knocked her clean out of the way, and gobbled up the eel.

“Did you at least get the picture?” I asked.

“No, I was too startled.”

Pity.  She could have sold the picture to Shark Week.

 

Phil Koop January 28, 2016 at 8:42 am

“Their skin is very rough and sandpapery …”

That’s because it’s covered in teeth! Nowadays these seem to be called “placoid scales”, but they used to be called “dermal denticles” (= “little teeth on the skin.”)

Contra “mythbusters”, shark skin has actually been used as sandpaper at some points in history.

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