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Needcoffee’s Shark Week: Day Four

We continue our shark expedition today with five more fascinating fish! And to help us on our journey today is Richard Ellis’ The Book of Sharks. This book is a lovely comprehensive work on many varieties of sharks, and among the many photographs and illustrations are wonderful paintings by Ellis himself. We love Richard Ellis here at Needcoffee. We talked about fabulous book, The Search for the Giant Squid, back in 2003. His works are definitely worth checking out, so why not snag The Book of Sharks to start with?

Shortfin mako shark, Condor Bank, Azores in 2011 – Image by Patrick Doll CC license

Our better-known predator of the day is the Mako Shark. Streamlined and agile, it is the most hydrodynamic and therefore, the fastest of the shark family. The shortfin mako has been clocked at 31 mph, and it is theorized that they may be able to make short bursts of 45 mph. But there are weirder things about the mako than just its speed:

  • Makos like to jump out of the water from time to time (sadly, this is often viewed when they’re on a fishing line), and perhaps because of their streamlined body shape and speed, can do this very acrobatically, up to 15 or 20 feet in the air above the surface.
  • Mako sharks are one of four species of sharks that can control their body temperatures to some extent, making them, in essence, warm-blooded sharks.
  • This is really creepy. Before they are born, mako shark pups eat their siblings in utero to nourish themselves. This rather disturbing example of survival of the fittest is called intrauterine cannibalism.
Image by Green Fire Productions under CC license

Less dangerous than the mako to everyone but plankton, the Basking Shark is an odd-looking gentle giant.

  • Like whale sharks, they are filter feeders, and have the odd behavior of swimming with their mouths open and gills exposed to feed.
  • In the winter, basking sharks “hibernate” by hanging out in deep water.
  • Basking sharks, oddly enough, are often mistaken for much rarer (and fictitious) creatures. Many reports of sea serpents have been attributed to basking sharks, due to their habit of “basking” in the sun near the surface and showing bits of fin and back that might appear to be a serpent-like creature. A famous supposed-plesiosaur carcass pulled up by a Japanese fishing boat in 1977 was a cryptozoologist’s dream until it was proven that it was a decomposed basking shark.
Image by Elias Levy under CC license

A member of the Carpet Shark family, Wobbegong Sharks are similar to the angel shark in that they are camouflaged bottom-feeders.

  • The name “Wobbegong” is Aboriginal Australian (pronounced “wob-ee-gong”).
  • Wobbegong sharks have branch-like fleshy bits around their mouths that look like yummy seaweed to smaller fish. The sharks will often rest on the bottom, hiding, until an unsuspecting fish gets close enough to nibble on the “seaweed” and becomes lunch for the shark instead.
  • Octopi are one of their favorite foods.
  • They sometimes use their pectoral fins (the ones on either side of their bodies) to “walk” over rocks near the bottom. A cousin of the wobbegong shark, the Epaulette Shark, has such agility with its flipper coordination that biologists think their movement and behavior during their “walks” may be a clue to how the first amphibians made the transition from water to land.
  • Strangely enough, Wobbegong sharks are part of the same taxonomic order (Orectolobiformes) as Whale Sharks

As strange as the Wobbegong shark may look, I think our Odd-Looking-Shark-of-the-Day winner might just be the Saw Shark.

Saw shark
Photo by David Clode on Unsplash

Baby saw sharks are born with the teeth on their snout (called “rostral teeth”) folded back, perhaps so the mother will not be injured during delivery. The rostral teeth grow back when they break or fall out. Like all sharks, saw sharks have a special sensory organ called the ampullae of Lorenzini, which help them to detect electrical signals. Like hammerhead sharks, they can detect animals hiding under the sand using their “sixth sense.” They use their “saw” to stir the sand up, flushing out their prey, and then slash at them to stun or kill them, making them easier to devour.

I wanted to find a video of a saw shark feeding. Instead, I found this fabulous one from Japan in which the saw shark… just sits there. The editor was apparently disappointed by the lack of enthusiasm on the part of the shark, so he put in some kickin’ music and a few cuts to different angles of the shark hanging out at the bottom. On a more educational note, you can see the long nasal barbels (no, not barbells) that also help the saw shark detect prey.

Blue shark

The Blue Shark is a very distinctive indigo color, with a more traditional sharky shape and long pectoral fins.

  • They are fished heavily, sometimes from sport fishing, but more from commercial fishing, often accidentally by fisherman trying to catch different prey.
  • The sex of a blue shark can be determined by the presence or absence of bite marks. Apparently, the males can’t keep their teeth to themselves when mating. But due to the beauty of evolutionary traits, perhaps, the skin of the female blue shark is twice as thick as the male’s.
  • Uber-marine biologist Valerie Taylor, along with her husband Ron, originally tested the now-common chain mail shark suits by letting blue sharks (and other smaller sharks) bite their arms. The sharks bit, but did not break the tiny metal links. More on Ron & Valerie Taylor here.
  • Blue sharks are countershaded; that is, they have lighter coloring on their bellies so they’re less visible from below, and darker coloring on top, so they’re less visible from above. Sneaky, but not quite as sneaky as the cookie cutter shark.

Thanks for sticking around for Day Four. We’ll finish up our species exploration tomorrow! If you’ve missed some over the past few days, feel free to catch up!

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