Shark Week: The Unknowns

It’s that time of year… Shark Week! Great Whites, hammerheads, and bull sharks, among many of their toothy counterparts, are well known and highly featured in the media and shows like shark week. But let’s take a peek at some of the hidden sharks, the least well-known, overshadowed, and newly discovered sharks to provide a little more depth to our ocean of shark-y knowledge…

Let’s start with a shark often called a “living fossil”…. the frilled shark.

frilledshark

The frilled shark is one of two of the oldest shark families, with it’s ancestors living 95 – 150 million years ago (during the Cretaceous and possibly Jurassic period), hence being commonly called ‘living fossils’. This shark has a few differences from what comes to mind when you think “shark” : it has a long eel-like body with smaller fins set close to the tail, a jaw that can unhinge or articulate (like a snake) allowing the shark to swallow prey half its size, and widely spaced needle or hook-like teeth. Frilled-SharkThe frilled shark is most commonly found in Japan (Suruga Bay) but lives in scattered pockets around the world(Australia, Norway, France and Morocco, Brazil, New England, and even Hawaii) and likes hanging out in deep water near the bottom. Most often, frilled sharks will be cruising along the continental shelf and slope around 200 – 3,000 feet deep, but they have been found as deep as 5,000 feet and as shallow as the surface (usually the animals at the surface are sick, injured, or dying). Rare surface sightings of a larger frilled shark ancestor may be the reality behind the myth of sea serpents. Discovery’s Alien Sharks featured these creatures of the deep in a pretty cool video here.

On to the basking shark: second-largest fish in the sea (the #1 spot goes to the widely-known whale shark)

Basking_Shark

Like the whale shark and the megamouth shark, this shark is a filter-feeder. With [mouths] wide open, under the sunlight… these sharks cruise at the surface feeding on zooplankton and other teeny-tiny organisms (heard of krill, right?), ‘basking’ in the sunlight while enjoying their meal. The largest recorded length for these guys was over 40ft long and 21 tons (that’s 300+ of me!); the average basking shark will reach 20-30 feet (6-8 meters) long and only weigh 7,000 lbs. Basking sharks are slow swimmers and inhabit warmer waters through the Atlantic and Pacific oceans – from Canada to Florida, Northern Europe to the Mediterranean, the southern tips of South America and Africa, Japan, Australia, and the west coast of the U.S. Basking-shark-09Sometimes, these sharks have been confused with great white’s because of their size, coloring, and shape (when their mouths are closed). Fortunately, they are gentle giants who are very patient with divers and boats nearby. Also social animals, basking sharks often travel in pairs and congregate in large schools of 100+ individuals!

And last, but not least…well maybe…the newly discovered (and probably the cutest) pocket shark

Pocket-Shark-Held-With-Gloves

Only two pocket sharks have ever been found: the first over 30 years ago in deep water (330 meters, 1,000 ft deep) off the coast of Chile and the second while sampling for sperm whale prey in the Gulf of Mexico. These two sharks were both small, a 15 inch adult female and a young male only 5 1/2 inches (young male still had an unhealed umbilical cord scar).

1430023839256713I’m sure this joke has already been made, but here we go again! – while they are small enough to fit in your pocket (hah!), that is not where they got their name. Scientists noticed a pocket behind the shark’s pectoral fins (the two near what would be their chests – or pecs – aka pec-toral). The reason or use for this pocket is unknown, but researchers think it may be used to hold a bioluminescent fluid. This educated guess would fit with what is known from other species of the pocket shark’s habitat – the deep ocean (we talked a little bit about it here). These clues and the structure of the jaws hint that the pocket shark may feed and live similarly to the cookie-cutter shark – which takes circular bites out of other animals for food. That possible mode of feeding takes away some of the ‘cute’ factor for pocket sharks, but they’re discovery just goes to show you that we still have a lot to learn from our planet!

And for those Shark Week fanatics, this is Discovery’s Shark Week schedule.

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