Shark Week 2018

With their huge, sharp teeth and menacing demeanor, it’s no wonder this ocean predator has long struck fear into the hearts of many. Thanks to films like Jaws and Sharknado, sharks have gained a reputation for killing and eating humans, yet there are under 100 unprovoked shark attacks each year, and even fewer fatalities—you’re more likely to be killed by lightning or a bee sting than you are by a shark!

As Discovery Channel’s Shark Week celebrates its 30th year, we have selected some facts for you to enjoy between shows—one for each day of the week.

• You thought you’d never go in the water again…
  Cage diving with sharks may seem like an enticing opportunity to get up close and personal with these fearsome creatures without the risk of being eaten, but it’s a damaging experience for sharks, which have a limited amount of energy. When cage diving occurs, shark activity in the area increases as the sharks detect the presence of potential prey (as well as shark “attractants” used by tour operators). However, they receive no payoff for exerting this hunting energy, consequently decreasing the species’ fitness.
• When the hunt is on, the heat is on
  When hunting, great white sharks have to be able to propel themselves forward in short bursts while also swimming long distances in very low temperatures. To do this, the shark has to increase its internal temperature so the muscles can perform by using its thermoregulatory system.

• Could tuna be the next Jaws?
  You may not find the fish you put on your sandwich frightening, but maybe now you might: tuna and sharks share the same “super predator” genes! While tuna don’t have the genes that create the shark’s huge teeth, the two creatures do share certain predatory genetic traits, such as their fast metabolism and ability to swim quickly, enabling them to catch prey in inhospitable waters.

• “Sisters before misters” applies to sharks too
  Female solidarity is strong in the shark world. Studies show that closely bonded groups of female sharks are more resilient to male disturbance: when confronted by a male seeking a mate, groups of ladies are less likely to pair off with the male. In contrast, solitary females cycle through male partners more frequently.
• Barcode scanning isn’t just for groceries
  Thanks to a demand for shark fin soup in the Asian market, shark harvesting is rife despite the bans on capturing endangered species. At local fish markets, many sellers get away with illegally trading sharks by removing any distinctive features, such as fins and heads. However, DNA barcode scanning can be used to better monitor this, through the extraction of short strands of DNA that can be quickly analyzed. Such advancements will hopefully lead to a reduction in illegal trading.

• Stress is felt in a fish out of water
  Sharks can be accidentally caught in fishing nets alongside a fisherman’s regular harvest, but are later released back into the ocean. This catch and release can have a detrimental impact on sharks’ wellbeing: some sharks, including hammerheads, experience physiological changes and reflex impairment following capture, which suggests a higher vulnerability to fishing. Other sharks however, including nurse sharks, experience very little or no physiological changes and appear better equipped to being caught and released.
• Coral reefs provide respite
  As ocean acidification rises, sharks (along with other sea life) will have to adapt. Ocean acidification is occurring due to the increased level of carbon dioxide in the atmosphere, some of which is absorbed by the ocean and increasing its acidity. The epaulette shark is able to cope with this: the shark is not only capable of withstanding low oxygen levels, but also short periods of elevated carbon dioxide levels, by inhabiting shallow waters and hiding in coral reefs.

• Shark size doesn’t matter
  Different species of shark are highly varied in their biology and behavior, but it appears that no matter the size of the shark, their anatomy is geometrically similar. For example, different species of shark have the same-sized fins proportional to their overall body size. In fact, the most important variance between different shark species is not their bodily proportions but their overall body length, as this is often linked to their diet.

Featured image credit: Great White Shark by Elias Levy. CC BY 2.0 via Flickr.