What Sharks Do We See?

Photo by nautiluslive.org

Did you know there are 40 species of sharks found around the Hawaiian islands?

You have the chance to see so many different species of sharks when you come on a dive with us! This could include Galapagos, Sandbar, Tiger, Oceanic Whitetip, Oceanic Blacktip, Blue, Silky, Whale, or even a Great White! We haven’t seen a Great White since 2005, so we’re always on the lookout for another one. Whale sharks are more commonly seen on the west side of the island due to the very deep water. The most commonly seen sharks we get are Galapagos and Sandbar. Galapagos sharks average 6-12 feet in length and have distinct countershading. This means they are dark on the top half of their body (dorsal side) and lighter on the bottom half (ventral side). Sandbars average 4-6 feet in length and are a tannish color with white tips on their pectoral fins. We also get Tiger sharks fairly often, even when it isn’t Tiger shark season! Tiger sharks average 10-14 feet and have dark stripes running down the sides of their bodies. Recently, we’ve had an Oceanic Blacktip hanging around during our dives as well! Blacktips average around 6-8 feet and are bronze in color.

If you want the chance to see different species of sharks in their natural habitat, book a dive with us at oneoceandiving.com.

Meet Kevin, the barracuda we see often as any shark

Photo by Tyler Flott @beach_ty

Hawai‘i hosts two species of barracuda: the great barracuda or kaku (Sphyraena barracuda) and Heller’s barracuda or kawelea (Sphyraena helleri). Kaku can grow to about six feet long and 100 pounds. Kawelea are active at night, forming schools near the reef during the day. This smaller species grows to about two feet long.

According to a 1997 entry of the Honolulu Star-Advertiser’s Ocean Watch column by Susan Scott, Barracuda eat both large and small fish, striking with lightning bursts of speed. Unlike some fish predators, barracuda can’t expand their mouths to swallow large fish whole. To eat big prey, barracuda slash them to pieces with remarkably sharp teeth. A large barracuda can cut a mature parrotfish in two pieces with a single bite.

“The one time I did see a barracuda catch a fish, it happened with such swiftness that I couldn’t make out any of the details,” Scott writes. “A little fish was there; the barracuda jerked; the little fish was gone.” 

A kaku has frequented the One Ocean dive site for over a decade so, like many sharks we have come to know, he has been given a name—fondly referred to by guests and captains as Kevin. Over the years, Kevin has become a fan favorite, rivaling even some of our famous sharks. Each time Kevin is mentioned on social media, guests’ comments reminisce on times they saw the barracuda among a school of Galapagos or sandbar sharks. 

According to the Star-Advertiser, kaku are active during the day and camouflage to catch fish. Juvenile kaku typically shelter in reefs and harbors. While adults are sometimes spotted in these types of places as well, they head offshore to hunt in the open ocean when they grow too big to fit. 

Barracuda, like sharks, can appear menacing to the inexperienced. Should the average diver be afraid of barracuda? 

“Like sharks, the answer is usually no,” Scott writes. “Of the twenty-two barracuda species found throughout the world, the great barracuda is the only one known to attack humans. The risk of being bitten by this fish, however, appears extremely low.”

Between 1873 and 1963, there have been only nineteen confirmed cases of barracuda attacks globally, the column reports. Four of these took place in Hawai‘i.

Also like sharks, most theorize that barracuda attacks only occur by mistake. Barracuda may view the flash of jewelry or camera equipment as a silvery fish. In most cases, barracuda keep their distance from people. 

Kevin is no exception. While he is sometimes affectionately called a grump from his demeanor and lack of playfulness, he tends to linger on his own among the sharks and people. 

Photo by Tyler Flott @beach_ty

Kevin was named after One Ocean’s Captain Kevin Chadick some fifteen years ago, so unfortunately the story behind it has been lost to lore. While this timeframe makes up the whole of a barracuda’s lifespan, it’s possible “Kevin” is multi-generational, or (at the risk of spoiling a Santa Claus-esque myth) perhaps even a moniker of any kaku who hangs out in our waters. 

Photo by Tyler Flott @beach_ty

Whatever the case, if you happen to see a lone barracuda among the flurry of sharks at our dive site, make sure and give a warm aloha.  

All About Shark Senses

Sharks have developed their senses over millions of years to become the apex predators that they are today.

Their vision is actually about the same as humans! However, they see in monochromatic vision, which means they see colors on a greyscale. Any colors that are high in contrast such as yellow, orange, and white stick out to them.

This is the reason that we dive with dark colored gear (grey, black, blue, red, green). For example, if you wear an all black wetsuit and a white glove, a shark would see that as two separate entities and be more likely to come in close to check out the glove hand. By wearing dark colored gear, we’re lessening the likelihood that a shark would feel the need to get close to check something out.

If you wear a bright color on your body, the shark can still tell that you are a larger organism, and would be less likely to approach. We try to eliminate bright colors on extremities, but on the body, different colors are not as important.

GoPro poles are another item we often have to swap out for guests before dives. Many people have the bright “yum yum yellow” GoPro pole, so we swap it out with a black one. Since the shark can detect the GoPro using its ampullae of Lorenzini and can see the bright pole, it would be likely to come in and take a closer look.

The Ampullae of Lorenzini are jelly filled pores on the top of the sharks head. These pores detect electrical impulses such as heartbeats, boat engines, muscle contractions, and electronic devices, such as the GoPro mentioned above. For this reason, we ask guests to take off smart watches before they enter the water. This is why we ask for GoPros to be on poles.

Sharks also have a great sense of smell. Many people think sharks are attracted to the smell of humans and human blood, but that’s not true! Sharks don’t associate the smell of humans or our blood with food, so you can swim while bleeding without having to worry!

Sharks also have great hearing. They can hear boats coming from a mile away and birds splashing on the surface from 300 yards away! This is why it’s so important to keep splashing to a minimum when you are swimming in the ocean. Splashing mimics injured prey which could attract a curious shark.

If you want to learn more about sharks’ senses, check out Ocean Ramsey’s book, What You Should Know About Sharks.