For a long time, researchers believed that tuna were the fastest fish in the sea. Now, scientists conducting research around Australia’s Great Barrier Reef have made a startling discovery. As it turns out, the world’s fastest fish is not necessarily the tuna; Blue Line Wrasse can travel at the same speed, and they use less energy to get to their destinations. Here, we’ll take a look at a fascinating little fish that has researchers spellbound.
Blue Line Wrasse Basics
The wrasse family contains more than 600 distinct species, all of which are efficient carnivores that feed on small invertebrates of various types. Wrasses inhabit the Indian, Atlantic, and Pacific Oceans, and are usually found along rocky shores and in coral reef environments. If you’ve been diving in tropical waters, the odds are good that you have encountered wrasse, including blue line wrasse.
While these animals get their name from a Welsh word, “gwrach” that means “hag” or “old woman,” they are actually very beautiful, and they’re often some of the most colorful fish you’ll encounter when diving.
Blue Line Wrasses are sometimes referred to as rainbowfish – they’re just that colorful. You’ll normally encounter them swimming singly in shallow water along outer reef slopes and near drop-offs where coral is abundant, and they can often be found taking shelter in channels and under overhangs. They typically grow to just about 14 centimeters, and they are strictly diurnal.
It wasn’t their beauty that caused the fish to attract scientists’ attention, though. It was the unique way they flap their fins in an energy-efficient figure eight pattern that caused researchers from the Australian National University and the ARC Centre of Excellence for Coral reef studies to give the fish a closer look.
Upon comparison with other fish, it was discovered that while fish like tuna move their tails and bodies in an undulating motion to propel themselves through the water, and while some fish use their pectoral fins in order to produce thrust in a paddling motion that moves them forward only with every other stroke, the Blue Line wrasse produces thrust the entire time it paddles, and it uses very little energy to do so.
Says Dr. Chris Fulton, who participated in the study, “This figure-eight fin sweep allows the Blue Line wrasse to create a lift force as the water flows over the fins, in a very similar way to how birds fly through the air. This mans the fish are literally flying underwater.” The study showed that these fish are the fastest swimmers for their size, and not only does that give the fish an advantage in the environment they live in, it also gave scientists an idea for a new underwater robot.
Currently, AUVs (Autonomous Underwater Vehicles) use jets or propellers located at their rears. “By replacing these with fins at the front to mimic how Blue Line wrasses flap their fins, we could propel robots with less power, saving on batteries and increasing their range.” Dr. Fulton said.
Considering that AUVs and ROVs are being used for studying and tracking marine animals like sharks, and even for cleaning up underwater environments, it seems as though the Blue Line wrasse has led researchers to a solution that could help improve the very reefs where these amazing little fish live. Next time you see an interesting reef fish, try thinking outside the box – you might come up with a brilliant idea like Dr. Fulton and his team did.