Although at first glance the ‘O’opu fish might not attract the attention of observers, since its appearance does not seem to have any extravagant features, when it sees it move everything suddenly changes. This fish has a hidden treasure in its behavior and it is the only one of its kind that can climb stones.
Endemic to Hawaii, as soon as they emerge from their shell the ‘O’opu are already facing the storms of nature. Within just a few seconds of being born, the fish have to swim against the current and face the enormous force of the fluidity of the rivers in order to reach the sea where they live a slightly calmer life.
However, for the survival of their species, the ‘O’opu have to go through an even more incredible feat; that of climbing large cliffs with unexpected waterfalls. When they reach reproductive age, they leave the sea to enter the streams of Hamakua, Hawaii, which is the region that has the largest population of this species of fish in the world.
They do this to find a safe place to lay their eggs and thus guarantee their own survival. At the top of the streams, their eggs are safer from predators and have a greater chance of hatching, however, this makes them face a much greater difficulty than swimming against the current, that of climbing large waterfalls.
Once you enter the streams, swimming against the current will not be the most difficult adventure. Stone climbing is one of their great skills, little by little they adhere to the slippery surfaces of the river stones to undertake their feat. Surprisingly, they don’t do it just once in their lives, but rather go uphill a few times a year.
Three times Mount Everest
‘O’opu fish have patterns on their skin that help them camouflage themselves among the river stones on their climbing adventure. They have colors ranging from brown to gray and even gold. In addition, they are small compared to others in their same biological group, as they do not exceed 18 centimeters.
In total, there are 5 variants of ‘O’opu fish known, but all of them have the same behavioral characteristic: jumping out of the water to adhere with their bodies to the rocks in the waterfalls. Once there, they begin to climb propelled by their mouth and abdomen, in addition to using their fins as reinforcements to continue uphill.
According to biologists, the effort that these small fish make when climbing the waterfalls is enormous. To put it in context, its equivalent for humans would be to climb Mount Everest three times, a very grueling adventure if we put it this way. However, for the ‘O’opu, defying gravity is part of their evolution and that is why they are so special.
This story was originally published in Spanish in Ecoosfera
