There is an extremely rare fish that may hold some key missing evolutionary information.
The cave angel fish (Cryptotora Thamicola) is the only fish in its genus. This uncommonly found fish does something equally as uncommon.
It climbs waterfalls.
This waterfall climbing cave fish comes in at about an inch long. It’s not a very large fish and it’s even less common in nature.
There are about 2,000 reported fully grown cave angel fish. What makes these fish even more rare is that they are only found in 8 caves in the world. All 8 are in and around Thailand.
To make studying these crucial pieces of understanding evolution even more difficult, these 8 caves are all highly protected by the Thai government. In fact, it’s almost impossible to enter these caves.
The american scientists who were studying this fish weren’t allowed to dissect and experiment on them like with traditional fish. They actually needed to join forces with a local scientist to get permission to even enter the cave.
The rarity and exclusivity of its ecosystem has made studying this fish difficult. The persistence of certain scientists has delivered us some new intel which can help shine some much needed light on the missing links of evolution.
The Evolutionary Importance Of The Cave Angel Fish
First and foremost, you need to understand what’s so special about the way this cave fish walks.
Most cave fish look like this:
Image courtesy of Pixabay
Notice the fins. They don’t “slither” the way the angel cave fish walks. Traditional cave fishes (like the image above), use their fins and “upper body” muscles to push and drag themselves. This looks more like a slug dragging itself along than walking.
In the video you see the way that the cave angel fish walks. It actually uses stepping movements.
Further analysis showed that the fish walks very similar to how a lizard does, despite being more closely related to a goldfish.
This is an example of convergent evolution. These fish aren’t closely related to reptiles, yet they seem to be able to walk just like them.
Further analysis shows that these small crawling fish have large pelvises that are almost attached to their spine. This allows them to push through their limbs in a step like motion. They developed this way due to their unique environment. They evolved from simple fish (like the photo above) into fish that can use reptilian like steps.
Watch the following video to get some better insight into the possible evolutionary implications:
There has always been a few missing links in evolution. Scientists have accepted that life started in the ocean, but one of the missing links is how these fish evolved into tetrapods (four legged walking animals).
This angel cave fish has a body structure that remarkably resembles that of the tetrapod. While it is a stretch to say that this fish is a direct copy of what the ancestor that linked fish to reptiles millions of years ago looks like, you can say that it helps you understand what that ancestor did likely look like.
How did we go from non-legged animals to legged animals? What did the transition from “fin” to “limb” look like?
What we do know is that this transition happened some 40 million years ago.
What we know now, is that there is a clear route for a fish to develop a tetrapod type body structure and stepping style.
As you watch the video of the fish climbing the waterfall, you see a clear similarity to how four legged animals walk.
So how can this discovery be practically used in modern science?
Well for starters, if anyone still doubts some of the big missing chains in evolution, you can use this discovery to help them see the light.
A hyper specific ecosystem can lead to a fish that can climb walls.
We can see how small bacteria turned into more complex species. We can see how smaller fish turned into larger and smarter fish. We can now see how fish left the water and developed legs. We have a very good understanding of tetrapods, and know that eventually these animals evolved into standing upright. We know that we shared a common ancestor with chimpanzees along this development.
There are only a few more holes left to fill. The discovery of the angel cave fish is a great relief for those worried about these potential missing links.
The more discoveries like this are made, the better understanding we will have on the entirety of evolution.