Shulou(Shulou.com)11/24 Report--

(photo Source: wiki) Writing | A Xian

Revision | Ziv

Can you draw fish?

If you find a random child, you will probably draw the fish on the left with a pointed mouth and a slender body. it is rare to see people paint the fish as a square box. However, this kind of "alien" fish does exist in nature!

Editor: does it look good? I drew it! (the ostentatious fish on the right resembles a yellow box, called Ostracion cubicus, commonly known as papaya or yellow box fish. They like to inhabit coral reefs in the Pacific, Indian Ocean and eastern South Atlantic, pouting and pouting, feeding mainly on small prey (small worms, crustaceans, molluscs and small fish) and organic debris on reefs.

The body color of the young fish is bright golden yellow, the body is covered with black round black spots, and the whole fish is like a small round ball with yellow black spots. As the fish grows, the black spots will become smaller and smaller, and the fish will have a blue-gray appearance. Because the yellow box fish likes to live alone and timid, the bright yellow and black spots become a warning against potential predators.

When yellow box fish are attacked or threatened, the skin also releases a neurotoxin (Ostracitoxin) unique to the family Carpinidae. Many people try to raise it but fail because if they are in relatively closed waters, such as aquariums, the toxins released may cause "mass extinction" of other fish in the tank.

Wiki most fish, from bass to sharks, have a soft, streamlined body that adapts to aquatic life, allowing them to swim in the water. But the yellow box fish has a hard skeleton in the shape of a box, which is so different from the fish we usually know that it makes one wonder if there is something wrong with evolution. After all, it is too slow and difficult to swim in the water with this kind of fish.

However, surprisingly, although it looks silly, the yellow box fish is so agile that it is almost one of the most agile fish in the coral reef area. How do they swim?

Source reference [3] in 2002, a group of researchers used 3D printed models of box cuttlefish to study how water flows around their bodies. They found that when the current hits the yellow box fish laterally, small swirls form near their bony shell, stabilizing the fish's movement. This ingenious survival technique is important to reduce the disturbance of the current when the yellow box fish swim and to maintain stability in turbulent waters, and people seem to have finally found a reason why the yellow box fish have not been evolutionarily eliminated.

If you look closely, you can see that it clings to its tail. YouTube, however, the researchers seem to have overlooked one detail: if the vortex around the yellow box fish's carapace can provide it with directional stability, and any change in course is offset by the vortex, then they will become too stable to turn quickly to avoid predators. And, according to people's observation of the yellow box fish, it is a very flexible "yellow box". When it is in danger, it will quickly turn around and escape into the reef.

Yellow box fish: I am really a very flexible half of the moon! I don't believe it. Look! | YouTubeS. The 2015 study by Van Wassenbergh et al opposed the previous vortex theory, arguing that the effects of these eddies were actually offset by the torque generated in front of the square skeleton of the yellow box fish, which could not swim in a stable posture. On the contrary, they were very easy to "roll over." The reason why the yellow box fish is very flexible is to use the dorsal fin, pectoral fin and anal fin to roll quickly (similar to the helicopter propeller) to help the body stay upright in the flowing water. When they need to turn quickly, simply bend the caudal fin to the side, and their bodies "turn over" to help the yellow box fish turn in a very small space.

In other words, the agility of yellow box fish is formed by a combination of aerodynamically unstable bodies and the movement of fins, coupled with the fact that they do not need to swim long distances and carry venom and "armor". So choosing agility instead of speed is the choice of long-term evolution.

In 2006, Mercedes-Benz launched its bionic concept car, inspired by the yellow box fish. | when Wiki sees this, someone may want to ask, how do normal fish swim? If you look at the way fish move, you will find that they all move in the same way, through the regular left and right swings of the tail and the fish's body and the coordination of the fins.

The pectoral and ventral fins can maintain the balance of the fish in the water, unlike other fins, the pectoral fins are not vertical but horizontal, so the pectoral fins swing up and down during movement to help the fish control their ups and downs. The dorsal and anal fins keep the fish upright in the water, like the keel at the bottom of a sailboat (a longitudinal member connecting the bow post to the stern post in the middle of the hull).

Source reference [4] the caudal fin can not only provide additional help for the swimming of the fish, but also help the fish change the swimming direction. The caudal fin swings to the left, the fish moves to the left, the caudal fin swings to the right, and the fish moves to the right.

However, due to differences in living environment and habits, the function and shape of fins are also changing during the long-term evolution. For example, tuna and swordfish have fork-shaped or crescent-shaped tails (figures 1 and 2). Suitable for long-distance, endurance swimming; round tail is suitable for slow swimming.

Source reference [4] when I saw the yellow box fish, I thought of a lyric: "you say toot, beep."

(image source YouTube) Resources:

[1] https://australian.museum/learn/animals/fishes/yellow-boxfish-ostracion-cubicus/

[2] https://royalsocietypublishing.org/doi/full/10.1098/rsif.2014.1146

[3] https://www.nature.com/articles/517274a

[4] https://www.fishandboat.com/LearningCenter/PennsylvaniaLeagueofAnglingYouthPLAY/PLAY2002/Documents/fishswim.pdf

[5] https://en.wikipedia.org/wiki/Yellow_boxfish

This article is from the official Wechat account: bring Science Home (ID:steamforkids), author: everything Magazine

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.