Living fossils in the deep sea, hidden miracles of golden geometry?

Nautilus is a general term for marine molluscs in the class Cephalopoda and family Nautilidae. There are 2 genera and 6 species in total, and their morphological differences are mainly reflected in the size, shape and decorative patterns of the shell. Although the nautilus is somewhat different from modern octopuses and squids in classification, they both belong to the class Cephalopoda and share well-developed head and neck muscles, complex eyes and flexible tentacles. It is also the only species in the class Cephalopoda that has a true shell. The method of movement it excels at is jet propulsion! Like its close relatives, squids and octopuses, it will spray water to get backward propulsion when in danger and quickly escape!

Nautilus is basically a benthic animal. It usually crawls slowly on the bottom of the water 100 meters deep with its wrists. It can also use the secretions from its wrists to attach to rocks or coral reefs. They use the gas-filled chambers in their shells to adjust their buoyancy and rise and fall freely in the water. Submarines are made by humans based on the principle of vertical rise and fall of nautilus in seawater. The world's first submarine is called "Nautilus". "Nautilus" weighs 2,800 tons and cost a total of 55 million US dollars. The entire hull is 90 meters long, with an average speed of 20 knots and a maximum speed of 25 knots. It can sail continuously for 50 days at the maximum speed and a total distance of 30,000 kilometers without any fuel.

The golden ratio is a magical constant, and the shape and size of the Nautilus shell show the mathematical golden ratio (about 1:1.618), which is considered an aesthetically ideal ratio in nature. This ratio not only gives the Nautilus shell an elegant appearance, but may also be related to its survival strategy. The appearance of the golden ratio in the design of the Nautilus shell is not only the result of natural selection, but also provides inspiration for modern design. For example, architects and engineers draw on the shell design concept of the Nautilus to optimize building structures.

The shell of the nautilus is not only a key structure for its survival, but also an important piece of evidence for studying paleoenvironment and paleobiogeographic distribution. Through a detailed analysis of the nautilus fossils, the study shows that there are 26 growth lines on the shell of the Oligocene of the Cenozoic Era; 22 in the Cretaceous of the Mesozoic Era; 18 in the Jurassic of the Mesozoic Era; 15 in the Carboniferous of the Paleozoic Era; and 9 in the Ordovician of the Paleozoic Era. It can be inferred that the moon is moving away from us and it will become darker and darker.

Nautilus was almost universal in the Paleozoic Era, but has basically become extinct, with only six species still existing in the deep sea of ​​the South Pacific. Today, all species of Nautilus (including living, dead and fossil) are listed in the United Nations Convention on International Trade in Endangered Species of Wild Fauna and Flora; all species of Nautilus are listed as Least Concern (LC) to Endangered (EN) by the World Conservation Union; all species of Nautilus are listed as first-class protected animals in my country.

References

[1] Lu Guanya, Xu Pingping, Yang Yi, et al. Key points for morphological identification of nautiloids and plano-rotating ammonites[J]. China Port Science and Technology.

[2] Wang Chunxiao. The magic of the “golden ratio”[J]. Mathematics.

[3] Ma Ruiqi. Nautilus: I also understand the "Fibonacci sequence" [J]. Mysterious Nature.

[4]https://baike.baidu.com/item/%E9%B9%A6%E9%B9%89%E8%9E%BA/207068?fr=ge_ala