The Nautilus is the only species of living cephalopods whose coat is located inside its shell, and they have lived on Earth for nearly 500 million years. However, the Nautilus family, which once flourished in the world's oceans, is now limited to a small area of the Indo-Western Pacific Ocean, and there are only 2 genera and 5 species, the most widely distributed and most common of which is the pearl nautilus pompilius.
Pearl Nautilus | Hans Hillewaert / Wikipedia
The surface of the shell of the pearl nautilus is very smooth and varied, with irregular brown to reddish-brown stripes extending from the umbilicus to the abdomen, but these patterns appear only in the upper part of the shell.
The opening of the live nautilus is upward, and the dark pattern of the upper half of the shell and the white shell of the lower half help to reduce the chance of detection by predators on or under the surface of the water. The umbilicus of the pearl nautilus is small and closed and healing, and the internal circling is invisible, usually with thickened calcareous indurated tissue.
The pattern of the pearl nautilus | Profberger / Wikipedia
< h1 class="pgc-h-arrow-right" > different nautilus </h1>
It is widely distributed in the Indo-Northwest Pacific region, including the Andaman Islands, Ambon Island (Indonesia), the Philippines, New Guinea to Fiji and the northeast and northwest of Australia. It inhabits water depths ranging from 0 to 750 meters above water surface. Like many cephalopods , the pearl nautilus has a pronounced vertical migratory habit.
The vertical movement of cephalopods is mainly divided into two types, one is the vertical movement between day and night, that is, resting in the deep water area during the day, avoiding large predators, and migrating to the surface waters at night to ask for bait; the other is the glass squid just introduced in yesterday's species calendar, which gradually deepens the depth of life water during its ontology as the carcass length increases. The vertical migratory habit of the pearl nautilus belongs to the first type.
Remember yesterday's glass squid | H.J.T. Hoving，et al. / Deep Sea Research Part I: Oceanographic Research Papers（2017）
The Nautilus is the only group of cephalopods that employs a multi-round spawning strategy. The simple understanding is that after each round of egg laying, the female glands will re-develop and then start a new round of spawning activity. Female nautilus in the spawning period still forages as usual, and after spawning, the female nautilus does not die like most cephalopods and continues to grow normally.
Different Nautilus | Wikipedia
In addition, the eggs of the Nautilus are not as many eggs together as octopus and squid. The pearl nautilus is a single egg produced, and it lays eggs in places such as underwater coral crevices. The incubation time of the eggs depends on the ambient temperature and it can take up to 15 months to hatch. The larvae do not hatch from the eggs and begin to live freely until the snail shell has fully grown.
In 2017, the Monterey Bay Aquarium in the United States released a video of a small nautilus that had just broken out of its shell, which may be the world's first video of the nautilus hatching.
The little nautilus that had just broken its shell | Monterey Bay Aquarium / YouTube
<h1 class="pgc-h-arrow-right" > a pattern specimen with a twist and turn </h1>
Although the Nautilus appeared in naturalist atlases as early as the 15th and 16th centuries, it was not until 1758 that Carl Linnaeus officially named the pearl nautilus in the 10th edition of Systema Naturae (Natural Systems). Linnaeus published a new genus in the magazine, Nautilus, which was named after the ancient Greek nautílos, meaning sailor, and named 17 new species in one go. However, the vast majority of these 17 species, with the exception of the pearl nautilus, are far from the nautilus, and at least more than half of the species are foraminifera.
Confused foraminifera | Alain COUETTE / Wikipedia
According to naming conventions, each new species should be published with a model specimen of that species designated by the namer. However, when Linnaeus published the Pearl Nautilus in 1758, he did not mention any physical specimens except briefly quoting 10 illustrations that had appeared in other publications before, nor did he specify which specimen was the holotype of the pearl nautilus.
However, this is said to be a personal habit of Linnaeus, who usually does not mention in The Natural System whether there are physical specimens of species he has seen or collected.
The title page of the tenth edition of natural systems | Carl Linnaeus《Systema Naturae》
In 1767, Linnaeus assigned a lectotype to his previously published pearl nautilus in the 12th edition of Systema Naturae, a plate drawn in 1705 by the botanist Georg Eberhard Rumphius. It sounds incredible, but it's not uncommon to use illustrations instead of describing published species, and of course the principle is that the illustration must be drawn with reference to a physical specimen.
However, it was later confirmed that the three Nautilus illustrations in the Langferens plate were from 3 different specimens, which apparently did not comply with the requirement that the mold selection should come from the only specimen. Even so, in some subsequent papers, everyone tacitly agreed to linnaeus's 1767 painting, the one he painted by Lang Fuens, as a model specimen of the pearl Nautilus.
The Nautilus |, painted by Lang Foyens in 1705 Georg Eberhard Rumphius
< h1 class="pgc-h-arrow-right" > pattern specimen, it's decided that it was you </h1>
In May 2015, Dr. Svetlana V Nikolaeva examined a large number of early documents and specimens of documents that could be found, comparing the 10 illustrations cited by Linnaeus, and found that none of the early illustrations corresponded to existing specimens, and even some of the pictures were completely early art illustrations or reproductions.
According to the naming convention, a suitable specimen should be found from the series of co-mode specimens in which Linnaeus named the pearl nautilus at that time and designated it as the mold of the pearl nautilus. Nikolaeva found a specimen of the pearl nautilus at the Linnaean Society in the United Kingdom, but after literature search, Linnaeus never seems to mention this specimen, and none of the 4 nautilus specimens in the collection of the Uppsala University Museum in Sweden also matched the mold that could be used as a model for the pearl nautilus.
The pearl nautilus specimen from the Linnaeus Society in London is | Nikolaeva，et al. / Zootaxa（2015）
So in December of the same year, Nikolaeva and others published an official article in the Bulletin of Zoological Nomenclature, suggesting that the International Zoological Nomenclature Commission revoke all previous type specimens of the pearl nautilus and recommend that the specimens preserved in the Smithsonian Institution in Washington, D.C., be re-used as a new model of the pearl nautilus. In 2018, this proposal was echoed by the International Commission on Zoological Nomenclature, and the pearl nautilus finally had a model specimen.
The Model Specimen at the Smithsonian Institution | Nikolaeva，et al. / Bulletin of Zoological Nomenclature（2015）
There may be a small partner to see in the clouds, is not a specimen, just choose one is not good? In fact, the necessity of model specimens is not only to give taxonomists the correct description, identification or comparison of specimens, but also to trade control and protection of species. After all, the nautilus has a lot of fate.
Due to the perfect proportions of the Nautilus, it was sought after by collectors as early as the Renaissance era. To this day, the Nautilus is still one of the widely collected shell species, with considerable ornamental and collectible value. Together with the Fa snail, tangguan snail and Wanbao snail, it is known as the four famous snails.
16th century Nautilus cup | G.dallorto / Wikipedia
However, it is precisely because of this value that the Nautilus is heavily fished, so that its population has been assessed as threatened. Currently, all species of the Nautilus family are listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, whose international trade is restricted.
In China, The species in Appendix II of the Convention are treated as national second-level protected animals. Therefore, please consciously resist the trade in Nautilus products.
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