Abstract
Hatching size has been considered of great importance in the evolution of externally shelled cephalopods. However, our knowledge of how hatching size varies in response to biotic and abiotic factors is largely lacking. We present a comprehensive overview of hatching size in all known species of modern nautilids (225 specimens, representing eight species). Hatching size ranges from 22 to 33 mm, with the smallest hatchlings in Nautilus pompilius suluensis and the largest hatchlings in Nautilus belauensis. There is no significant difference in hatching size between males and females in the same species. In addition, hatching size does not affect the morphology of the embryonic shell; smaller hatchlings are identical in morphology to larger hatchlings in the same species. Although information pertaining to temperature and duration of embryonic development are limited, we conclude that there is no clear correlation between hatching size and the temperature at which embryonic development takes place. In contrast, there is a weak correlation between hatching size and the duration of embryonic development. In the Late Cretaceous nautilid Eutrephoceras for which data on hatching size are available, species in colder climates exhibit a larger hatching size than those in more temperate climates. A comparison of hatching size and adult size among modern nautilid species reveals a positive correlation, largely driven by N. pompilius suluensis, at one end of the spectrum, and N. belauensis, at the other. This relationship may be rooted in parental care strategy and/or predation pressure.
| Original language | English |
|---|---|
| Pages (from-to) | 1-17 |
| Number of pages | 17 |
| Journal | Lethaia |
| Volume | 55 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 13 Sept 2022 |
Bibliographical note
Funding Information:Acknowledgments. – We thank Morgan Chase and Andrew Smith (American Museum of Natural History) for CT-scanning a number of specimens. Yasunari Shigeta (National Museum of Nature and Science, Japan) is thanked for providing access to the specimens of N. pompilius in his care. Kazunori Hasegawa (National Museum of Nature and Science, Japan) is thanked for providing access to the specimens of N. pompilius suluensis in his care. Daisuke Aiba (Mikasa City Museum) is thanked for providing access to the specimens of N. pompilius in his care. Takenori Sasaki (University of Tokyo) is thanked for helping find a nautilus specimen. Ryoji Wani (Yokohama National University) and Christian Klug (University of Zurich) are thanked for providing constructive comments on the early draft. AT thanks Kei Sato (Kanazawa University) for fruitful discussions. AT was supported by a Grant-in-Aid for JSPS Research Fellow, Grant-in-Aid for Young Scientists (grant nrs. 20J00376 and 21K14028), and Showa Seitoku Memorial Foundation Biology Research Grant. KN was supported by Grant-in-Aid for Scientific Research (JSPS KAKENHI Grant nrs. 17J11417, 17K14413, and 19KK0088).
Funding Information:
We thank Morgan Chase and Andrew Smith (American Museum of Natural History) for CT-scanning a number of specimens. Yasunari Shigeta (National Museum of Nature and Science, Japan) is thanked for providing access to the specimens of N. pompilius in his care. Kazunori Hasegawa (National Museum of Nature and Science, Japan) is thanked for providing access to the specimens of N. pompilius suluensis in his care. Daisuke Aiba (Mikasa City Museum) is thanked for providing access to the specimens of N. pompilius in his care. Takenori Sasaki (University of Tokyo) is thanked for helping find a nautilus specimen. Ryoji Wani (Yokohama National University) and Christian Klug (University of Zurich) are thanked for providing constructive comments on the early draft. AT thanks Kei Sato (Kanazawa University) for fruitful discussions. AT was supported by a Grant-in-Aid for JSPS Research Fellow, Grant-in-Aid for Young Scientists (grant nrs. 20J00376 and 21K14028), and Showa Seitoku Memorial Foundation Biology Research Grant. KN was supported by Grant-in-Aid for Scientific Research (JSPS KAKENHI Grant nrs. 17J11417, 17K14413, and 19KK0088).
Publisher Copyright:
© 2022 Author(s).