Fine structural characteristics of the chorionic microspheres on the egg surface of the orb web spider Trichonephila clavata

The eggs laid by the orb web spider Trichonephila clavata must overwinter in bitterly freezing and dry conditions before hatching, but there does not seem to be any protection like a compact silk case covering the entire eggmass. Instead, the surface of the eggmass is completely coated with a milky...

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Bibliographic Details
Published in:Applied microscopy 2023, 53(1), , pp.1-11
Main Authors: Lee, Seung-Min, Moon, Myung-Jin
Format: Article
Language:English
Subjects:
Arthropods
Chemistry and Materials Science
Coatings
Eggcase
Eggmass
Eggs
Electron microscope
Electron microscopes
Ethanol
Freezing
Hatching
Materials Science
Microspheres
Morphology
Ovaries
Overwintering
Oviposition
Silk
Spiders
Surface structure
Transmission electron microscopy
Trichonephila clavata
Webs
자연과학일반
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Summary:The eggs laid by the orb web spider Trichonephila clavata must overwinter in bitterly freezing and dry conditions before hatching, but there does not seem to be any protection like a compact silk case covering the entire eggmass. Instead, the surface of the eggmass is completely coated with a milky coating called chorionic microspheres (CM). Therefore, we investigated the fine structural characteristics of CM to demonstrate their ecological importance. Although the diameter of CM in outer eggmass exhibits a significant variation, the chorionic surface is coated with a single layer of CM, characterized by a consistent diameter of approximately 2.3 µm. The surface structure of aggregated CM shows short papillary projections demonstrating segmental adhesion of mucous components. CM is insoluble in water but partially soluble in anhydrous ethanol, and its spherical structure is completely decomposed by hexafluoroisopropanol (HFIP), a strong organic solvent. Since our fine structural observations clearly show that CM is not derived from vitellogenic or choriogenetic processes, the CM adhesive coatings during ovipositional process appears to be equivalent to cocoon silk for various protective functions in silken eggcase.
ISSN:2287-4445
2287-5123
2287-4445
DOI:10.1186/s42649-023-00087-4