Function of maxillipeds and first oostegites in bopyrid isopods inferred from behavioural observations of Bopyrus crangorum infesting Palaemon serrifer

The morphology of female bopyrids is adapted to parasitism, but understanding the function of their thoracic and mouth appendages is hindered by their small size and cryptic lifestyle, limiting detailed examination. This study aimed to clarify the function of the first oostegites and maxillipeds in...

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Bibliographic Details
Published in:Journal of the Marine Biological Association of the United Kingdom 2024-08, Vol.104, Article e65
Main Authors: Burgos, Lorelie A., Itani, Gyo
Format: Article
Language:English
Subjects:
Abdomen
Appendages
Chambers
Crustaceans
Digital cameras
Dyes
Dynamic structural analysis
Embryogenesis
Embryonic development
Embryonic growth stage
Embryos
Females
Flapping
Functional morphology
Grooming
Isopoda
Morphology
Oostegites
Parasites
Parasitism
Shrimps
Thorax
Ventilation
Water currents
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Summary:The morphology of female bopyrids is adapted to parasitism, but understanding the function of their thoracic and mouth appendages is hindered by their small size and cryptic lifestyle, limiting detailed examination. This study aimed to clarify the function of the first oostegites and maxillipeds in bopyrid isopods infesting the branchial chamber of caridean shrimp through behavioural observations and morphological examination. We tested whether the movement of these structures was exclusive to ovigerous female parasites during brood ventilation. The results revealed that the beating of the maxillipeds and flapping of the first oostegites were not restricted to ovigerous females. However, the frequency of these movements was significantly higher in ovigerous females than in non-ovigerous females. The frequency of maxilliped beating increased with embryonic development, whereas that of flapping the first oostegites exhibited the opposite trend. Microscopic observation using dye showed that the movements of the maxillipeds and the first oostegites expelled residual dye from the female brood chamber through the dorsal surface or beneath the first oostegites. The dye was then transported by the water current generated by the scaphognathite of the host shrimp. These findings suggest that these structures not only facilitate ventilation but also serve as a grooming mechanism for female parasites, which is critical for embryonic survival. The results of the present study represent the first observation of embryo grooming in bopyrid isopods. This study also provides new information on the functional morphology of bopyrid isopods, which is important for understanding their ecological dynamics and adaptation to parasitism.
ISSN:0025-3154
1469-7769
DOI:10.1017/S0025315424000596