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Fish inner ear otolith size and bilateral asymmetry during development
1Zoological Institute, University of Stuttgart-Hohenheim, Stuttgart, Germany.
Hearing Research
|July 31, 1998
Summary
Larval fish otolith asymmetry, specifically lapilli, increased when stationary due to yolk sacs, but decreased upon free swimming. This suggests otolith size is regulated by gravity.
Area of Science:
- Developmental biology
- Otolith morphology
- Fish biology
Background:
- Inner ear otoliths (lapilli and sagittae) are crucial for balance and development in fish larvae.
- Larval development involves significant changes in body mass and orientation, influenced by factors like yolk sacs.
Purpose of the Study:
- To investigate the impact of larval positioning and water circulation on otolith size and bilateral asymmetry during ontogeny.
- To determine if environmental factors influence the development of otolith asymmetry in cichlid fish larvae.
Main Methods:
- Larval cichlid fish were raised in controlled aquarium conditions, with two groups: 'shifted' (random circulation) and 'stationary' (lying on sides due to yolk sacs).
- Otolith size and bilateral asymmetry (lapilli and sagittae) were measured throughout larval development from hatching to free-swimming stages.
Main Results:
- No significant differences in general development or otolith size were observed between shifted and stationary groups.
- Lapillar asymmetry significantly increased in stationary larvae during early development but decreased dramatically once they became free-swimming.
- Saccular otolith asymmetry remained low in both groups throughout development.
Conclusions:
- Larval positioning relative to the gravity vector significantly influences lapillar asymmetry development.
- Otolith size regulation may involve a feedback mechanism responding to gravitational cues.
- Environmental factors, such as larval orientation, play a role in inner ear development.