2025 Summer Undergraduate Research Program (SURP) symposium
Location
Dr. Ken Budke Family Auditorium, Schindler Education Center, University of Nothern Iowa
Presentation Type
Poster Presentation (UNI Access Only)
Document Type
poster
Keywords
Weberian Apparatus, Botia lohachata, cyprinoforms, paraffin-embedding, ossicles
Abstract
The Weberian apparatus (WA) is a hearing adaptation in otophysan fishes (Cypriniformes, Characiformes, Siluriformes, Gymnotiformes) that significantly enhances hearing ability. The WA is a critical adaptation for predator avoidance and prey detection that has never been lost in >11,000 species, indicating high evolutionary constraint to maintain functionality. The complex WA structure is composed of an auditory portion (modifications to the swim bladder, ear, and vertebral elements known as ossicles) and the support portion (modifications of additional vertebral elements). Cypriniform fishes exhibit an enormous amount of morphological variation, particularly in the supporting structures that are hypothesized to dampen noise. Previous research shows the genus Botia shows such variation normally only seen across the generic or familial levels. In this study, we examined Botia lohachata and compared it to previous morphological studies to identify differences in elements of the WA that could be significant for environmental adaptation. Botia lohachata is a tropical demersal fish native to freshwaters in South Asia in a range stretching from Pakistan to Bangladesh, and occupies niches including creeks with rocky and gravel bottoms, which indicate a moderate noise profile. To identify intraspecific variation in morphology, five adult fish were used. Methods of morphological examination included: micro-computed tomography (micro-CT) for a non-destructive view of the anatomy; paraffin embedding, sectioning, and quadruple staining for detailed histological analysis of tissues at 8μm (cross/frontal, horizontal/coronal, and sagittal planes); and whole mount clearing and double staining for examination of the skeletal elements in situ . Results showed that the WA in B. lohachata is unique, exhibiting a morphology not before seen in botid or cypriniform fishes. Most interestingly, B. lohachata exhibits extensive bony growth of the support structures around the ventral surface of the swim bladder, continuing posteriorly to nearly encapsulate the bladder, ending with the right and left sides fusing at the midline. These results support the hypothesis that B. lohachata occupies noisy conditions and may represent a preliminary evolutionary stage of swim bladder encapsulation in Botia fishes.
Start Date
1-8-2025 11:00 AM
End Date
1-8-2025 1:30 PM
Event Host
Summer Undergraduate Research Program, University of Northern Iowa
Faculty Advisor
Nathan Bird
Department
Department of Biology
Copyright
©2025 Eric Schaufelberger, Annalise Zeinemann, and Nathan C. Bird
File Format
application/pdf
Recommended Citation
Schaufelberger, Eric; Zeinemann, Annalise; and Bird, Nathan C., "Morphological Description of the Weberian Apparatus in the reticulate loach, Botia lohachata" (2025). Summer Undergraduate Research Program (SURP) Symposium. 11.
https://scholarworks.uni.edu/surp/2025/all/11
Morphological Description of the Weberian Apparatus in the reticulate loach, Botia lohachata
Dr. Ken Budke Family Auditorium, Schindler Education Center, University of Nothern Iowa
The Weberian apparatus (WA) is a hearing adaptation in otophysan fishes (Cypriniformes, Characiformes, Siluriformes, Gymnotiformes) that significantly enhances hearing ability. The WA is a critical adaptation for predator avoidance and prey detection that has never been lost in >11,000 species, indicating high evolutionary constraint to maintain functionality. The complex WA structure is composed of an auditory portion (modifications to the swim bladder, ear, and vertebral elements known as ossicles) and the support portion (modifications of additional vertebral elements). Cypriniform fishes exhibit an enormous amount of morphological variation, particularly in the supporting structures that are hypothesized to dampen noise. Previous research shows the genus Botia shows such variation normally only seen across the generic or familial levels. In this study, we examined Botia lohachata and compared it to previous morphological studies to identify differences in elements of the WA that could be significant for environmental adaptation. Botia lohachata is a tropical demersal fish native to freshwaters in South Asia in a range stretching from Pakistan to Bangladesh, and occupies niches including creeks with rocky and gravel bottoms, which indicate a moderate noise profile. To identify intraspecific variation in morphology, five adult fish were used. Methods of morphological examination included: micro-computed tomography (micro-CT) for a non-destructive view of the anatomy; paraffin embedding, sectioning, and quadruple staining for detailed histological analysis of tissues at 8μm (cross/frontal, horizontal/coronal, and sagittal planes); and whole mount clearing and double staining for examination of the skeletal elements in situ . Results showed that the WA in B. lohachata is unique, exhibiting a morphology not before seen in botid or cypriniform fishes. Most interestingly, B. lohachata exhibits extensive bony growth of the support structures around the ventral surface of the swim bladder, continuing posteriorly to nearly encapsulate the bladder, ending with the right and left sides fusing at the midline. These results support the hypothesis that B. lohachata occupies noisy conditions and may represent a preliminary evolutionary stage of swim bladder encapsulation in Botia fishes.
