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Shearing Tooth Morphology May Allow Sharks to Access Higher Trophic Levels at Smaller Sizes.
Sabrina Riverón1,2, Vincent Raoult3,4,5, David J Slip1,6
1Marine Predator Research Group, School of Natural Sciences Macquarie University North Ryde New South Wales Australia.
Ecology and Evolution
|July 31, 2025
Summary
Predator morphology, like tooth shape and body size, significantly influences prey selection and trophic niches. Different shark species demonstrate distinct feeding strategies based on their physical traits, impacting marine food webs.
Area of Science:
- Marine Biology
- Ecology
- Evolutionary Morphology
Background:
- Prey availability alone does not guarantee consumption; predators must detect, capture, and handle prey.
- Predator and prey morphology create biomechanical constraints, limiting functional accessibility of certain prey.
- Morphological factors such as tooth shape, body size, and mouth gape influence predator trophic niches.
Purpose of the Study:
- To assess how tooth shape and body length influence prey selectivity and trophic niche in two sympatric shark species.
- To compare the foraging strategies of the grey nurse shark (Carcharias taurus) with grasping teeth and the sevengill shark (Notorynchus cepedianus) with cutting teeth.
Main Methods:
- Stomach content analysis to determine prey selection.
- Stable isotope analysis (δ13C, δ15N, δ34S) of muscle and liver tissue to characterize isotopic niche.
- Comparison of feeding patterns in relation to body size for both shark species.
Main Results:
- Gape-limited grey nurse sharks shifted from teleosts to chondrichthyans as they grew.
- Non-gape-limited sevengill sharks consumed teleosts, chondrichthyans, and marine mammals irrespective of body size.
- Both species consumed prey from higher trophic levels with increased body length, with sevengill sharks accessing relatively higher trophic levels.
- δ13C and δ34S values were not significantly related to body length, suggesting morphology does not limit access to pelagic or benthic food webs.
Conclusions:
- Morphological characteristics, particularly dentition and gape, are crucial drivers of prey selection in large predators.
- These morphological traits facilitate resource partitioning among sympatric predators, influencing trophodynamics in marine ecosystems.
- Incorporating morphological factors is essential for understanding prey choice and marine food web dynamics.
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