- Award ID(s):
- 1941713
- NSF-PAR ID:
- 10216519
- Date Published:
- Journal Name:
- Integrative Organismal Biology
- Volume:
- 3
- Issue:
- 1
- ISSN:
- 2517-4843
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract A diagnostic characteristic of stingrays in the family Dasyatidae is the presence of a defensive, partially serrated spine located on the tail. We assessed the contribution of caudal spine morphology on puncture and withdrawal performance from two congeneric, co-occurring stingrays, the Atlantic stingray, Hypanus sabinus, and the bluntnose stingray, Hypanus say. Spines exhibited a high degree of morphological variability. Stingray spines were serrated along 50.8% (H. sabinus) or 62.3% (H. say) of their length. Hypanus say had a greater number of serrations along each side of the spine (30.4) compared with H. sabinus (20.7) but the pitch did not differ between species. We quantified spine puncture and withdrawal forces using porcine skin as a model for human skin. Puncture and withdrawal forces did not differ significantly between species, or within H. say, but withdrawal force was greater than puncture force for H. sabinus. We incorporated micro-computed tomography scanning to quantify tissue mineral density and found that for both species, the shaft of the spine was more heavily mineralized than the base, and midway (50%) along the length of the spine was more heavily mineralized than the tip. The mineralization variability along the spine shaft may create a stiff structure that can fracture once embedded within the target tissue and act as an effective predator deterrent.more » « less
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Figures Synopsis There is an evolutionary arms race between predators and prey. In aquatic environments, predatory fishes often use sharp teeth, powerful bites, and/or streamlined bodies to help capture their prey quickly and efficiently. Conversely, prey are often equipped with antipredator adaptations including: scaly armor, sharp spines, and/or toxic secretions. This study focused on the predator–prey interactions between the armored threestripe cory catfish (Corydoras trilineatus) and juvenile red-bellied piranha (Pygocentrus nattereri). Specifically, we investigated how resistant cory catfish armor is to a range of natural and theoretical piranha bite forces and how often this protection translated to survival from predator attacks by Corydoras. We measured the bite force and jaw functional morphology of P. nattereri, the puncture resistance of defensive scutes in C. trilineatus, and the in situ predatory interactions between the two. The adductor mandibulae muscle in juvenile P. nattereri is robust and delivers an average bite force of 1.03 N and maximum bite force of 9.71 N, yet its prey, C. trilineatus, survived 37% of confirmed bites without any damage. The C. trilineatus armor withstood an average of nine bites before puncture by P. nattereri. Predation was successful only when piranhas bit unarmored areas of the body, at the opercular opening and at the caudal peduncle. This study used an integrative approach to understand the outcomes of predator–prey interactions by evaluating the link between morphology and feeding behavior. We found that juvenile P. nattereri rarely used a maximal bite force and displayed a net predation success rate on par with other adult vertebrates. Conversely, C. trilineatus successfully avoided predation by orienting predator attacks toward their resilient, axial armor and behavioral strategies that reduced the predator's ability to bite in less armored regions of the body.
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Abstract Cleaning symbioses on coral reefs are mutually beneficial interactions between two individuals, in which a ‘cleaner’ removes and eats parasites from the surface of a ‘client’ fish. A suite of behavioural and morphological traits of cleaners signal cooperation with co‐evolved species, thus protecting the cleaner from being eaten by otherwise predatory clients. However, it is unclear whether cooperation between cleaners and predatory clients is innate or learned, and therefore whether an introduced predator might consume, cooperate with or alter the behaviour of cleaners.
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Abstract Teeth tell the tale of interactions between predator and prey. If a dental battery is made up of teeth that look similar, they are morphologically homodont, but if there is an unspecified amount of regional specialization in size or shape, they are morphologically heterodont. These are vague terms with no useful functional implication because morphological homodonty does not necessarily equal functional homodonty. Teeth that look the same may not function the same. Conical teeth are prevalent in fishes, superficially tasked with the simple job of puncture. There is a great deal of variation in the shape and placement of conical teeth. Anterior teeth may be larger than posterior ones, larger teeth may be surrounded by small ones, and patches of teeth may all have the same size and shape. Such variations suggest that conical dentitions might represent a single morphological solution for different functional problems. We are interested in the concept of homodonty and using the conical tooth as a model to differentiate between tooth shape and performance. We consider the stress that a tooth can exert on prey as stress is what causes damage. To create a statistical measure of functional homodonty, stress was calculated from measurements of surface area, position, and applied force. Functional homodonty is then defined as the degree to which teeth along the jaw all bear/exert similar stresses despite changes in shape. We find that morphologically heterodont teeth are often functionally homodont and that position is a better predictor of performance than shape. Furthermore, the arrangement of teeth affects their function, such that there is a functional advantage to having several smaller teeth surrounding a singular large tooth. We demonstrate that this arrangement of teeth is useful to grab, rather than tear, prey upon puncture, with the smaller teeth dissipating large stress forces around the larger tooth. We show that measurements of how shape affects stress distribution in response to loading give us a clearer picture of the evolution of conically shaped teeth.