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Abstract Phenotypic features define feeding selectivity in planktonic predators and therefore determine energy flow through food webs. In current‐feeding cnidarian hydromedusae, swimming and predation are coupled such that swimming also brings prey into contact with feeding structures. Fluid mechanical disturbances may initiate escape responses by flow‐sensing prey. Previous studies have not considered how fluid signals define the trophic niche of current‐feeding gelatinous predators. We used the hydromedusaClytia gregariato determine (1) how passive (sinking) and active (swimming) feeding behavior affects pre‐encounter responses of prey to the medusae‐induced fluid motion, and (2) how prey responses affect the medusae's ingestion efficiencies. Videography of the predation process showed that passive prey such as invertebrate larvae were ingested during both feeding behaviors, whereas flow‐sensing prey such as copepods escaped the predator's active feeding behavior, but were unable to detect the predator's passive sinking behavior and were ingested (KWX2= 19.8246, df = 4,p < 0.001). Flow visualizations using particle image velocimetry (PIV) showed fluid deformation values during passive feeding below threshold values that trigger escape responses of copepods. To address whether fluid signals mediate prey capture, we compared fluid signals produced by three hydromedusae with different diets.Aequorea victoriaandMitrocoma cellulariaproduced higher deformation thanC. gregaria(two‐way ANOVA,F2,52= 5.532,p= 0.007), which explains their previously documented negative selection for flow‐sensing prey like copepods. Through the analysis of hydromedusan feeding behaviors and pre‐encounter prey escapes, we provide evidence that fluid signatures shape the trophic niches of gelatinous predators.
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Tap dancing frogs: Posterior toe tapping and feeding in Dendrobates tinctorius
Abstract Animals have myriad adaptations to help them hunt and feed in the most efficient and effective manner. One mysterious behavior related to hunting and feeding is the posterior toe tapping behavior of some frogs. Biologists and hobbyists alike have long noticed this behavior, but there is little empirical data to explain its causes and consequences. To test the hypothesis that tapping is related to feeding and modulated by environmental context, we conducted a series of related experiments in the Dyeing poison frog,Dendrobates tinctorius. We first confirmed that tap rate was higher during feeding as has been observed in other species. Interestingly, this effect was heightened in the presence of a conspecific. We next asked whether frogs tapped less under conditions when prey were visible, but inaccessible. Finally, we asked whetherD. tinctoriusadjusted tap rate based on substrate characteristics and whether prey capture success was higher when tapping. In addition to confirming an association between tapping and feeding, our work demonstrates modulation of toe tapping based on social context, prey accessibility, and substrate characteristics. Based on our findings, we suggest that tapping could act to induce prey movement and thereby facilitate prey detection and capture by frogs.
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- Award ID(s):
- 2146058
- PAR ID:
- 10500835
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Ethology
- Volume:
- 130
- Issue:
- 7
- ISSN:
- 0179-1613
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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