scholarly journals Defence behind the ramparts: Spicule armament against specialist predators in a subtidal habitat-forming ascidian

2018 ◽  
Vol 507 ◽  
pp. 31-38 ◽  
Author(s):  
Xavier Turon ◽  
Jessica R. Holan ◽  
Andrew R. Davis
Keyword(s):  
Subtidal Habitat ◽  
Specialist Predators

Design of experimental food patches to measure foraging intensity for octopus: a case study with the giant Pacific octopus Enteroctopus dofleini

2020 ◽  
Author(s):  
Stephanie Chancellor ◽  
David Scheel ◽  
Joel S Brown
Keyword(s):  
Predation Risk ◽  
Foraging Behaviour ◽  
Habitat Preferences ◽  
High Tide ◽  
Intertidal Habitat ◽  
Camera System ◽  
Subtidal Habitat ◽  
Enteroctopus Dofleini ◽  
Nontarget Species

ABSTRACT In a study of the foraging behaviour of the giant Pacific octopus Enteroctopus dofleini, we designed two types of experimental food patches to measure habitat preferences and perceptions of predation risk. The first patch successfully measured giving-up densities (GUDs), confirmed by octopus prey presence and higher foraging at sites with historically greater octopus presence. However, nontarget foragers also foraged on these experimental food patches. Our second floating patch design successfully excluded nontarget species from subtidal patches, and from intertidal patches at high tide, but allowed for foraging by E. dofleini. The second design successfully measured GUDs and suggested that octopus preferred foraging in a subtidal habitat compared to an intertidal habitat. We ascribe the higher GUD in the intertidal habitat to its higher predation risk relative to the subtidal habitat. The second patch design seems well suited for E. dofleini and, in conjunction with a camera system, could be used to provide behavioural indicators of the octopus's abundance, perceptions of habitat quality and predation risk.

scholarly journals Development and Interrogation of a Transcriptomic Resource for the Giant Triton Snail (Charonia tritonis)

2021 ◽  
Author(s):  
AH Klein ◽  
CA Motti ◽  
AK Hillberg ◽  
T Ventura ◽  
P Thomas-Hall ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Cell Signalling ◽  
Natural Populations ◽  
Olfactory Receptors ◽  
Gill Tissue ◽  
Abundant Species ◽  
Population Outbreaks ◽  
Coral Reef Ecosystems ◽  
Specialist Predators ◽  
G Protein Coupled

AbstractGastropod molluscs are among the most abundant species that inhabit coral reef ecosystems. Many are specialist predators, along with the giant triton snail Charonia tritonis (Linnaeus, 1758) whose diet consists of Acanthaster planci (crown-of-thorns starfish), a corallivore known to consume enormous quantities of reef-building coral. C. tritonis are considered vulnerable due to overexploitation, and a decline in their populations is believed to have contributed to recurring A. planci population outbreaks. Aquaculture is considered one approach that could help restore natural populations of C. tritonis and mitigate coral loss; however, numerous questions remain unanswered regarding their life cycle, including the molecular factors that regulate their reproduction and development. In this study, we have established a reference C. tritonis transcriptome derived from developmental stages (embryo and veliger) and adult tissues. This was used to identify genes associated with cell signalling, such as neuropeptides and G protein-coupled receptors (GPCRs), involved in endocrine and olfactory signalling. A comparison of developmental stages showed that several neuropeptide precursors are exclusively expressed in post-hatch veligers and functional analysis found that FFamide stimulated a significant (20.3%) increase in larval heart rate. GPCRs unique to veligers, and a diversity of rhodopsin-like GPCRs located within adult cephalic tentacles, all represent candidate olfactory receptors. In addition, the cytochrome P450 superfamily, which participates in the biosynthesis and degradation of steroid hormones and lipids, was also found to be expanded with at least 91 genes annotated, mostly in gill tissue. These findings further progress our understanding of C. tritonis with possible application in developing aquaculture methods.

A novel approach to measuring subtidal habitat complexity

2007 ◽  
Vol 353 (2) ◽  
pp. 279-286 ◽  
Author(s):  
Thomas A. Wilding ◽  
Craig A. Rose ◽  
Martin J. Downie
Keyword(s):  
Habitat Complexity ◽  
Subtidal Habitat ◽  
Novel Approach

scholarly journals Prey community structure affects how predators select for Müllerian mimicry

2012 ◽  
Vol 279 (1736) ◽  
pp. 2099-2105 ◽  
Author(s):  
Eira Ihalainen ◽  
Hannah M. Rowland ◽  
Michael P. Speed ◽  
Graeme D. Ruxton ◽  
Johanna Mappes
Keyword(s):  
Prey Species ◽  
Generalization Test ◽  
Parus Major ◽  
Warning Signal ◽  
Specific Model ◽  
Müllerian Mimicry ◽  
Effective Community ◽  
Mullerian Mimicry ◽  
Specialist Predators ◽  
Signal Accuracy

Müllerian mimicry describes the close resemblance between aposematic prey species; it is thought to be beneficial because sharing a warning signal decreases the mortality caused by sampling by inexperienced predators learning to avoid the signal. It has been hypothesized that selection for mimicry is strongest in multi-species prey communities where predators are more prone to misidentify the prey than in simple communities. In this study, wild great tits ( Parus major ) foraged from either simple (few prey appearances) or complex (several prey appearances) artificial prey communities where a specific model prey was always present. Owing to slower learning, the model did suffer higher mortality in complex communities when the birds were inexperienced. However, in a subsequent generalization test to potential mimics of the model prey (a continuum of signal accuracy), only birds that had foraged from simple communities selected against inaccurate mimics. Therefore, accurate mimicry is more likely to evolve in simple communities even though predator avoidance learning is slower in complex communities. For mimicry to evolve, prey species must have a common predator; the effective community consists of the predator's diet. In diverse environments, the limited diets of specialist predators could create ‘simple community pockets’ where accurate mimicry is selected for.

Emergent Facilitation among Predators on Size-Structured Prey

2013 ◽  
Author(s):  
André M. de Roos ◽  
Lennart Persson
Keyword(s):  
Life History ◽  
Prey Species ◽  
The Other ◽  
Positive Interactions ◽  
Predator Species ◽  
Life History Stages ◽  
Specific Predator ◽  
Specialist Predators

This chapter discusses a variety of positive interactions between predators foraging on different stages of the same prey species, which all emerge owing to the biomass overcompensation that may occur in prey life history stages in response to increased mortality. These interactions include emergent facilitation of specialist predators by generalists that forage on the same prey individuals as the specialists, but in addition forage on smaller or larger prey individuals as well. Furthermore, the chapter shows that two predators that specialize on different life-history stages of prey can facilitate each other to the extent that one predator relies on the presence of the other for its persistence. A stage-specific predator may act as a catalyst species, which promotes and in fact is necessary for the invasion of another predator species, but is subsequently outcompeted by the latter.

Arthropod entrapment increases specialist predators on a sticky crop and reduces damage

2019 ◽  
Vol 137 ◽  
pp. 104021 ◽  
Author(s):  
Peter N. Nelson ◽  
Hannah J. Burrack ◽  
Clyde E. Sorenson
Keyword(s):  
Specialist Predators

The Millipede-Predation Behavior of Promecognathus and Exceptional Cyanide Tolerance in Promecognathus and Metrius (Coleoptera: Carabidae)

2020 ◽  
Author(s):  
Brandt P Weary ◽  
Kipling W Will
Keyword(s):  
Hydrogen Cyanide ◽  
Natural Habitat ◽  
Chemical Defenses ◽  
Carabid Beetles ◽  
High Tolerance ◽  
Tolerance Level ◽  
Detoxification Mechanism ◽  
Enclosed Chamber ◽  
Predatory Insects ◽  
Specialist Predators

Abstract Promecognathus (Carabidae) includes beetles that are specialist predators whose prey are polydesmidan millipedes that produce highly toxic hydrogen cyanide and benzaldehyde as a defense, and it is unknown how Promecognathus overcomes these chemicals. We observed Promecognathus laevissimus (Dejean, 1829) and P. crassus (LeConte, 1868) in the laboratory and found that they did not use behaviors to avoid the chemical defenses of their prey, Xystocheir dissecta (Wood, 1867) (Polydesmida: Xystodesmidae). We tested benzaldehyde as a feeding deterrent and found noticeable deterrence in all carabid beetles tested except Promecognathus species and Metrius contractus (Eschscholtz, 1829). A total of 18 carabid species were exposed to cyanide vapors in an enclosed chamber for 10 min to determine their relative tolerances. Promecognathus and M. contractus were unaffected by HCN exposures 7–15 times greater than quantities that knocked down all other species. Promecognathus laevissimus and M. contractus were then exposed to high levels of HCN for 2 h, and while individuals of M. contractus succumbed, all P. laevissimus were still moving after 2 h. It is possible that Promecognathus evolved a high tolerance to cyanide as part of a suite of adaptations related to millipede predation. However, we have no plausible explanation for the high tolerance in Metrius, for which there is no evidence of millipede feeding. This is the first documented case of predatory insects that exhibit high tolerance and potential resistance to cyanide. Possibly, these beetles have a detoxification mechanism that is not cyanide specific, as their tolerance level far exceeds any dose they would encounter in their natural habitat.

Termitivore or detritivore? A quantitative investigation into the diet of the East African caecilian Boulengerula taitanus (Amphibia: Gymnophiona: Caeciliidae)

2004 ◽  
Vol 54 (1) ◽  
pp. 45-56 ◽  
Author(s):  
G. John Measey ◽  
Olivier Gaborieau
Keyword(s):  
Organic Matter ◽  
Stomach Contents ◽  
Gut Contents ◽  
Generalist Predators ◽  
East African ◽  
Quantitative Investigation ◽  
Soil Macrofauna ◽  
Taita Hills ◽  
Specialist Predators ◽  
African Genus

AbstractMost caecilians are thought to be generalist predators of soil ecosystem engineers (earthworms, termites and ants), but it has been suggested that members of the East African genus Boulengerula are specialist predators. Surprisingly, in the only detailed study of diet of any Boulengerula, the authors speculated that B. taitanus is partly detritivorous, based on the large amount of organic matter found in the alimentary canal. Here we test the conflicting hypotheses that B.taitanus is a termitivore or detritivore, using the stomach and gut contents of 47 specimens collected in the Taita Hills, Kenya. Termites and earthworms contribute most significantly to diet by number and mass, respectively. These constitute the major dietary items, together with dipteran larvae and other soil macrofauna. Contents of the intestine are mostly soil and organic matter originating from prey items. The mass content of the intestines averages 69% of total gut contents, and is significantly greater than identifiable stomach contents. The null hypotheses that B. taitanus is a generalist and a predator are not rejected.

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