Search results for "cannibalism"
showing 10 items of 27 documents
Toxicity of 3,4-dichloroaniline to perch (Perca fluviatilis) in acute and early life stage exposures
1993
Abstract The toxitity of 3,4-dichloroaniline to perch was investigated in order to compare the sensitivity of crucial life stages with common test fish like zebrafish. Although in the acute toxicity test perch were more sensitive by a factor of five, larval sensitivity was in the same range in both species as well as in other egg-laying species. In spite of different water temperature and size, the zebrafish is a good model to predict early life stage toxicity of 3,4-DCA to the compared European freshwater species. Perch larvae are not suited for early life stage tests, as they are sensible towards experimental conditions and perform early cannibalism.
Features of intercohort cannibalism of Vendace (Coregonus albula(L.)) under laboratory conditions
2012
Cannibalism in Vendace (Coregonus albula (L.)) was studied under laboratory conditions by exposing Vendace eggs (100) or newly hatched larvae (20) to an older individual in aquaria. Predation on the eggs was not detected whereas both biting and ingesting of newly hatched larvae were observed in 23% of older Vendace individuals. Small individuals (<100 mm in total length) were significantly more likely to attack larvae than larger individuals. Differences were also found in attack rates between individuals. The rate ranged from no attacks to attacks towards every larva exposed to the cannibalistic individual. These results confirm that intercohort cannibalism is neither an exceptional nor a …
‘Non humana viscera sed centies sestertium comesse’ (Petr. Sat. 141,7): Philomela and the Cannibal Heredipetae in the Crotonian Section of Petronius’…
2013
The connection between the themes of money and death is widespread in Petronius' Satyricon, and is definitely not limited to the Cena Trimalchionis, where it has been widely examined. The aim of my paper is to consider the peculiar form that the motif takes in the Crotonian section of Petronius' Satyricon, and its connections with the mythical memory of the Procne and Philomela story. The theme of corpses dismemberment appears at the end of the episode of the shipwreck, the one immediately preceding the Crotonian section, through Encolpius' reflections on the sepultura practice and the destiny of human bodies after our death (Petronius, Satyricon 115, 6-19); the same theme closes the introd…
A case of cannibalism in the false smooth snake Macroprotodon cucullatus on the island of Lampedusa
2020
A case of cannibalism in the false smooth snake Macroprotodon cucullatus on the island of Lampedusa
Female control of paternity in the sexually cannibalistic spider Argiope keyserlingi.
2000
Sexual conflict theory predicts an antagonistic coevolution, with each sex evolving adaptations and counter-adaptations to overcome a temporary dominance of the other sex over the control of paternity. Polyandry allows sexual selection to operate after mating has commenced, with male and female interests competing for control of fertilization. There are numerous examples of male control of paternity, but few studies have unambiguously revealed female control. Attributing variance in paternity to females is often difficult since male and female influences cannot be separated unambiguously. However, we show that polyandrous female orb-web spiders Argiope keserlingi (Arancidae) control the pat…
Neurobiological aspects of shamanism and sacrifice
2009
According to Winkelman, humans skilled in “soul yourneys” are termed as “shamans”: they are religious practitioners found in foraging societies around the world with antiquity at least as far back as the Middle/Upper Paleolithic transition. Shamans are able to enter into an “ecstatic” state of consciousness that is produced by drumming, chanting, dancing and a variety of other procedures including plant drugs. Altered states of consciousness must be understood in relation to biological capacities, as those related to endogenous neurotransmitters which also have external analogues, such as opioids/opiates and serotonin–like analogues. Recent findings in neurobiological studies support the ro…
Sperm competition and small size advantage for males of the golden orb-web spider Nephila edulis
2000
Sexual selection, through female choice and/or male‐male competition, has influenced the nature and direction of sexual size dimorphism in numerous species. However, few studies have examined the influence of sperm competition on size dimorphism. The orb-web spider Nephila edulis has a polygamous mating system and extreme size dimorphism. Additionally, the frequency distribution of male body size is extremely skewed with most males being small and few large. The duration of copulation, male size and sexual cannibalism have been identified as the significant factors determining patterns of sperm precedence in spiders. In double mating trials, females were assigned to three treatments: either…
Costs of courtship and mating in a sexually cannibalistic orb-web spider: female mating strategies and their consequences for males
2002
The costs of courtship and mating may include increased risks of predation, the transmission of pathogens, and a loss of foraging opportunities. Thus, a female's decision to tolerate a courting male will depend upon how these costs offset the benefits of mating, which will depend on her reproductive and nutritional status. While these costs may be similar for mated and unmated females, the benefits of mating will be less for mated than virgin females. However, the cost of lost foraging opportunities may be higher for females with fewer nutritional reserves necessary for forming eggs. We examined how these costs and benefits influence the courtship and mating behaviour of male and female orb…
A mate to die for? A model of conditional monogyny in cannibalistic spiders.
2012
Monogynous males in various species actively limit themselves to mating with a single female in their lifetime. Whereas previous models have considered monogyny as an obligate mating strategy, here we explore the potential of monogyny to evolve as a context-specific (conditional) behavior. Using a state-dependent dynamic game model based on the biology of the cannibalistic spider Argiope bruennichi, we confirm that conditional monogyny can evolve under broad conditions, including an even sex ratio. We predict that males should make a terminal investment when mating with large, virgin females, especially if population density is low and the encounter occurs late in the season. We encourage e…
A mate to die for? A model of conditional monogyny in cannibalistic spiders
2012
Monogynous males in various species actively limit themselves to mating with a single female in their lifetime. Whereas previous models have considered monogyny as an obligate mating strategy, here we explore the potential of monogyny to evolve as a context-specific (conditional) behavior. Using a state-dependent dynamic game model based on the biology of the cannibalistic spider Argiope bruennichi, we confirm that conditional monogyny can evolve under broad conditions, including an even sex ratio. We predict that males should make a terminal investment when mating with large, virgin females, especially if population density is low and the encounter occurs late in the season. We encourage e…