Showing papers by "Universidade Federal de Mato Grosso published in 1990"
TL;DR: Three piranha species seem to strongly influence use of habitat, social structure, and foraging mode of the fish communities, and defensive tactics of prey fishes were observed.
Abstract: The behaviour of three piranha species,Serrasalmus marginatus, S. spilopleura, andPygocentrus nattereri, and their prey fishes was studied underwater in the Pantanal region, Mato Grosso, Brazil. General habits, predatory tactics, feeding behaviour, and social interactions while foraging, as well as defensive tactics of prey fishes were observed.S. marginatus is solitary whereas the other two species live in shoals; their agonistic behaviour varies accordingly, the simplest being displayed by the solitary species. Predatory tactics and feeding behaviour also vary:S. spilopleura shows the most varied diet and highly opportunistic feeding strategy, which includes aggressive mimicry. The solitaryS. marginatus, besides fin and scale-eating, occasionally cleans larger individuals ofP. nattereri. Several cichlid species display defensive tactics clearly related to piranha attacks: tail protecting, watching, and confronting the predator are the most commonly observed behaviours. Piranhas seem to strongly influence use of habitat, social structure, and foraging mode of the fish communities.
140 citations
01 Jan 1990
6 citations
01 Jan 1990
3 citations
01 Jan 1990
1 citations
TL;DR: The transformation property under the Poincare group of local quantum mechanics is expressed by depending on a correspondence with the quantum field theory in terms of ten generators of infinitesimal transformations in the state-vector space for a simple example, in the continuum approximation which represents the finite momentum degree of freedom by a continuous density function as discussed by the authors.
Abstract: The transformation property under the Poincare group of the recently proposed local quantum mechanics is expressed by depending on a correspondence with the quantum field theory in terms of ten generators of infinitesimal transformations in the state-vector space for a simple example, in the continuum approximation which represents the finite momentum degree of freedom by a continuous density function. They "do not generate the representation of the Poincare group but seven of them generate the unitary representation of the group composed of the 4-dimensional translation and the 3-dimensional rotation around a universal timelike vector. The deviation from the Lorentz invarian ce is due to the finiteness of the momentum degree of freedom of the system and considered to have observable effects in ultrahigh energy phenomena.