The role of sense organs in the feeding behaviour of Chinese perch

Experiments were conducted to identify the rules of the individual sense organs in the feeding behaviour of Chinese perch Siniperca chuatsi by determining the consumption of natural food after selective removal or blocking of eyes, lateral lines and olfactory organs, and also by observing the behavioural response to visual, mechanical and chemical stimulation by artificial prey. Chinese perch were able to feed properly on live prey fish when either eyes or lateral lines were intact or functional, but could scarcely feed without these two senses. Chinese perch recognized its prey by vision through the perception of motion and shape, and showed a greater dependence on vision in predation when both visual and mechanical cues were available. Chemical stimulation by natural food could not elicit any feeding response in Chinese perch, and gustation was only important to the fish for the last stage of food discrimination in the oropharyngeal cavity. The sensory basis of Chinese perch in feeding is well adapted to its nocturnal stalking hunting strategy. and also explains its peculiar food habit of accepting live prey fish only and refusing dead prey fish or artificial diets. (C) 1998 The Fisheries Society of the British Isles.

Ontogenia do sistema sensorial de pacu Piaractus mesopotamicus (Holmberg, 1887) (Characidae: Serrasalmidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Morfologia comparada dos ductos genitais femininos e gonópodos masculinos de caranguej.s Eubrachyura (Saint Laurent, 1980)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

ONTOGENETIC DEVELOPMENT OF SENSORY STRUCTURES ON THE ANTENNULES AND ANTENNAE OF THE GIANT RIVER PRAWN MACROBRACHIUM ROSENBERGII (DE MAN)

In this study the occurrence of sensory structures on the antennules and antennae of the giant river prawn Macrobrachium rosenbergii (De Man) during postembryonic ontogenetic development were examined. Larvae and postlarvae were obtained from hatchery recirculating tanks, juveniles from indoor nursery tanks, and adults from earthen grow-out ponds. The animals were fixed with Karnovsky fixative and dissected. Antennules and antennae were removed, metal-coated, and photodocumented using a scanning electron microscope. The antennules have aesthetascs and simple plumose and pappose setae; the antennae have simple, plumose and pappose setae. These structures increase in density, covered surface, and distribution during ontogeny and should be related to chemoreception and mechanoreception. The antennular statocyst that appears during larval stage VII of the giant river prawn has an array of sensory structures that enable the perception of chemical and tactile stimuli beginning with its early life stages. The ontogenetic changes observed allow an inference that initial-stage larvae, advance-stage larvae, juveniles, and adults have different capacities to exploit the environment.