Fernandez, Cheryl Hyacinth (1995) Chemoreception studies in relation to feeding responses in the marine shrimps Penaeus indicus H. Milne Edwards and Metapenaeus dobsoni Miers. PhD thesis, Cochin University of Science and Technology.
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Chemoreception in relation to feeding and the various factors involved in the same in Penaeus indicus and Metapenaeus dobsoni were investigated under laboratory and field conditions by behavioural and ongrowing studies . The entire sequence of feeding behaviour in shrimps from appetitive behavioural pattern to the consumatory act of feeding can be released by chemical stimuli alone. The chemotactic indices, Db and Rb, developed were used to classify the feeding stimuli as attractant and repellent based on their chemotactic property. Analysis of extracts of natural food materials for both species showed that they are attractive to !.indicus and ~ . dobsoni, whereas the squid ink acted as a feeding repellent for shrimps. The feeding response increased with increase in extract concentration and decreased with squid ink concentrations. The major attractant and stimulant substances present in the extracts were free amino acids with 78.2% of the extract activity in !.indicus and 50 . 28% in ~ . dobsoni, and nucleotides. Soluble proteins and peptides, lipids and carbohydrates also evoke feeding response but at lower level . Among the various groups of aminoacid; neutral followed by basic amino acids and among nucleotides; Inosine Mono Phosphate (IMP) produced maximum feeding response. At the same concentration L-Amino acids were found more stimulatory than the corresponding DL-amino acid. The threshold concentration of L-amino acids ranged between 4 x 10-2M and 1 x 10-10M for P. indicus and 1.5 to 1 -10 x 10 M for ~. dobsoni, and in the case of DL-forms it is between 1 x 10-2M and 1 x 10-5 M for both species. Amino acids like lysine, methionine, glycine, alanine and proline in P. indicus and lysine, methionine, alanine, ii phenylalanine and leucine in M. dobsoni produced maximum feeding response and feed ingestion. Most of the amino acids have anyone of the feeding activity, but those like glycine and lysine acted differently as attractants, incitant and stimulant at progressively increasing concentrations. Environmental parameters like pH and salinity have pronounced influence on the chemoreception and feeding response in the shrimps, being chemotactically more active at pH between 7.0 and 9.0 and salinity between 15 and 25%. • The feed intake reduced by 50% at pH 6.0 and 10.0. The alertness towards feeding stimuli increased with the degree of starvation upto certain levels and thereafter decreased due to the physical weakness of the animal. The agar matrix bioassay served as a cheap and efficient method to screen a wide variety of attractants and stimulants . Flavouring the diets with potential natural and synthetic chemo attractants and stimulants reduced the time required' to attract the shrimps to the feed and to initiate ingestion activity . It also improved the palatability and acceptability and subsequently improved food intake, growth, survival, food assimilation efficiency, specific growth rate and food conversion. This marked increase in the food intake and growth could be due to the increased digestive activity of the pancreatic secretion and the resultant increase in appetite, The attractants and stimulants produced more or less the same pattern for ingestion activity as that elicited during behavioural trial. It also indicated that the ongrowing performance of various feeding stimuli could be predicted directly from the behavioural trial. iii The chemoreceptors most concerned with feeding seemed to be on the antennules, on the pereopods and on the mouth parts. Antennu1e chemoreceptors were involved in distance chemoreception and to mediate arousal and search for potential food . The mouth and leg receptors functioned mainly as contact chemoreceptors; involved in the seizure and ingestion activity and to some extent they are also involved in distance chemoreception. Morphologically distinct chemosensory sensi11a present on these appendages were the primary sites for chemoreception in these species . Both P.indicus and M.dobsoni differed significantly in their chemotactic response to different stimuli. Among the various stages of animals studied juveniles were chemotactically more active than the post-larvae and juveniles.
|Item Type:||Thesis (PhD)|
|Supervisor(s):||James, P S B R|
|Uncontrolled Keywords:||Chemoreception studies; feeding; marine shrimps; Penaeus indicus; Metapenaeus dobsoni|
Food and Feeding
Crustacean Fisheries > Prawn and Prawn fisheries
|Divisions:||CMFRI-Cochin > Marine Capture > Crustacean Fisheries|
|Deposited By:||Geetha P Mrs|
|Deposited On:||18 Jan 2011 14:47|
|Last Modified:||11 May 2012 11:46|
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