Genetic variation at 21 gene-enzyme systems was studied in a sample of an adult population of Anisakis typica (Diesing, 1860) recovered in the dolphin Sotalia fluviatilis from the Atlantic coast of Brazil. The characteristic alleles, detected in this population, made it possible to identify as A. typica, Anisakis larvae with a Type I morphology (sensu Berland, 1961) from various fishes: Thunnus thynnus and Auxis thazard from Brazil waters, Trachurus picturatus and Scomber japonicus from Madeiran waters, Scomberomorus commerson, Euthynnus affinis, Sarda orientalis and Coryphaena hippurus from the Somali coast of the Indian Ocean, and Merluccius merluccius from the Eastern Mediterranean. Characteristic allozymes are given for the identification, at any life-stage and in both sexes, of A. typica and the other Anisakis species so far studied genetically. The distribution of A. typica in warmer temperate and tropical waters is confirmed; the definitive hosts so far identified for this species belong to delphinids, phocoenids and pontoporids. The present findings represent the first established records of intermediate/paratenic hosts of A. typica and extend its range to Somali waters of the Indian Ocean and to the Eastern Mediterranean Sea. A remarkable genetic homogeneity was observed in larval and adult samples of A. typica despite their different geographical origin; interpopulation genetic distances were low, ranging from D(Nei)=0.004 (Eastern Mediterranean versus Somali) to D(Nei)=0.010 (Brazilian versus Somali). Accordingly, indirect estimates of gene flow gave a rather high average value of Nm = 6.00. Genetic divergence of A. typica was, on average, D(Nei)=1.12 from the members of the A. simplex complex (A. simplex s.s, A. pegreffii, A. simplex C) and D(Nei)=1.41 from A. ziphidarum, which all share Type I larvae; higher values were found from both A. physeteris (D(Nei)=2.77)

The relationship between dental morphology, sex, body length and age of small cetaceans can be used to determine ontogeny, sexual dimorphism and geographical variation. The objective of this study was to determine the relationship between dental morphology, sex, body size and age. A total of 91 specimens of P. blainvillei and 80 specimens of S. fluviatilis accidentally captured in fisheries or stranded in northern Rio de Janeiro (21 masculine37'-22 masculine25'S), from September 1988 to November 1996 were analysed. The teeth root diameter in P. blainvillei was significantly different between the sex; the values for females were larger than males. In neither species aid we observed significant in variations dimension and number of teeth, thickness of dentine and cemental layers and in the maximum width of cement as a function of body size. Age was related to increases in tooth length, root and cingulum diameters, and maximum width of cement in individuals of P. blainvillei, and tooth and crown lengths and maximum width of cement in individuals of S. fluviatilis. The observation of a linear growth between maximum width of cement and age in both species indicates that the equations obtained can be used to estimate relative age in P. blainvillei and S. fluviatilis in northern of Rio de Janeiro.

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Age, growth and reproductive parameters related to the marine tucuxi are presented, as well as feeding habits and parasitism. The specimens' age ranged from zero (newborn) to 21 years for males and 0·5 to 30 years for females. In relation to the body dimension, length distributions were bell-shaped for both sexes with male marine tucuxi ranging from 86·0 to 200·0 cm in length and females from 117·5 to 198·0 cm. The body length of new-born and calves varied between 86·0 to 117·5 cm and the postnatal growth curve an asymptotic reached length of 191·0 cm. According to the relationship between age, body length and reproductive characteristics, male and female specimens were considered sexually mature when [ges ]6 years and body length [ges ]180·0 cm and [ges ]6 years and body length [ges ]160·0 cm, respectively. Males and females up to six years old represented around 80% of the captures, indicating a bias towards juveniles and individuals that have yet to reach sexual maturity. The youngest specimen with solid contents in the stomach was 119·0 cm in length and seven months old. The marine tucuxi feeds on neritic prey, preferentially on the teleost fishes Trichiurus lepturus and Porichthys porossisimus, and on the cephalopods Loligo sanpaulensis and L. plei. Back calculation of prey lengths indicated that fish ranged from 1·2 to 106·9 cm and cephalopods from 3·4 to 22·2 cm. The barnacle Xenobalanus globicipitis was recorded attaching to the caudal fin and the helminths Braunina cordiformis, Anisakis typica, Halocercus brasiliensis and Nasitrema sp. were found in the internal organs.

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