DIGESTIBILITY OF KRILL (EUPHAUSIA-SUPERBA AND THYSANOESSA SP) IN MINKE WHALES (BALAENOPTERA-ACUTOROSTRATA) AND CRAB-EATER SEALS (LOBODON CARCINOPHAGUS)

Apparent digestible efficiency (% DE) was studied by use of dietary Mn as an inert marker, in minke whales (Balaenoptera acutorostrata) and crabeater seals (Lobodon carcinophagus) which had been eating krill. M edian % DE in minke whales (n 5) eating krill of the genus Thysanoessa sp. (energy density (ED) 23.8 kJ/g) was 93 (range 87-93). Median % DE in crabeater seals (n 6) eating krill of the species Euphausia superb a (ED 20.8 kJ/g) was 84 (range 79-85), which is significantly lower th an the % DE of krill in minke whales (P = 0.008). Since the chemical c omposition in E. superba and in Thysanoessa sp. is similar, it is sugg ested that the complex multi-stomached system of minke whales, which c ontains both chitinase (EC 3.2.1.14)-producing as well as several othe r types of bacteria, is superior to the single-stomached system of cra beater seals with regard to krill digestion. It is worth noting, howev er, that the % DE of krill in the crabeater seal is still very high.