. LENGTH IN METRES Text-fig. 13. Plot of foetal weight against length for 234 blue, fin and sei whales (black circles), nine humpback whales (white circles), and ninety-three porpoises (crosses = monthly mean values). Regression lines have been fitted by eye and the neonatal values for blue, fin and humpback whales are indicated. In the last 5 months of pregnancy the blue whale foetus grows in length from 1-3 to 7-0 m., corre- sponding to an increase in weight of 2480 kg. (from 20 to 2500 kg.) or 2-44 tons. In the last two months of pregnancy the average gain in weight is over 2 tons (420-2500
. LENGTH IN METRES Text-fig. 13. Plot of foetal weight against length for 234 blue, fin and sei whales (black circles), nine humpback whales (white circles), and ninety-three porpoises (crosses = monthly mean values). Regression lines have been fitted by eye and the neonatal values for blue, fin and humpback whales are indicated. In the last 5 months of pregnancy the blue whale foetus grows in length from 1-3 to 7-0 m., corre- sponding to an increase in weight of 2480 kg. (from 20 to 2500 kg.) or 2-44 tons. In the last two months of pregnancy the average gain in weight is over 2 tons (420-2500 kg). The gro\vth rate of the fin whale is of the same order of magnitude. In some individual blue whales the growth rate is prob- ably even greater; the largest blue whale foetus (PI. XIII, fig. 2) measured 7-46 m. and must have weighed about 2800 kg. (275 tons). Expressed in this way the foetal growth rate of the baleen whales is seen to be phenomenally rapid, and without parallel.
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Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
