||The Mammals of Texas -
Cetacea : Family
Balaenopteridae : Balaenoptera physalus (Linnaeus)
Description. A large, slender whale
similar to the blue whale but head
V-shaped in dorsal view, rather than U-shaped; dorsal fin
high and placed even with or posterior to anus, on
posterior one-fourth of body; pectoral fin about
one-ninth of total length; head flattened, with right
side more whitish than left; right lower jaw white, left
grayish to black; upperparts gray, underparts pure white;
grooves on throat numerous and extending beyond navel;
whalebone lead color with whitish or yellowish fringes,
45-90 cm long, and more than 400 blades on each side.
External measurements of an immature animal: total
length, 18 m; tip of snout to corner of mouth, 3.6 m;
expansion of flukes, 4.3 m. Old individuals attain a
length of 25 m or more; females average slightly larger
than males. Weight of a 21-m female, 59.4 metric tons.
Distribution in Texas.
Cosmomarine, but rare in Texas waters. One young
individual, 5.5 m long, was stranded on the beach at
Gilchrist, Chambers County, on February 21, 1951. This is
the only known Texas record. Fin whales are classified as
Habits. Fin whales are highly
migratory. The whales move to high latitude feeding
grounds during spring and summer and return to southerly,
temperate waters for mating and calving during autumn and
winter. As with other migratory baleen whales, northern
and southern hemisphere populations do not interbreed due
to asynchronous seasons.
Fin whales feed mainly on krill but
also eat schooling fish including herring, cod, mackerel,
pollock, sardine, and capelin. Fish are eaten more often
The reproductive habits of these whales
remain largely unknown; however, females are thought to
give birth only at 3-year intervals. Mating and calving
occur from November to March in temperate waters. The
gestation period is approximately 11 months and newborn
fin whales are about 6.4 m in length and weigh 1.8 metric
tons. The period of lactation lasts 6-7 months and after
weaning the young whales are approximately 12.2 m long.
Sexual maturity is reached at 6-12 years of age.
Illustration credit: Pieter