| Home: Special status species: Fin whale: Natural history |
SPECIAL STATUS SPECIES: FIN WHALE (Balaenoptera physalus)
NATURAL HISTORY |
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| General |
| Taxonomy: |
Suborder
Mysticeti (Baleen Whales); Family Balaenopteridae
(Rorquals). This species is sometimes split into
two subspecies, one each in the northern and southern
hemispheres, on the basis of differences in body
size.14 The subspecies in the northern
hemisphere is B. p. physalus.
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| Appearance: |
Fin whales
are very large, and only the blue whale is larger.
Adults average approximately 20 m (65 ft); females
are slightly larger than males.1 They have a sleek
body with a falcate dorsal fin and a ridge leading
to the caudal fin. They have 50 to 100 ventral pleats
that extend from the throat along the belly. The body
is dark gray above and white or cream-colored below.
The lower jaw and baleen plates are dark gray on the
left side and white on the right side. There are V-shaped
chevron markings across the back behind the head. |
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| Feeding Behavior |
| Overview: |
Fin whales feed alone or in small
groups. Large loose aggregations may occur in prime
foraging areas. Based on information from tagged fin
whales, dives averaged 100 m and 6.3 min during foraging.15 The deepest dive was approximately
310 m and the longest dive was 17 min. In the Mediterranean
Sea, dives to at least 470 m have been recorded.16 |
| Prey Items: |
Fin whales
prefer krill (mainly Euphausia pacifica, Thysanoessa
longipes, T. spinifera, and T.
inermis).
They also consume large copepods (mainly Calanus
cristatus),
and schooling fish such as herring, walleye pollock,
and capelin. |
| Method of
Capture: |
Fin whales lunge
into prey schools and gulp large quantities of water
and prey. Large volumes of water and food can be taken
into the mouth because of the expandable, pleated
grooves in the throat. As the mouth closes water is
expelled through the baleen plates, which trap the
food on the inside near the tongue to be swallowed. |
|
| Reproduction |
| Overview: |
No distinct breeding
or calving grounds have been identified for this species
and little is known about the mating system. Fin whales
are known to occasionally hybridize with blue whales.
Male fin whales have been recorded making an intense
low-frequency call. The function of the call appears
to be related to mating and may be a male breeding
display.17. Much of the information provided below is based on a review by Reeves and colleagues1. |
| Time to Maturity: |
10 years or older in unexploited
populations; as early as 6 or 7 in exploited populations |
| Longevity: |
Up to 80 years |
| Breeding
Season: |
Calving and breeding
usually occurs in winter |
| Frequency
of Breeding: |
Females usually give birth every
2-3 years |
| Gestation
Period: |
11-12 months |
| Number of
Offspring per Pregnancy: |
One calf |
| Parental
Care: |
Maternal; female nurses calf
for 6-7 months |
| Mating
System: |
Probably polygamous;
males or small groups of males have been seen chasing
females, which may be a courtship behavior. |
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