Blue Whale
Balaenoptera musculus


Other Names: Sulfur-bottom, Sibbald's Rorqual, and Great Northern Rorqual

Habitat: Offshore and occasionally inshore

Status: Endangered

Population: c.6,000-14,000

Threats: Unknown

Group Size: 1-2, sometimes larger gatherings at feeding grounds

Fin Position: Far behind center

Newborns: c.23' (7 m), c.2.5 tons

Adults: 78' - 88' (24-27 m), 100 - 120 tons

Diet: Krill or other crustaceans

Baleen: 270 - 395 plates each side


Description

Dorsal fin:

- some fins moderately falcate
- tips may be rounded or pointed
- some fins almost triangular
- tiny, stubby dorsal fin (variable) located three-quarters of way along back

Flukes:

- broad flukes, up to one-quarter of body length
- slight notch in middle
- slightly concave or straight trailing edges

Flippers:

- pointed tips may be lighter than rest of flippers
- long, slender flippers, up to one-seventh of body length

Head:

- raised splashguard in front of blowholes
- black baleen plates
- longest baleen plates may be 39 in (1 m) long
- throat grooves

Head (from above):

- 2 distinct blowholes
- flat rostrum
- broad, U-shaped head
- single longitudinal ridge runs from blowholes to near tip of snout

Other characteristics:

- broad, flattened head
- large splashguard
- variable pale gray or white mottling, mainly behind head
- pale blue-gray body color (variable)
- extremely thick tail stock
- long, streamlined body
- underside may be covered in tiny algae, so may appear yellowish, especially in polar waters
- pale blue-gray or white undersides
- 55 - 88 throat grooves, usually end at or behind naval
- both sides of mouth uniformly blue-gray


Behavior

- blowing and diving patterns vary according to whale's activity
- when relaxed, blows every 10 to 20 seconds for a total of 2 to 6 minutes, an then dives for 5 to 20 minutes
- probably dives to depths of up to 490 ft (150 m), but can go deeper
- can accelerate to speed of over 19 mph (30 km/h) when being chased, but usually much slower
- some individuals are easy to approach, while others can be difficult
- adults rarely, if ever, breach clear of the water; however, youngsters have been observed breaching, usually at an angle of about 45 , and landing on their stomachs or sides
- in some areas, most feeding seems to take place during the evening and early morning


Distribution

- patchily distributed worldwide, mainly in cold waters and open seas
- three main populations are recognized: North Atlantic, North Pacific, and southern hemisphere
- distribution not continuous across range
- most live in the southern hemisphere, but often seen in parts of California; Gulf of California (Sea of Cortez), Mexico; Gulf of St. Lawrence, Canada; and northern Indian Ocean
- only a few hundred left in North Atlantic
- may migrate long distances between low-latitude wintering grounds and high-latitude summering grounds
- population in the northern Indian Ocean may be resident year-round
- mainly found along edge of the continental shelf and near polar ice



TMMSN Galveston

TMMSN Corpus Christi

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This page was created by:Candice Orca Mottet