Subject: Fin whales

Lindsay J Porter (h9390327@hkucc.hku.hk)
Thu, 9 Apr 1998 09:58:40 +0800 (HKT)

>hi my friend needs some info on finback whales


from
http://www.oit.itd.umich.edu/bio/Chordata/Mammalia/Cetacea/Balaenopteridae.shtml

Balaenopteridae

rorquals

This family includes 6 species placed in 2 genera. It includes minke,
Bryde's, sei, fin, humpback, and blue whales. These
range in size from the relatively small minke whale, about 8-10 m in length,
to the giant blue whale, at 20 - 28 m length and
almost 200,000 kg weight. The shape and color of the body, and the size and
shape of fins, varies considerably among
species. A shared external trait is the presence of deep longitudinal
grooves in the skin, running over the entire throat and
chest. 

The skulls of these mysticetes can be recognized by a combination of the
following technical characteristics: the nasals and the
nasal processes of the premaxillae extend backward beyond the supraorbital
processes of the frontals; the nasals are reduced
in size; the frontals are small and barely or not exposed on the dorsal
surface; the supraoccipital extends forward beyond the
zygomatic process of the squamosal; the rostrum is broad and flat. 

The baleen plates of rorquals are short and broad. These species feed by
gulping large quantities of water and straining
crustaceans and fish by shooting the water out between the baleen plates.

Rorquals feed in cold currents at high latitudes during the summer, mostly
on the eastern sides of the oceans. Some species
range mostly offshore, others are more often found in coastal waters. Their
food is primarily krill, euphausiid crustaceans,
which congregate near the surface in cold water. Blue whales eat little but
euphausiids; other species have a broader diet,
even including some fish. During the fall, most species migrate toward
equatorial latitudes. They fast for several month, living
by metabolizing blubber.

Rorquals are usually seen in groups ("pods") of 2-5 individuals. Their
populations have been much reduced by whaling, and
most are now fully protected by international treaty.

The Fin whale Balaenoptra physalus
Approx. 24-27 m in length, the Fin whale is usually found in pods of three
to seven invividuals - although single or pairs have been encountered.  Once
sexual maturity is obtained - between 6-12 years old - Fin whales reproduce
every two to three years, usually in teh winter in temperate regions.  The
species tends to move towards the poles every spring and to the  equator in
the autumn - populations can be found throughout the worlds oceans.  Fin
whales can dive to  230m and also breach (unlike most rorquals).  Probably
the fastest of rorquals (although recent evidence suggests that Sei  whales
may be quicker) - with burst speeds of 32km per hour recorded.  Fin whales
eat a variety of prey - krill, invertebrates, squid, herring - and are
predated themsleves by killer whales and were a commercially important
species in the whaling industry.


best wishes
Lindsay J Porter
email h9390327@hkucc.hku.hk
Dolphin Research Group
The Swire Institute of Marine Science
The University of Hong Kong
Cape d'Aguilar
Hong Kong
website: http://www.webdivers.co.uk/dolphin/index.html