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Abstract

Whales are mammals which have become entirely aquatic, though
there is every reason to believe that they have been derived from
land mammals. As in the case of the specialized ichthyosaurian reptiles, the aquatic environment has imposed upon whales a fish-like form; the head passes imperceptibly into the trunk without a constricted neck; the anterior limbs or flippers have lost all externa1
semblance to the typical marnmalian fore-limb; and the hind limbs
have disappeared, though internal skeletal vestiges still persist. A dorsal fin is generally present, but does not contain skeletal supports
as in the ease of fishes. The well-developed caudal fin has no skeleton,
and differs from the vertical tail of fishes in being prolonged laterally
into fleshy horizontal expansions, the flukes. The nostrils (blowhole,
single or double) are situated high upon the vertex of the head. The
eyes are small, the external part of the ear is almost non-existent
and has no pinna. Teeth are generally present at some stage in
the life history, but in whalebone whales the teeth disappear before
the end of foetal life. The blubber, which is characteristic of whales,
is a thick subcutaneous tissue containing fat, and is impregnated
with oil. The hairy covering, which is present in all mammals, is
reduced to a few isolated hairs in the region of the mouth, and the
body is naked and shiny. This group includes the largest animals
which have ever lived.

Item Type:	Article
Authors/Creators:	Pearson, Joseph
Keywords:	Royal Society of Tasmania, RST, Van Diemens Land, natural history, science, ecology, taxonomy, botany, zoology, geology, geography, papers & proceedings, Australia, UTAS Library
Journal or Publication Title:	Papers and Proceedings of the Royal Society of Tasmania
ISSN:	0080-4703
Collections:	Royal Society Collection > Papers & Proceedings of the Royal Society of Tasmania
Additional Information:	Copyright Royal Society of Tasmania
Item Statistics:	View statistics for this item

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