The scientific order Cetacea includes all whales. This order is further
divided into three suborders.
1. Odontoceti (toothed whales).
The toothed whales include dolphins, porpoises, beluga
whales, beaked whales, and sperm whales.
2. Mysticeti (baleen whales).
The baleen whales include blue whales, gray whales, and right whales.
3. Archaeoceti.
The
archaeocetes are an extinct group of whales, of which only fossils
remain (Barnes, 1990).
B. Family--Delphinidae.
Dolphins and their immediate
kin are included in the scientific family Delphinidae. This family
is represented by about 30 species,
including
common dolphins, pilot whales, killer whales, and false killer
whales.
C. Genus, species--Tursiops truncatus.
Although biochemical
evidence supports the existence of several geographical races,
most scientists currently recognize only
one species of bottlenose
dolphin (Klinowska, 1991).
Here's a classroom activity appropriate
for grades 4 - 8 - Latin Lingo!D. Fossil Record.
Many scientists
believe that early whales arose 50 million years ago from (now
extinct) primitive mammals that ventured
back into
the sea (Barnes, 1990). Two small rod-shaped pelvic bones,
buried deep in the body muscle of toothed whales, may
be remnants of
the hind limbs of these primitive mammals (Rommel, 1990).
Modern
forms of both odontocetes and mysticetes appear in the fossil record
five to seven million years ago.
The genus Tursiops first appears
in the fossil record about five million years ago (Barnes, 1990).
