Not all adults feed at a high trophic level. Whale sharks (50 ft) are the
largest fish and feed on plankton and small fish while Great White sharks
(20 ft) are the largestcarnivorous fish and feed on sea lions, seals, and
large fish. Blue whales (100 ft) are the largest whale and feed primarily on
plankton and krill while the Sperm whale (45 ft) is the largest carnivorous
whale feeding on fish and very large squid. How does the location of each
animal's position in relation to the producers contribute to their size and
why do you suppose the plankton feeders are able to attain such large sizes
compared to the carnivores?
In the book ³Among Whales² by Dr. Roger Payne (pg. 33), he states that the
reason why baleen whales are so large, and the reason why they migrate such
long distances and fast for months at a time and have thick coats of
blubber, and communicate across oceans is because of their principal prey
Krill. Krill swarms can be more than 100 million tons which is more than
humanity¹s entire annual catch of fish from all oceans, therefore krill is
an incredible food source for several predators and can sustain the large
whales easily as they travel to the source using the above adaptations.
Sperm whales, for instance, follow their prey along deep water ridges and
are constantly hunting a depth. Their size could be more to do with their
adaptations to diving and feeding (stunning prey)? I am not sure. Make
sure you research WhaleNet¹s archives for more information on this
interesting subject or go to http://whale.wheelock.edu/howtofind.html to
locate data relating to this subject.
I hope this helps you. Your questions are very good. If you find more
details on this subject please let me know.
Ocean Alliance (Whale Conservation Inst. & the Voyage of the Odyssey)
191 Weston Road, Lincoln, MA 01773
781.259.0423 ext. 14 fax 259.0288
Please support our efforts to conserve whales and their ocean environment
through research and education :)
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