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Further Investigation: Mammals Energy Acquisition

  1. Some of the largest animals on Earth eat food items that are low on the food chain. Research the largest ten vertebrate animals alive on Earth, and determine what they eat. Can you deduce any connection between the body size of an animal and its diet? Can you offer any explanations for such a relationship?
  2. Beaked whales and the narwhal all belong to the odontocete group of cetaceans. Like other odontocetes, they have hard teeth. Unlike other odontocetes, these species only use their teeth for ornamental displays. Research the natural history of these unusual odontocete whales, particularly how they acquire energy and nutrition without teeth.
  3. The human is merely one of many species of mammal extant today. How do modern humans acquire energy? How does this method differ from that of earlier humans 10,000 years ago?

<p><strong>Fig. 6.26.</strong> (<strong>B</strong>) Walrus (O<em>dobenus rosmarus</em>) skull</p>

  1. The long sharp tusks of a walrus appear quite menacing (Fig. 6.26 B). They roughly resemble the long teeth of extinct saber-toothed cats. Both are examples of elongated canine teeth. Are walruses closely related to extinct saber-toothed cats or is this a case of convergent evolution? Use your local library and the Internet to research the evolutionary relationship between these two groups. What do the terms convergent evolution and homoplasy mean?
  2. Most marine mammals live in cold environments or conditions colder than their optimal body temperature. They may have thick skin, blubber, or fur (or all three) to insulate their bodies and conserve heat energy. They also eat large quantities of high-energy food in order to keep warm. Now consider mammals in very different conditions. How might a mammal in a hot, dry desert environment keep cool? Research and describe some physiological or behavioral adaptations that might help some mammal species survive under these harsh conditions.

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Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.