Week 1: The Cetaceans: An Introduction to Whales, Dolphins and Porpoises
Whales, dolphins and porpoises are all grouped together and called cetaceans.
Diversity is perhaps the most striking hallmark of the cetaceans, with over eighty different species of whales, dolphins, and porpoises recognized today. Cetaceans range in size from the small four-five foot porpoises and dolphins to the largest animal ever to live on earth, the 80-110 foot blue whale.
Cetaceans inhabit most of the world’s oceans, some traveling thousands of miles each year between high latitude feeding areas and lower latitude breeding and calving areas, while others live year around in fairly restricted areas. Some cetaceans like the Amazon River dolphin even inhabit the world’s largest rivers.
Based on the presence or absence of teeth, cetaceans are generally divided into two groups or suborders, the Mysticetes (baleen whales) and the Odontocetes (toothed whales), which are explored in greater detail below.
General Information about Whales:
The size of cetaceans ranges from the small 4-5 foot porpoises and the critically Endangered Hector’s Dolphin (Cephalorhynchus hectori) to the blue whale (Balaenoptera musculus), the largest mammal to ever live on earth. In general, baleen whales tend to be larger than toothed whales, but the 60-foot male sperm whale is larger than many baleen whales, including the humpback whale, which averages about 40-45 feet in length.
Whales are generally long-lived mammals, but longevity differs between species and sometimes between sexes. Although the average lifespan of a humpback whale is currently unknown, they are believed to live at least as long as 50-60 years. Some species of whales, like the bowhead whale are now known to live as long as 200 years, so it is possible that humpback whales live much longer.
Vocabulary Words from Week One
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