Whales are among the largest and most magnificent creatures to ever live on Earth. They are completely adapted to one environment, but wholly dependent upon another for their very life’s breath. This fascinating group of mammals can be found in every ocean basin, from the equator to the poles.
There are two suborders of whales: Odonoceti, the toothed whales, which includes dolphins and porpoises, and Mysticeti, the baleen whales. Both groups evolved from terrestrial mammals that “returned” to the sea many millions of years ago.
Ambulocetus, or the “walking whale” was a carnivorous mammal that lived in what is now Pakistan and India around 50 million years ago. Its hind limbs were adapted for swimming, and it probably moved through the water by undulating its spine the way modern whales and otters do.
Whales became fully marine 35 million years ago. At that point, their tiny hind limbs were not useful for moving on land, but may have been used during mating. Modern whales are not closely related to other marine mammals. Their closest modern relative is believed to be the hippopotamus.
Whales use sound to communicate underwater. Toothed whales can use sound waves for navigation (sonar) and even to stun or kill prey. The low-frequency sounds produced by baleen whales are sometimes emitted in song-like patterns, like those of the humpbacks, and can travel tens to thousands of miles underwater. [Click here to listen to a humpback whale song].
The whales’ sensitivity underwater sounds makes them vulnerable to noise pollution. A number of studies have linked use of sonar by the Navy to increased whale strandings and population declines.
Whales are threatened in other ways. Many of the large whale species were nearly hunted to extinction in the mid-20th century. In 1986, commercial whaling was banned, although some hunting is allowed for indigenous groups. However, Japan, Norway, and Iceland exploit loopholes in the law, and continue to hunt whales for food under the guise of “scientific research.”
At the 2010 meeting of the International Whaling Commission, more than 200 scientists and other experts spoke out against efforts by these three nations to lift the ban. In February 2011, the Sea Shepherd Conservation Society claimed a victory for whales when Japan’s whaling season was cut short, and the fleet recalled from Antarctica after confrontations with activists.
Check out this 2009 post for an amazing life-sized encounter with a blue whale, the largest animal to ever live on Earth.
American Museum of Natural History. “Getting A Leg Up On Whale And Dolphin Evolution: New Comprehensive Analysis Sheds Light On The Origin Of Cetaceans.” ScienceDaily 25 Sep. 2009. Web. 6 Apr. 2011.
Tyack PL, Zimmer WMX, Moretti D, Southall BL, Claridge DE, et al. (2011) Beaked Whales Respond to Simulated and Actual Navy Sonar. PLoS ONE 6(3): e17009. doi:10.1371/journal.pone.0017009
Marine Mammals Poster Giveaway
This month’s giveaway is an out-of-print NOAA poster of Marine Mammals of the Western Hemisphere. Every comment left in the month of May equals one entry. Every link or reference to this blog on your site equals two entries. The drawing will be held on the 1st of May, so start your entries now!
A Round of Words in 80 Days: Week One, Update #1
For this 80-day challenge, I have given myself an ambitious set of goals, described here. My goal is not to hit every milestone, but to figure out which ones work for me in the long run. Tune in for updates every Sunday and Wednesday, and wish me luck!
Danielle Meitiv is an oceanographer by training, an advocate for all things marine and a writer of science fiction and non-fiction. Danielle is also a huge fan and sales affiliate of Holly Lisle’s online courses: How to Think Sideways: Career Survival School for Writers, and How to Revise Your Novel. Follow @Danielle_Meitiv on Twitter, and on Facebook: Brave Blue Words, and Danielle Meitiv.