As opposed to toothed whales, which form social groups and protect each other from predators, the baleen whale is less social. The only real bond is between a mother and her calf, and the mother will fiercely protect the calf. Other baleen whales, however, don't provide any defensive help to fellow baleens in trouble.
When attacked by a bigger whale, humpback whales thrash around, trying to avoid the predator's bite, while a Bryde's whale attempts to outswim its nemesis. When it comes to fight or flight, a toothless whale usually seems to choose flight.
The baleen whale's greatest threat, however, is man. Commercial whaling has threatened baleen whales for centuries. Whale oil, made by heating a whale's blubber, was known as "liquid gold," and could be used in everything from makeup to lamps. As we mentioned, right whales were targeted for their abundant blubber and oil, and when those whales were hunted to near extinction, whalers went after other species of baleens.
While both toothed and baleen whales were victims of the whaling industry, baleen plates had some additional uses in the marketplace. Because the material is both strong and flexible, it was used to make such items as corsets, hoop skirts and whips (which is where the phrase "getting a whaling" comes from). The bristles of the plates were used to make brushes and upholster furniture.
By the time the International Whaling Commission (IWC) banned commercial whaling in 1986, no more than 5 percent to 10 percent of some whale populations remained [source: Carwardine et al.]. At least half a million fin whales and a quarter million humpbacks were killed, while northern right whales numbered only 300 at one point [source: Carwardine et al.].
But with the IWC's protective measures, baleen whale populations are generally back on track, although whales are still being killed. The IWC ruling allowed for some exceptions, including protection for native tribes who practice whaling and whales caught for scientific research, the latter being a loophole that Japan has exploited to increase whaling practices [source: Carwardine et al.].
In addition to whaling, baleen whales are still vulnerable to getting caught and tangled in fishing nets and to being struck by boats. How long baleen whales live when they're not killed by predators is unknown. Blue whales are estimated to live 30 to 90 years, and fin whales might live 90 to 100 years.
To learn more about these filter-feeding whales, take a look at the links and related HowStuffWorks articles on the next page.