Saturday, December 16, 2006

Apple #211: Walruses

I saw something on Animal Planet the other day about how some people found a young, injured walrus and nursed him back to health. There were a lot of close-up shots of this young walrus. He had the pouchy front cheeks, the whiskers, and his skin looked smooth and he had an expression like a nice but slightly confused dog: What's are you doing? Will there be food?

I realized I didn't know all that much about walruses. Time to do a little appling.

  • Walruses live on both the Atlantic and Pacific shores. Pacific walruses are generally larger. They weigh, on average, around 2,000 pounds.
  • Walruses live in enormous groups, or herds, by the hundreds. Scientists say this makes them the most gregarious of all animals.

This is only part of a herd of walruses
(Photo from the NOAA Photo library, used at Gregory's page on walruses)

  • They group together as a way to keep warm, which is essential since they tend to live in pretty cold places, like off the coasts of Canada and Greenland, and in the Bering sea.
  • They also have a layer of blubber to keep them warm. Their blubber can be as much as 4 inches thick.
  • Even though walruses hang out together by the hundreds, they separate themselves into groups of males and groups of females.
  • They also develop hierarchies within the groups based on size, aggressiveness, and tusk length. Bigger walruses with longer, unbroken tusks are at the top of the social ladder, while smaller walruses with shorter or broken tusks are at the bottom. Walrus tusks can grow to be 30 to 39 inches long.
  • Walruses use their tusks for fighting and for getting in and out of the water from icy or rocky shores. This process of entering or exiting the water is referred to as "hauling."

This walrus has hauled himself out of the water to take a break in his search for food. Just relaxing on a big old pile of ice.
(Photo by Budd Christman of NOAA, and posted by the Landfast Ice Gallery)

  • Their foreflippers have all the same skeletal components as the arms of a land animal, but everything is shortened and slightly modified. In the water, walruses use their foreflippers for steering (for propulsion, they alternate strokes of their hind flippers), and on land, they use the foreflippers as front legs in walking.
  • Scientists have discovered that most walruses have slightly larger bones in their right flipper. This means that most walruses use their right flipper more often than the left.
  • In the water, walruses can reach speeds up to about 20 mph. They can stay underwater as long as 10 minutes without coming up for air.
  • Walruses may communicate with each other above water or below. Above water, they clack their teeth and whistle. Below water, they make clicking or knocking noises, tapping, and "bell-like sounds." You can listen to some walrus sounds here -- and in this one, I thought the gonging sound was a person playing a drum, but it's actually a walrus!
  • Walruses have a special throat muscle that keeps water from going down its throat when the mouth is opened.
  • They eat a lot of shellfish, like clams and sea cucumbers and crabs. They dive underwater to look for clams, but because the water is usually cloudy and dark, they sniff along the bottom and use their whiskers to find food. The technical name for their whiskers is vibrissae.
  • They might use their tusks to dislodge the clams, or some walruses also blow powerful jets of water at the sea floor to uproot the mollusks. Then they suck the soft-bodied animals out of their shells and swallow them whole. Adult walruses can eat anywhere from 3,000 to 6,000 clams at one sitting.

This walrus is snuffling out clams on the sea bed
(Photo from the BBC)

  • Walruses may also eat fish occasionally, but they like the shellfish best. If food is really scarce, they may scavenge from corpses of dead seals, but that's when times are hard in walrus-land.
  • There are, however, some rogue walruses who eat seals a lot. They are referred to as "habitual seal-eaters." I'm not kidding. They are usually male walruses, they're usually larger than other males, and they're recognizable as seal-eaters because their skin gets grease-stained from seal blubber. Sounds like these are the bad seeds in the walrus herd.

Then, of course, there's the musical walrus.
(If you want to know what the song means, read what John Lennon said about it.)

Sea World Education Department Resource, Walruses
Helen Briggs, "Most walruses are right-flippered," BBC News, October 22, 2003

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