February 8, 2012 What's on the Menu? The 'Diet' of a Weddell seal!
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- Ms. Toes and her K-3 CLUE students at Keystone Elementary
- Mrs. Gillespie and her 3rd grade Sparks students at St. Ann Catholic School
- Ms. Lane and her 2nd grade CLUE students at Grahamwood Elementary
- Students at St. Philomena Junior High in Peoria, Illinois
A Closer Look at … a Weddell Seal’s Diet
What does a Weddell seal eat? Let’s check out what’s on the menu!
What would you choose if you had to select from one of these tasty items on the menu?
You try it!
Create your own Weddell seal menu and share it with me on the 'Ask the Team' section of my web page here.
Let's look at some of these tasty treats!
The Antarctic Silverfish (Pleuragramma antarcticum)
The Antarctic Silverfish (Pleuragramma antarcticum) gets a ‘five star ranking’ from the Weddell. They are among the most common fish the Weddell eats, although, I’m not quite sure if it’s because the seals prefer the Silverfish – or because they’re very common in the Ross Sea. Either way, it’s most likely number one. As you can see in the picture, they live up to their name – they’re silver! But they also have a pinkish tint. I was surprised to learn that while the fish is alive it looks pinkish (with silver highlights), but after it dies it turns completely silver. These fish are less than a foot long (about 6-10 inches), and can be swallowed whole – up to over 100 in one dive by a Weddell seal. Ice fish, like the silverfish, also have a unique adaptation for living in such an extremely cold environment: they have an antifreeze protein in their blood which protects them in the frigid waters.
The Bald notothen (Pagothenia borchgrevinki)
The Bald notothen or ‘Borch’ – pronounced ‘bork’, for short – (Pagothenia borchgrevinki) is another tasty treat for a Weddell. These ice fish are less than a foot long and are yellowish in color with dark spots.
Weddell seals are crafty creatures. Scientists have observed them ‘capturing their prey’ by blowing air bubbles into ice holes to scare fish out. When the fish come out of their hiding places the seal quickly gobbles them up. ‘Borchs’ are often captured this way because they feed on animals under the ice.
A fish that finds itself in a seal’s belly a little less often is the Antarctic Cod, which is a really big fish. They can weigh over 150 pounds but most weight less than that – about 70 pounds! The reason seals hunt these less may be because of their size. It takes a lot of energy to get a fish that big up to the surface. And, the seal expends even more energy to thrash the fish around to get the meat; maybe that’s why these big fish are eaten a little less frequently.
Tentacles or Crustaceans anyone?
Other bite-sized morsels that can be swallowed whole are small squid, shrimp and krill. Weddell seals can gobble these guys up like popcorn.
You’ve heard the saying, 'You are what you eat'
Well that’s actually true! These scientists are using that idea to study the diet of Weddell seals. They collect whiskers, fur, blood and blubber samples from seals, so they can find out what the seal has been eating. What are they looking for, you ask? Good question! Each time a seal eats, chemical compounds from the food are left on various parts of their bodies – their fur, for example. Scientists are able to study those compounds and match them to particular prey. Then, knowing the rate that the seal’s fur grows, the scientists are able to estimate the seal’s long term eating patterns by analyzing the chemical compounds in the fur. Very interesting!