February 8, 2012 Weddell Seal’s Habitat
This journal is brought to you by:
- Mrs. Gillespie and her 5th grade Sparks students at St. Ann Catholic School
A Closer Look at… a Weddell Seal’s Habitat
Southern Most Mammal
Weddell seals hold the record for living further south than any other mammal.
They live in the Southern Ocean surrounding Antarctica.
Weddell seals are marine mammals that have two different habitats: one on land – or ice – and one in water. Although seals are able to easily dive into the water or ‘haul-out’ on ice whenever they wish – Weddells typically spend most of their time in the water between the months of February and September, and on ice between October and January. But that doesn't mean they are always hauled out or always in the water during these times.
Check out this graph to see how ‘Wedds’ (as everyone calls them down here) spend their time:
Soaking up the Sun on the ICE
It’s no beach vacation – but Weddell seals enjoy soaking up the sun in the Antarctic spring and summer (which is actually our fall and winter) on fast ice. Fast ice is floating sea ice that is attached to land. This ice is often shaped by the movement of the tides, which means that the tides often stress the ice, forming cracks in it. Any guesses why this would be a benefit to the Weddell seal?
Weddell seals use these natural cracks in the ice for breathing holes, to dive into the ocean and to ‘haul-out’ on the ice.
Check out this video from Dr. Terrie Williams, who also studies Weddell seals:
Video Credit: Terrie M. Williams
There are two important things that happen to ‘Wedds’ during spring and summer, making it necessary to spend more time on the ice.
Breeding season – when mother seals give birth to pups. Since ‘Wedds’ breed in generally the same area every year, it makes it easy for our team to find the seals.
Molting – when seals shed their fur to grow a new coat. Seals can complete the molt faster if their skin is warm, and the skin can get warmer if the seal is ‘hauled out’ in the sun than when it is underwater. This is especially true on sunny days, when we see LOTS of seals ‘hauled out’.
After all, wouldn’t you rather be outside on a warm day than a cold one?!
Warmer in the water???
What? How can that be? The temperature of the seals’ underwater home stays constant year-round, ranging between -1.8˚C - 4˚C (27.8˚F – 39.2˚F). Above the ice, during their winter months, the temperature is much colder – between -26˚C to -8˚C (-16˚F – 16˚F). Burrrr!!! The gusting winds on ‘land’ make the temperature feel even colder! I guess I’d prefer the consistent temperature of the water too! Weddell seals still have to come up to the surface to breathe during the long fall and winter months – but they don’t have to get out of the water if they don’t want to.
Check out this graph for a more in-depth look at where ‘Wedds’ spend their time, on ice or under water. Follow the bold line to see their natural pattern for hauling out: they are most likely to be hauled out when the line is high on the graph, and they are least likely to be hauled out when the line is low. The dotted and dashed lines show the likelihood of them being on the surface or diving. What do you notice about how ‘Wedds’ spend their time?
In reference to images provided by Jennifer Burns and Michelle Shero and those that were not labeled: The activity/animal depicted was conducted pursuant to NMFS Permit No 87-1851.