Peter_jaksa's Blog
Answers to questions
Posted By: Peter_Jaksa, Dr. Hawke on Friday, October 13, 2006
Hi Everyone,
Thank you for your questions and please keep them coming.
Question #1 from Allison Rex:
How can you tell how old a seal is?
Great question! Several researchers in the past have tried to figure out reliable methods of determining the age of Weddell Seals and have had some success. These attempts have included measuring how long it takes a pup to lose all of the umbilical cord, or measuring tooth wear. For our purposes we do not need to know the exact age of the seals (which would require knowing a seal’s birthday). We are more interested in knowing where the seals fit into three categories: pup, juvenile and adult. You can tell that a seal is a pup by its grey coat, which turns black in 3 to 4 weeks. The pups weigh approximately 25 kg at birth and 240 kg at 7 weeks. They rely on their mother for food and can be found lying next to her almost all the time. Juveniles and adults can be distinguished by their size and behaviours. Juveniles are larger than pups and live close to the ice-edge. They are new divers and cannot travel for long periods of time under water. Adults are found farther from the ice-edge as they are expert divers. They may weigh well over 500 kg and can often be found guarding a breathing hole.
However, there are a group of researchers at McMurdo station who have been keeping track of the seals for many years. If needed, we can contact them to find out if the know the seal’s real birthday.
Question #2 from Kathy Bosiak:
Are Weddell seals true seals or eared seals?
Weddell Seals are true seals, also known as earless seals. There are a few ways to distinguish between true seals and eared seals. A commonly known eared seal is the Sea Lion. Perhaps you have seen these mammals performing at shows at a local aquarium. They are the ones that you hear barking for a tasty treat while balancing on their hind flippers. This is one of the ways to tell an eared seal from a true seal. True seals cannot walk on their hind flippers and are often called crawling seals. Also, true seals do not bark. Instead they communicate through a combination of chirping, whistling and grunting. Another important characteristic of true seals is that they are very good swimmers compared to eared seals. And of course, as the name suggests, an earless seal like the Weddell Seal has no external ears.
Talk to you all again soon,
Peter Jaksa
PS. I hope you are all having as much fun as I am with this project!
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