When you're a Northern fur seal (note the northern part of their name), frigid weather like we're having now is a field day. Cordova and Ursula, two Northern fur seal females, with a primary habitat off of Alaska, have a decided perkiness and excitement to the near-zero weather. On the other hand, Zoe and Sierra, two California sea lion pups, are not budging from their indoor pool!

Cordoba shows the secret of how a skinny seal with no blubber can stay warm in polar water. Her fur is the second thickest in the world with 300,000 hairs per square inch.

Marine mammal trainer Jamie Mathison is greeted by Cordova, an excited adult female fur seal, which was energized by the frigid temperatures.

Remarkably, Northern fur seals unlike most other polar seals have almost no blubber. Cordova and Ursula, both adults, weigh just 78 and 93 pounds each. What they do have is the second thickest fur in the world with nearly 300,000 hairs per square inch in a luxurious, multi-layer coat. They spend hours each day keeping it clean so that insulates properly. (It's even cold out now than when an ice sculptor made frosty fur seals for New Year's Eve celebrations!)

Meanwhile,  Zoe, a female California sea lion pup, lived up to her reputation of being a California girl when she and another sea lion pup refused to go outside this week in Boston’s 10-degree temperatures. Instead Zoe enjoyed a little soccer in the hallway of the New Balance Foundation Marine mammal Center.

It's going to be another chilly weekend, so come duck into the Aquarium where it's nice and toasty at some of our tropical exhibits—like The Trust Family Foundation Shark and Ray Touch Tank.