Water bears

 September 8

Early in the trip we saw a lot of icebergs in open water. As we moved north there was a lot of sea ice. Yesterday there was essentially no ice, perhaps because we were sheltered or because there was enough current to keep ice from forming. Today there was newly forming ice but icebergs also. 

The crew navigated through a set of narrow channels named Hell’s Gate into the Jones Bay, which runs north of Devon Island. We could not return by the Wellington Channel where we sailed three days ago, as the ice has already filled it in.  Our intended course was interrupted to detour closer to a polar bear swimming along the shore of Kent Island. 

We spent the afternoon in Walrus Fiord (fiord is the local spelling) where we saw many walrus and bearded seals resting on the fragments of sea ice. We also saw “sea butterflies” (tiny swimming sea snails that flutter near the surface) and some comb jellies. 

Why “water bears” as our title tonight?

First, polar bears. Polar bears are a specialized branch of brown bears, diverging about 750,000 years ago. Their scientific name is Ursus maritimus, literally marine bears.  Unlike other bears they are almost completely carnivorous. Their claws are adapted for gripping their prey, and their heads and necks are longer and more slender, to enable them to pull a ringed seal out of its breathing hole. Polar bear fur is hollow and translucent, with no pigment in the fur itself. The fur traps air for insulation and directs the warmth of the sunlight down to the black skin beneath.They are excellent swimmers, routinely swimming over 10 miles. The record for a continuous polar bear swim is 400 miles. 

Unlike polar bears, which are land mammals that spend their lives in and around water, other marine mammals present more dramatic adaptations from their terrestrial cousins.  Seals, sea lions, and walruses are all pinnipeds.  Bears are their closest relatives and while the external appearances are quite different, the skulls show the similarity.  The common adaptations to their cold marine environments includes higher levels of hemoglobin and oxygen in their blood, a high tolerance for CO2 (to reduce the reflex to breathe frequently), and blubber. Blubber is not just fat, but has blood vessels and a complex structure to control the temperature of the creature. Polar bears, by contrast, are more recent adapter to the marine world; they have a lot of fat but not yet blubber. 

Walruses are extremely gregarious and live in a world dominated by touch. They rest in family groups that are so densely packed that it is hard to tell how many animals are in the group. Officially their collective noun is Huddle, but Cuddle actually seems even more appropriate. 

Pictured: a classic huddle with a large bull, an evening huddle on the shore, a pair of walruses on a small thin piece of ice, a drowsy walrus, swimming polar bear, comb jelly