Among the differences that I’ve noticed during my second trip to Antarctica is the abundance of animal life in and around McMurdo Sound this late in the austral summer. Over the course of the week I’ve seen many hundreds of Adélie and emperor penguins, dozens of Weddell and leopard seals, Antarctic skuas, and a surprisingly large number of whales including minkes, orcas, and fins.

I am tempted to talk at length about biodiversity in Antarctica, a topic that fascinates me. Instead, though, I think I’ll just share a few pictures of what I actually saw in the McMurdo environs. Unfortunately, I’m not a quick-draw professional with my camera, and most of the animals I encountered had no patience for posing. So I missed the most fleeting and dramatic encounters, and the photos I did get are definitely not National Geographic quality. Sorry.

I stumbled across this Weddell seal napping along the shore of Cape Evans.

He roused himself to examine Mike and me for a moment.

And then he went back to his nap.

On a helicopter tour around the edge of the ice we saw dozens of whales below us, including these extra large ones. I couldn't see clearly enough to identify them, but our guide said they were sperm whales.

We saw orcas and minkes in openings in the ice around McMurdo Station and Scott Base. I actually saw a couple of orcas breach at close range. Here is one of a pair of minkes that I watched for an hour one day.

I could never quite get a clear picture of his head when he surfaced.

I concluded that he was a minke because of the shape of his dorsal fin.

Outside of the rookeries I saw groups of Adélie penguins here and there along the sea edge as I hiked.

This curious fellow approached me near the Terra Nova Hut at Cape Evans.

Skuas eat penguin eggs and chicks. We saw several skuas dive-bombing the Adélie rookery at Cape Royds.

Skuas eat penguin eggs and chicks. We saw several skuas dive-bombing the Adélie rookery at Cape Royds.

Leopard seals also prey on penguins. The big guy at the center of this photo didn't look like a leopard seal to me, but he steadily moved toward the Adélies, and they kept skurrying away from him.

Of course, there were Emperor penguins in abundance.

Of course, there were Emperor penguins in abundance.

OK, now for a few informational notes. Recent studies indicate that there are more the 1,200 animal species in Antarctica. They range from microscopic mites to huge blue whales, which are believed to be the largest animals ever to have lived on Earth. Most of the species are marine. There are very few purely terrestrial species on the continent. A flightless midge measuring 1/4 inch (6.35 mm) long is the largest of those terrestrial animals.

There is great marine biodiversity, relying in large part on phytoplankton. The phytoplankton are consumed by krill, tiny shrimp-like crustaceans which form the base of the food chain for squid, fish, seabirds, seals, and whales. I saw huge masses of krill when I descended into an observation pipe through the ice during my last visit.

At this point in the season the sea ice around McMurdo is too thin to support the observation pipe. It will be reinstalled once the ice thickens over the winter.

At this point in the season the sea ice around McMurdo is too thin to support the observation pipe. It will be reinstalled once the ice thickens over the winter.

The bottom line is that the Ross Sea is a unique and largely intact marine ecosystem with a robust food web and abundant predators. It is a glory to behold, and it has fascinated and awed humans since the arrival of the first explorers.

It is also, though, a very fragile ecosystem facing serious long-term challenges such as anthropogenic climate change and encroachment of invasive species, as well as more immediate threats such as the introduction and expansion of commercial harvesting of fish.

However bothersome or inconvenient self-restraint may be at times, we cannot in good conscience avert our eyes from these challenges. Only man can protect the Ross Sea from man.