Kodiak Daily Mirror - Nasal drift an important part of whale evolution
Nasal drift an important part of whale evolution
by Switgard Duesterloh
Jun 20, 2014 | 63 views | 0 0 comments | 45 45 recommendations | email to a friend | print
Many people, including myself, are mesmerized and fascinated by the sight of marine mammals. The behavior of the sea lions on their “home dock” in the Kodiak harbor seems almost human when they are lazily lounging in the sun, barking indignantly at the youngsters that jump wet and cold out of the water to crawl across their sunwarmed bodies in search of a good place to snuggle. Similarly the sea otter, when he floats on his back grooming his fur, staring at the visitors as if they had just interrupted his private bath time. Or watching a group of seals with their round heads, big eyes and cute whiskers bobbing at the surface to get a better look at us only to dive and quickly dart away a moment later.

While pinnipeds, as the family of seals and sea lions is called, fascinate by their behavior and features, the sight of whales fills me with a sense of awe. There is a certain element of surprise every time an animal stops its daily business and approaches for any kind of interaction, but with an animal as huge as a school bus, the encounter leaves me with a sense of priviledge that something so great would grace me with its presence.

Nonetheless, while I have seen many whales in their natural environment, it is rare to see their face. The reason they don’t often bother sticking their heads above water is the nasal drift. The nasal drift is the process by which in the evolutionary development of whales the nose wandered from the tip of the snout to the top of the head. The blowhole is really the whale’s nose. Toothed whales have a single blowhole, while all the baleen whales have a paired blowhole.

According to Wikipedia, all extinct animals that are thought to have been ancestors of modern whales — all the way back to a prehistoric mammal with hooves that lived and hunted on land much like today’s wolfs —had noses at the tip of their snouts. Adapting to a wet environment, whales perfected and diversified their body plans over millions of years. It has always puzzled me how the original carnivorous predator has then diversified into the toothed whales and how the baleen was developed. Apparently, baleen developed from teeth. There once existed a whale that had teeth, but in its fossilized skull were some telltale structures that in modern baleen whales supply the baleen with nourishment.

Evolutionists in their quest to unravel the procession of species are often helped by a curious phenomenon in the development of embryos. Often, the changes that have happened to a species through the course of evolution are mimicked in the development of the embryo. For example, the human fetus goes through a stage where it is entirely covered with hair. The younger whale fetus has a nose at the tip of its snout, which in the course of development makes its way up the head until it is located over the eyes.

What is the advantage of the nasal drift? Unlike a seal, that has to change its body direction from vertically standing in the water to give us that curious look to a horizontal position when it darts away, the whale does not even need to lift its head. Considering the size of the whale it would be very impractical to move the whole body back and forth from a vertical to horizontal position every time the animal wants to take a breath. In addition, while the seal is looking at something above the surface, it can no longer watch for danger approaching from below. This which may be one reason seals appear a little twitchy and nervous. The big whale has developed in a world where there were no predators outside the ocean capable of attacking it, so its focus was better kept under water even when it was at the surface breathing. Imagine a whale mother with a young calf that is persued by sharks or orca whales: she better keep her eyes peeled under water while making sure her little one is close to the surface so it doesn’t drown.

When humans venture into the water, the urge to see and the need to breathe has led them to the invention of a dive mask, fins and a snorkel. The fins mimick the fins and flippers of fish and marine mammals, while the snorkel is a blowhole at the top of the head, allowing us to keep our eyes under water while breathing at the surface. So, when you put on a snorkel you are short-cutting millions of years of evolution of the nasal drift. The ability of humans to design inventions that replace specific evolutionary adaptations places us in a position where other species can not adapt to the changes we introduce to their world. Our ability to hunt a huge whale from above has almost led to the extinction of numerous species of whales. Our unique ability to dominate other species through the invention of special tools gives us an ethical responsibility to ensure their survival. Because whether we believe in evolution or in creation, diversity of species is what makes our planet the amazing, breathtaking, and life-giving place it is.

Switgard Duesterloh Ph.D., is an assistant professor of natural sciences at Kodiak College. She operates the Kodiak Ocean Science Discovery Lab and teaches ocean science to students throughout the Kodiak Island Borough School District.

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