On July 21st the Beagle was nearing its next destination in Uruguay. And, for possibly the first time, Darwin encountered penguins – very loud penguins. He writes:
“The weather to day felt just like an Autumnal day in England.— In the evening the wind freshened & a thick fog came on.— These are very frequent in the neighbourhead of the Plata, & we are only now about 50 miles from the Mouth.— The night was dirty & squally: we were surrounded by Penguins & Seals which made such odd noises that in the middle watch Mr Chaffers went below to report to Mr Wickham that he heard cattle lowing on shore.” (July 21)
Of the 17 species of penguins in the world, there are currently 3 species that can be found in Uruguay – the King Penguin (Aptenodytes patagonicus), the Rockhopper Penguin (Eudyptes chrysocome), and the Magellanic Penguin (Spheniscus magellanicus). The first type is a rare occurrence in Uruguay, and so I suspect (unless there range has changed in the last 200 years) that it was one of the later species that Darwin encountered. If I had to put money on it, based on range and sheer numbers, I’d bet it was Magellanic Penguins.
Magellanic Penguins (from Wikipedia Commons):
I’m sure this is not the last time Darwin will cross paths with penguins so for today, let me introduce these flightless birds with some general information (and hopefully come back to them in some more detail later).
Penguins belong to the order Sphenisciforms and the family Spheniscidae. They are a family of birds that have “traded” (in an evolutionary sense) their ability to fly for adaptations (such as streamlined bodies, flippers, and fat) that make them great cold-water swimming birds. Why can’t they do both? Well, everything takes energy. Flight takes a lot of energy and requires different adaptations than life in the water (where penguins typically spend half their lives). Taking resources away from the flippers, would decrease the penguins survival chances. So in the end, the flight just has to go.
Rockhopper Penguin – there is some debate as to whether or not there are several species of rockhoppers, or if they are all subspecies. You may remember these guys from the movie Happy Feet (along with the Emperor Penguins, therse where the other “main characters”). (Image from Wikipedia Commons.)
Ultimately, penguins are perfectly adapted to their environment – they don’t need flight to get to their food source (fish, krill and squid) and they nest on the ground (there are not many trees in many of the places penguins live). So flight would really be a luxury anyway.
These adaptations to the sea go back quite a ways. The earliest fossil penguins have been found in rocks about 60-70 million years old. I think I’ll save this story for a later post – it deserves more then a passing mention :).
Waimanu manneringi – a reconstruction of the earliest known penguin ancestor. Notice that it still has wings, though it is believed that it had already lost its ability to fly. (From Wikipedia Commons.)
Penguins have another classic adaptation – counter shading. Their black and white color is a form of camouflage. A predator looking down on a swimming penguin would see its “dark” back side, which blends in with the surround ocean. A predator from below would see its “white” front side, which blends in with the sky above. (To read about gastropods that have counter shading see Purple Snails and Blue Slugs.)
Contrary to common misconception, penguins are a southern hemisphere species (with just a tiny dip into the northern hemisphere around the Galapagos Islands). Polar bears and penguins are NEVER found together.
If you want to hear what Darwin heard today, check out this great collection of penguin sounds from Soundbard.com. Scroll down and you can listen to different species.
That being said, the “cattle-like” sound the sailors heard was probably from the seals. More on those guys another day. (RJV)