"The earliest sawfishes likely arose in the shallow Tethys Sea, that ocean surrounded by the ancient continents of Godwanda and Laurasia, during the Cretaceous period at least 60 million years ago," writes Dr. M. at Deep Sea News.
These "sole survivors of an ancient bloodline" now number only seven species which roam the muddy bottoms of coastal areas, bays and estuaries.
All sawfishes can move easily between fresh and saltwater and often venture deep upstream into rivers. The sawfish lifestyle puts this both their size and saw near humans. All seven species are considered critically endangered by the IUCN. As much as we have impacted them, sawfish have also greatly influenced our culture.
And now, they're one of the most threatened species on our planet. Thanks, humans!
This is a behavior rarely caught on camera, and is the result of three live cams set up by explore.org, Polar Bears International, Parks Canada, and Frontiers North Adventure to capture the annual polar bear migration this year (the point being to get people to think more about how climate change is impacting the north, and inspire an annual event similar to Earth Day (or Groundhog Day).
Ed Yong writes about the Chinese soft-shelled turtle: "Looks like someone glued the snout of a pig onto the face of a fish, with the texture of a scrotum for good measure. But its bizarre appearance pales in comparison to an even more bizarre, and newly discovered, habit: it urinates through its mouth."
From a public perspective, biology in the oceans, like biology on the land, tends to favor the charismatic megafauna. Stop by your local aquarium and you’ll find masses huddled around the seal pool or the shark tank.
Sometimes, I get so jealous of British television. Apparently, there's a whole series over there called Inside Nature's Giants. It's basically a zoology dissection show, where scientists break down large, exotic animals in ways that help teach viewers about evolution, biology, and the science of animal locomotion.
John Hutchinson is an American zoologist who works as a professor of evolutionary biomechanics in the UK. He's one of the scientists who works behind the scenes on Inside Nature's Giants. He also blogs at What's in John's Freezer?. It's a great title and it gets right to the point: Hutchinson has a job that is centered around the frozen carcasses of all manner of strange (and usually rather large) creatures. His research is all about the evolution and mechanics of motion. He studies living animals, both through dissection and 3D modeling, and he tries to use that data to better understand how extinct animals—including dinosaurs—might have moved around.
It's fascinating stuff. And the photos are nigh-on mind blowing. Right now, at John Hutchinson's blog, you can see a collection of shots from dissections and CT scans done for Inside Nature's Giants—including the dissection of an elephant.
Because I know that some of you are delicate and it is almost lunchtime, I've opted to not post my favorite photo from that dissection on the main page. But you should check it out below the cut.
Here's a diagram that shows the relative size of a great grey owl's body to its feathers. It's hosted on Wikimedia commons, labelled "Cross sectioned taxidermied Great Grey Owl, Strix nebulosa, showing the extent of the body plumage, Zoological Museum, Copenhagen."
I dig this because, on verbal description, this sounds rather dull. X-rays of fishes. Great. But when you actually see the images you remember two very important facts: First, fishes have tons of little, teeny bones packed into a relatively small body; Second, fishes come in a wide variety of frequently crazy shapes. That all adds up to fish x-rays being way more interesting than you might initially guess.
U xpect adorabulness. U gets it. But kittehs also gives u edukashun n' sientific nuance.
That's all the LOLcat speak I can muster in one go. Seriously, watch this video from Big Cat Rescue. It's fascinating. And, you should know, at the end, they link you to a slightly less educational feature about ocelots and lynx chasing laser pointers. Just sayin'.
Young loggerhead turtles, for example, read the Earth's magnetic field to adjust the direction in which they swim. They seem to hatch with a set of directions, which, with the help of their magnetic sense, ensures that they always stay in warm waters during their first migration around the rim of the North Atlantic. Over time they build a more detailed magnetic map by learning to recognise variations in the strength and direction of the field lines, which are angled more steeply towards the poles and flatter at the magnetic equator.
What isn't known, however, is how they sense magnetism. Part of the problem is that magnetic fields can pass through biological tissues without being altered, so the sensors could, in theory, be located in any part of the body. What's more, the detection might not need specialised structures at all, but may instead be based on a series of chemical reactions.
Even so, many researchers think that magnetic receptors probably exist in the head of turtles and perhaps other animals. These might be based on crystals of magnetite, which align with the Earth's magnetic field and could pull on some kind of stretch receptor or hair-like cell as it changes polarity. The mineral has already been found in some bacteria, and in the noses of fish like salmon and rainbow trout, which also seem to track the Earth's magnetic field as they migrate.