Plankton Chronicles

The word "plankton" literally means "wanderer", and these floating wanderers of the ocean have a strange and alien beauty that has fascinated generations of biologists.

The Plankton Chronicles project uses modern microscopy and videography to make this world accessible to the average armchair explorer. They've produced a series of videos highlighting different planktonic organisms, using a technique called dark field optics, where objects are made visible by the light that they scatter, appearing light against a dark background.

The project is a collaboration between the Tara Oceans Expedition and the Oceanographical Observatory at Villefranche-sur-Mer.

One of the episodes, on planktonic protists (of course!), is embedded below:



I came by the site by way of this TED Talk by Tierney Thys:

How the 'brinicle' was filmed

If you haven't seen this video by now, you should watch it!



As sea ice freezes in the Antarctic, it leaves behind a concentrated brine which is trapped in channels within the ice. When this cold, dense brine, which is colder than the freezing point of water, seeps to the underside of the ice layer and sinks into the water beneath, it forms a sheath of frozen water around it, which eventually extends to the sea floor as a 'brinicle'.

For the BBC Nature series Frozen Planet, these brinicles were filmed for the very first time. The film's producer, Kathryn Jeffs, said that when she was preparing to film them, she couldn't find any information about them, even on the Internet.

Now, this video is among the most popular nature video clips online.

Jeff describes the technically demanding and physically difficult process of filming under thick ice in 2ºC water. As she put it, they were tremendously satisfied when they

... knew [they] had captured, for the first time ever, the creation of a rather sinister wonder of nature.

Björk and the Zombie Snails

No, it's not a tribute band. The quirky Icelandic musician Björk has a new album out, called Biophilia. Appropriately enough, the tracks are inspired by themes of nature and biology.

One of the songs in particular, "Virus", was written after Björk learned about "zombie snails" on YouTube. It has nothing to do with real viruses, though (Disclaimer: I haven't heard the album yet so I can't say if the music is any good). These snails are parasitized by a trematode worm called Leucochloridium paradoxum, which you can see in the photo below.

Snail infected with Leucochloridium paradoxum in its eyestalk.

Look closely at the eyestalk on the right. Yup, that's filled with worm. But it's not just one worm. It's a structure called the brood-sac, which contains hundreds of cercariae – little larval worms ("trematode life cycle" on Wikipedia. The sac is banded and green and pulsates. This attracts the attention of birds, which think that it's actually their favorite food, maggots or caterpillars. They swoop in and peck off an eyestalk with all the worms in them. The worms end up in the gut of the bird, and are carried in there to be pooped out somewhere else. Free transportation! Snails grazing along eat some bird poop with the parasites in them, and get infected, completing the cycle.

Find out more about the sneaky life cycle of this worm from this article on Wired magazine, or read the Wikipedia article, or just watch the video that inspired Björk:

Ray the Rotifer!

While gazing through the microscope at yet more pond water, I was surprised to see this swim past my field of view (click for larger versions)....

It is evidently some kind of rotifer (according to Maxine Mowe) with part of its cuticle expanded into lateral 'wings'. The animal is able to open and close these wings, and even flap them somewhat.

Do you think that there's some resemblance to the chaps below?

The resemblance may be misleading, though. The rotifer is about a quarter of a millimeter across, whereas these skates and rays can measure about a meter or more. The way that water behaves at microscopic scales is very different from the macroscopic scale that we (and these fishes) live in. For zooplankton, the dominant property of water is its viscosity, as opposed to its inertia. Where a manta ray would coast along for several meters after a flap of its mighty wings, this winged rotifer would instead come to an immediate halt. So what are those wings for, on the tiny rotifer? Looks like it's something for an enterprising student to find out.