How do krill grow?

posted by Lisa Roberts / on June 4th, 2010 / in Arthropods, Development, lifecycles, Podcast, Science & Art

Early last year, at the Australian Antarctic Division (AAD), I saw an unusual sight: the birth of a live Antarctic krill, Euphausia superba.
The newborn appeared on a video screen that projected the view of a camera poised over a petri dish. A tremulous form emerged from its egg with its legs beating furiously!
This event began a continuing conversation with krill research leader, So Kawaguchi.
Back in my Sydney studio, I worked with So’s words and images. He explained (by email) how krill grow, and sent me diagrams by John Kirkwood to work with. I also found data sets online of how krill appendages move (Uwe Kils). Piano music was improvised by an 11 year old friend, Sophie Green.
This is the first of some animations that I am making to more fully describe this elusive and most important creature.
Krill are central to the marine life food web. Their health is endangered as a result of oceans becoming more acidic (as carbon increasingly enters the atmosphere and then dissolves into the water).
A new research project at the AAD is to record changes in normal krill development in increasingly acid water. Next month (June 2010) I return to the AAD krill nursery to find out more about this research.
I will also record So Kawaguchi describe what he has identified as a circling krill mating dance. What a fine gesture of continuity!

This video is released by Lisa Roberts under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license. More animations can be found at AntarcticAnimation.com.

CreatureCast – Individuality

posted by Sophia Tintori / on April 8th, 2010 / in Development, Jellies, Podcast, Siphonophores

Last month we posted a video of a siphonophore (one of the Dunn lab’s favorite animals) swimming freely in the ocean. In this next installment of CreatureCast, Casey Dunn describes how siphonophores help us question what we think of as an individual.

There are different ways to think of individuality. Individuality can refer to function- whether an organism operates and interacts with the world as a unit. A fish is a functional individual, but so is an ant colony. Individuality can refer to evolutionary descent. In this respect our liver is not an individual, there was no ancestral free-living livers out there that our liver is descended from. But our mitochondria are individuals in this sense. They evolved from free-living bacteria that became incorporated into other cells. Individuality can also refer to the process of evolution. In this sense an individual is any entity that has the properties necessary for evolution by natural selection- it reproduces and has variable heritable properties that influence the chances of survival. This could be a free living cell, a cell in a body, an entire multicellular organism, and even groups of organisms in some cases.

All of these definitions of individuality are in alignment in most of the organisms we are familiar with. A bird, a rose bush, and a fly are all individuals as functional entities, according to their ancestry, and as units of selection. This makes it easy to get lulled into thinking of individuality as a monolithic property.

A siphonophore colony is a functional individual. But a siphonophore colony is made up of many parts that are each equivalent to free living organisms such as sea anemones and “true” jellyfish. So by the evolutionary descent definition it is a collection of individuals. The colony as a whole is acted upon by natural selection, making it an individual in the sense of the process of evolution. But it is entirely unclear whether natural selection can act on the parts within the colony, as it does on our own cells when we get cancer, since we don’t know about the heritability between the parts of the colony.

Siphonophores, by forcing us to disentangle what we mean when we call something an individual, help us understand the evolutionary origins of individuality. These different aspects of individuality don’t necessarily evolve at the same time, and one or more of them can even be lost. Organisms like siphonophores provide glimpses of these different combinations of individuality.

Most of the stills are plates from the first papers describing siphonophores. They were published from the mid 1800’s to the early 1900’s by Henry Bryant Bigelow, Ernst Haeckel, and Karl Vogt.

The song New Homes is by Lucky Dragons, the siphonophore video is from Dr. Steve Haddock at MBARI, the podcast was produced by Sophia Tintori, and the video is published under a Creative Commons Attribution Non-Commercial Share Alike 3.0 license.

CreatureCast – Diving for Jellies

posted by Sophia Tintori / on March 3rd, 2010 / in History, Jellies, Podcast, Siphonophores

Here in the Dunn lab, siphonophores are our favorite animal and the focus of much of our research.

Dr. Phil Pugh is a good friend of the lab, and he also happens to have described more new species of siphonophores than anyone who has ever lived. In the video below, he describes what it’s like to come across a siphonophore in the deep sea with a submarine. What looks like one long body in this video is actually a free-swimming colony of clones — many genetically identical bodies that are all attached. But each body in the group isn’t just like its neighbor. They each do a specific job for the colony. Some individuals will swim, some will catch food, and some will reproduce.

More on siphonophore biology can be found in papers here and here. But we’ll talk about all that later — for now, just take a look.

Footage courtesy of the Bioluminescence lab at the Monterey Bay Aquarium Research Institute. Music graciously provided by Raf Spielman of The Golden Hours. Edited by Sophia Tintori. This podcast is published under a Creative Commons Attribution Non-Commercial No Derivatives 3.0 license.

CreatureCast – Picky Females

posted by Sophia Tintori / on January 14th, 2010 / in lifecycles, Podcast

A couple of weeks ago the Dunn lab went out after work, and we got to talking. There’s this thing that usually happens whenever we get together after a day in the lab or field– being a group where everyone focuses in one way or another on the diversity and evolution of reproduction and development, we start to tell stories about how animals reproduce. Someone mentions some surprising tidbit of reproductive biology they recently heard, and that sets it off. Then someone else remembers a weirder story, and tells it. This spurs someone else’s memory, and so on, and then I start feeling overwhelmed.

Well, this time we got caught up on the issue of female choosiness. It takes more energy and resources to make an egg packed with resources, or to raise offspring, or to carry a baby inside the womb, than it does to make sperm. This often leads females to be more selective about their mates than males are. We started talking about ways in which female choosiness manifests itself; sometimes through behavior, sometime through anatomy, and sometimes at the level of the cell. And then sometimes it is all for naught.

In this episode of CreatureCast Rebecca Helm, a graduate student in the Dunn Lab, recounts a few short stories about the many levels of reproductive selection.

Editing and animation by Sophia Tintori. We Want To Be Old by Bird Names. Photos of bowers by Mila Zinkova and Peter Halasz. Duck story from the research of Richard Prum and Patricia Brennan. Video of the inside of a comb jelly egg by Christian Sardet, Danielle Carré and Christian Rouviere, from the BioMarCell group. This video is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

CreatureCast – Multicellularity

posted by Casey Dunn / on October 14th, 2009 / in Podcast

In Episode 2 of CreatureCast, Sophia Tintori and Cassandra Extavour talk about the evolution and development of multicellular organisms, and in particular the specialization of reproductive cells. Audio production and animations are by Sophia, who normally studies siphonophores in the Dunn lab. Music by Cryptacize.

With Episode 2, we are also happy to announce that you can now subscribe to the CreatureCast video podcast through Brown University at  iTunes U.

Creative Commons License
This video is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

CreatureCast – Squid Iridescence

posted by Casey Dunn / on August 12th, 2009 / in molluscs, Podcast, Science & Art

We are pleased to present Episode 1 of CreatureCast, by Sophia Tintori. In this first video, Alison Sweeney talks about work that has been done in the Morse lab on Squid iridescence. Audio production and animations are by Sophia, who normally studies siphonophores in the Dunn lab. Music by  Lucky Dragons (here, and slowed down versions of this and this) and Sophia on the musical saw.

Creative Commons License
This video is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

(Episode 1 was replaced with a new slightly different cut on August 18, 2009. It is now higher resolution and includes a couple different musical tracks.)

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