We have a front and a back and two legs. We walk around on our two legs. When we need to change the direction we are moving in, we first turn our body to face the new direction and then use our same two legs to keep going. It works for us.

But what about a round animal that also has an odd number of limbs? This is the question that Henry Astley, a graduate student in Tom Robert’s lab here at the Brown University Department of Ecology and Evolutionary Biology, set out to answer. Like their relatives the starfish, brittlestars have five arms. Unlike starfish, which crawl around with the thousands of sticky tube feet that line the bottoms of their arms, brittlestars get around by moving their whole arms. They can move much more quickly than starfish, scurrying under a rock or sprinting across the ocean bottom.

Surprisingly, nobody had previously described the details of how brittlestars get around with their arms. Do all five arms play an equal part all the time, or do only some of the arms move at once? Do they have a favorite front and back, or can any arm serve as the front or back?

In his paper published this week (“Getting around when you’re round: quantitative analysis of the locomotion of the blunt-spined brittle star, Ophiocoma echinata“), Henry answers all these questions. It turns out that most of the work of getting around is only done by two arms at a time. These arms move in a rowing motion, much like a sea turtle crawling along the beach, while the other arms stay out of the way. My favorite part of the story though, is how brittlestars turn. Rather than rotate their body to face a new direction, as we do, they just chose a new front and back and row with a different pair of arms. Not only do they not have a favorite front and back, they constantly change their front and back to change direction.

Eliza Cohen, from Erika Edwards’ Plant Diversity course at Brown University (Biol 0430), talks about the history of ginkos.

Music by bitbasic. The animations were photographed at the Brown University Science Center. Thanks also to the Granoff Center for the Creative Arts.

Arisa Lohmeier, from Erika Edwards’ Plant Diversity course at Brown University (Biol 0430), describes our co-dependent relationship with corn.

Pathikrit Bhattacharyya (aka Po), from Casey Dunn’s Invertebrate Zoology (Biol 0410) course at Brown University, tells the story of how the lancet liver fluke gets through life.

The hand-drawn animations were photographed at the Brown University Science Center. Thanks also to the Granoff Center for the Creative Arts.

The songs Staccato and Spooky are by Alastair Cameron.

Karen Connolly, from Casey Dunn’s Invertebrate Zoology (Biol 0410) course at Brown University, tells the story of how echinoderms (starfish, sea urchins, and their relatives) can change the stiffness of their skin at will.

Music by Scott Joplin.

Stephanie Yin, from Casey Dunn’s Invertebrate Zoology (Biol 0410) course at Brown University, tells the story of a parasitic barnacle with a fascinating lifecycle.

The hand-drawn animations were photographed at the Brown University Science Center. Thanks also to the Granoff Center for the Creative Arts.

Music by King Vitamin, Lino del Vecchio, and Val.

Amber Harris, from Casey Dunn’s Invertebrate Zoology (Biol 0410) course at Brown University, tells the story of jumping spider courtship.

For more information on the mating rituals of jumping spiders visit the Elias Lab.

The hand-drawn animations were photographed at the Brown University Science Center. Thanks also to the Granoff Center for the Creative Arts. Music by scottaltham and Weston Wyse.

We are pleased to present our first pamphlet – an illustrated guide to the lifecyles of some fascinating organisms. These lifecycles were selected and illustrated by Manvir Singh, a student in Casey Dunn’s Invertebrate Zoology course at Brown. Manvir is also the author of The Evolutionist’s Doodlebook.

Lifecycles is released under a creative commons license, and available for download at archive.org. If you’re interested in purchasing a printed tabloid version of this pamphlet (11.25″ by 15″), contact manvir_singh@brown.edu.

Lara Crystal, from Casey Dunn’s Invertebrate Zoology (Biol 0410) course at Brown University, tells the story of how anglerfish find, and keep, a mate.

The hand-drawn animations were photographed at the Brown University Science Center. Audio was recorded at the Granoff Center for the Creative Arts. Music used by permission of North America.

Katherine Hadley and Jonathan Leibovic, from Casey Dunn’s Invertebrate Zoology (Biol 0410) course at Brown University, sing a song about tardigrades. They composed the song, performed it with friends, and made the animation.

The hand-drawn animations were photographed at the Brown University Science Center (http://brown.edu/academics/science-center/). This video is released under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license.