CreatureCast- Jellyfish Theater

posted by Sophia Tintori / on July 16th, 2010 / in Arthropods, Jellies, Parasites, Podcast, Symbiosis

In the vast ocean, without walls and far from the floor,  jellyfish can become drifting islands of activity. Creatures from far and wide will congregate on them to act out the ups and downs of life and death. Jellyfish have symbiotic relationships with living things of all sizes, from fish and shrimp that feed off them or off the pieces of food left between their tentacles, to single-celled photosynthesizing organisms that take shelter inside the cytoplasm of the jellyfish’s cells.

In this video, Trisha Towanda talks about one particular jellyfish, the fried egg jelly, and some of the other creatures that hang around it. There are moon jellies that the fried egg jelly eats. These moon jellies have little parasitic crustaceans on them called amphipods, which jump to the fried egg jelly while the moon jelly is being eaten. There are also crabs that ride around on the fried egg jelly, that are parasitic in their youth, but then grow to be helpful symbionts by eating off the little amphipods. This sort of coming of age story, where a symbiont’s relationship changes over its lifespan is an unusual one. Trisha put the pieces together by staring at them for hours and days and weeks when she was in Erik Thuessen‘s lab at Evergreen State College.

Many thanks to Trisha Towanda, who is now stationed in the Seibel lab at the University of Rhode Island. This video was edited and animated by Sophia Tintori, with an original score by local pop hero Amil Byleckie. It is released under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license. Here is the paper Trisha wrote about the story.

Axolotls and the French Intervention

posted by Sophia Tintori / on July 15th, 2010 / in Uncategorized

Léon-Eugène Méhédin was a photo-journalist in the mid 1800s. After documenting the Crimean War, the Italian Campaign of Napoleon III, and taking pictures in Egypt and Nubia for a photographic encyclopedia, he traveled to Mexico with the French Expeditionary Forces. There he claims to have discovered the ruins of Xochicalco. He took papier machê molds and many photographs, all of which were reported to have been too artistic to be of any scientific value, and have never been seen since. Upon their return from Mexico, the French Expeditionary Forces brought 34 funny mexican salamander-like animals back to give to the Natural History Museum of Paris.

These animals, called axolotls, were first seen as a scientific oddity; they spend their whole lives looking like the larval state of a salamander, but they become sexually mature and can reproduce without metamorphosing into the adult form. In 1863, Méhédin gave 6 of these animals (and then one more, a few years later) to a local biologist named August Duméril, who started breeding them and enthusiastically sharing thousands of them with his colleagues all over Europe.

Since then axolotls have become one of developmental biology‘s model organisms, mostly because they are easy to raise, their embryos are large and transparent, and axolotls can regenerate their limbs and heart. In that same time, the original populations of wild axolotls, which live solely in the lakes in and near Mexico City, have dwindled to the point of near-extinction.  The vast majority of axolotls alive today are being bred in developmental biology labs across the globe. Most individuals can be traced back to two of those 7 axolotls from Méhédin in the 1860s.

Above is a video of a some axolotls captured by Stefan Siebert, a post-doc in the Dunn lab. It was edited by Sophia Tintori, and is released under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license. Thanks to Dr. Nadine Piekarski for telling us about their ancestry.

More Budding Jelly Babies

posted by Sophia Tintori / on July 1st, 2010 / in Development, Jellies, lab, lifecycles

We found more jellyfish being born in our lab this week!

Rebecca Helm, a Dunn lab graduate student, left a couple of bowls of salt water and hydroids out on the table overnight, instead of the refrigerator where they usually live at around 50 or 60 degrees fahrenheit. The next day she came in and found them doing this:

This particular animal is called Podocoryna carnea. Like most jellies and close relatives of jellies, it has a pretty elaborate life cycle. This one involves a free swimming jellyfish, and a larva that swims around then lands on the back of a hermit crab’s shell. Then the larva metamorphoses into a polyp, which buds more polyps, growing into a whole colony on the crab’s back. The colony is made up of lots of polyps that are all connected and share fluid through a web of tubes that circulate partially digested food. Some members of this colony will eventually bud new swimming jellyfish.

The video at the top is of one of the colonies we have growing in our lab. These polyps were given to us by friends, but they can also be collected from hermit crabs at the beach, then grafted onto slides. They seem to grow well on slides, and slides are much easier to take care of then crabs.

Some of the polyps in the video have pink balls growing around the top. These are the buds that will mature to become free-swimming jellyfish. If you look closely, you can see jellies of all stages of maturity growing, including some that are ready to break free. After they swim off they will continue growing. We’ll try to follow up on how that goes.

Video by Sophia Tintori, life cycle drawing by Perrin Ireland, both released under a Creative Commons Attribution-Noncommercial-Share Alike license. Thanks to Diane Bridge and Neil Blackstone for the Podocoryna colonies. Check out this earlier post of the other polyps we saw budding jellyfish in our lab.