Riley Thompson made this animation about the fascinating lifecycle of narco babies.
We usually don’t think of babies that grow inside their mothers as parasites, but sometimes the lines get very blurry. This is especially true in Narcomedusae, a group of poorly known jellyfish found throughout the world’s oceans. Some species of Narcomedusae (affectionately called narcos by the people that study them) can grow inside their own mother, who provides nourishment and a safe environment for her. The narco babies can then leave their mother, find another jellyfish of an entirely different species, attach to its flesh, and thrive on the nourishment and safe environment it provides. The physiological interaction of baby and host is similar in both cases – the host provides, the baby takes. But in one case the host is providing for its own offspring, in the other it is providing for somebody else’s offspring.
Thanks to Rebecca Helm and Fabien Lombard for their help translating the wonderful paper on narco life cycles: Bouillon, J. (1987) Considérations sur le developpement des Narcomeduses et sur leur position phylogénétique. Indo-Malayan Zoology 4 : 189-278.
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.
Here is a little plant that starts it’s life high up in the tree tops, where it can find more light than the dark understory of the rainforest. As it grows though, soon getting enough water becomes limiting factor, and the plant will drop a shoot to the ground.
Matt Ogburn, a graduate student in Erika Edwards’ lab at Brown University, describes this little plant, the strangler fig, and explains how it eventually grows to take over the whole host tree and strangle it to death.
Symbion pandora is a microscopic animal that lives exclusively on the mouth-parts of lobsters. When we think of a life-cycle, we usually think of a baby growing into an adult, a female mating with a male, and then the female giving birth to a baby. But as Symbion pandora demonstrates, this isn’t always the case. Symbion pandora undergoes both asexual and sexual reproduction. Its life cycle is especially interesting because the timing of its sexual reproduction matches the moulting of its lobster host. This allows Symbion pandora to move from the lobster’s old shell to its new one, a remarkable solution to the problem of a temporary home. First described in 1995 by Peter Funch and Reinhardt Kristensen, Symbion pandora’s life-cycle provides insight on the incredible diversity and range in the ways organisms grow and reproduce.
This is a really nice video that was published in the Journal of Plankton Research this past February, as a part of this article about krill.
Even though krill make up a large fraction of the living mass of the ocean (and are also the food for large charismatic sea mammals), many aspects of their biology is unknown, including the way they reproduce. Recently Dr. Kawaguchi and his colleagues filmed the process happening near the sea floor, which was surprising because krill are notorious for living their lives swimming around up higher in the water, far from the floor.
The footage that the researchers collected was a bit chaotic (above, left), and so they gave it to Lisa Roberts, an animator (and CreatureCast contributor), to illustrate the process. She traced the motions of the crustaceans from the videos, and also practiced the moves with some shrimp from the market (above, right).
The original video footage from the deep sea is also really nice to watch, and can be found here, at the Journal of Plankton Research website.
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.
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!