Glaucus harvests the defenses of its prey and uses them against its own predators. We originally posted this episode at the New York Times, where you can read more.
Many organisms move with cilia. Most, like Stentor, are small. The ctenophores (also known as comb jellies) are an exception – they are the largest animals to use cilia for swimming. Ctenophore cilia refract light into beautiful pulses of color as they move. Sid Tamm recently published an excellent review of of ctenophore cilia (unfortunately the full text is only available to those with a journal subscription).
Filmed and edited by Stefan Siebert. Original music written and performed by Bryn Bliska. We originally posted this episode at the New York Times.
Shuyi Chiou’s animation explains the implications of the Central Limit Theorem. To learn more, please visit the original article where we presented this animation in the New York Times.
The song is Franz Danzi’s Wind Quintet Op 67 No 3 In E-Flat Major, 4 Allegretto, performed by the Soni Ventorum Wind Quintet. The narration is by Pathikrit Bhattacharyya. Further work by Ms. Chiou can be found at her site.
Alysse Austin, a student in Casey Dunn’s Invertebrate Zoology course at Brown University, describes sexual dimorphism in green spoonworm.
This is the first episode of CreatureCast to be distributed in partnership with the New York Times.
Special thanks to Rachel Kaplan and the Granoff Center for the Creative Arts. Music is “Sneeuwland” by Oskar Schuster.
An introduction to PhyloTree, a browser for the Tree of Life (or at least a very rough approximation of the Tree of Life) available at dunnlab.org/phylotree .
This video demonstrates some of the features of PhyloTree. It then shows the early explosive discovery of mammal species (most major mammal groups were discovered early on), and then shows the slow and steady discovery of cnidarians (many cnidarians remain to be described). The tool can also be used to quickly find the first species that was described in a group. The first siphonophore to be described, for example, was Physalia physalis (the Portuguese man o’ war).
Music is “Butterfly” by Delicate Steve (delicatesteve.com/).
Hiding from danger in the deep sea is a very different game than hiding from danger on land. In the sea, not only does a creature have nothing to hide behind, it can’t even camouflage itself, because it’s environment is just clear water. Perhaps not surprisingly, then, many animals of the sea have evolved ways of being transparent.
Here is a semi-interactive video (with the option of a single, non-interactive video here) from CreatureCast alum Sophia Tintori, featuring tips from a handful of ocean-dwellers that each have drastically different approaches to being invisible.
Score by Amil Byleckie, video made by Sophia Tintori, with a big thanks to Sönke Johnsen. Funding provided by Duke University Provost & Council for the Arts and the Office of Graduate Education at the University of North Carolina Chapel Hill. Released under a Creative Commons Attribution-Non Commercial-Share Alike license.
If you have ever been stung by a jellyfish or coral you’ve already encountered one of these – a nematocyst. It is the stinging capsule found within specialized cells of Cnidaria. Nematocysts have poison filled harpoons that rapidly fire to attach to and incapacitate prey, or to deter predators.
This 3D model, available for download at Thingiverse if you would like to print it yourself, is an homage to anatomical relief models that probably adorned your doctors office and junior high science classroom. It shows the nematocyst in three stages of discharge. First, the inverted harpoon is packed within the capsule. The harpoon is inside-out at this point. Second, a stimulus has led the capsule to pressurize, swinging open the operculum (the trap door at the top), and begin everting the poison filled thread. As it extends, it turns right-sideout, exposing hooked barbs as it goes. Third, the thread is fully extended. At this point, it would be lodged in the flesh of whatever brushed up against it.
This model was designed by Daniel Newman, a certificate student in the Natural Science Illustration program at the Rhode Island School of Design, while doing an internship facilitated by Amy Bartlet Wright in my lab. His original concept sketches can be viewed above, along with the printed models.
Thanks to Stefan Siebert and Bryn Bliska.
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.
Special thanks to Marjorie Thompson, Robert Sandler, and the Brown University Science Center.
The music is by Tony Higgins, aka junior85.