It’s not every month that I can showcase a recently-discovered species in this column. But February's featured organism is so hot-off-the-presses that had I been writing this article around this time last year, it would not have even been an option. The species effectively did not exist back then, despite having been observed decades prior.
Between 1999 and 2000, biologists noticed a copious quantity of large pink jellyfish in the Gulf of Mexico. Back then, the animals were presumed to be an occurrence of the already known Mediterranean species Drymonema dalmatimum. Nevertheless, they decided to take some of them back to the lab for closer inspection. Now, after 10 years of messy dissections and DNA analysis, researchers at the Dauphin Island Sea Lab have determined the jellies to be an entirely new species; Drymonema larsoni. Dubbed the “pink meanie” the marine creature made its official debut on the cover of the latest issue of The Biological Bulletin and is described in an article by Keith Bayha and Michael Dawson.
Part of what makes Drymonema larsoni worthy of the coveted cover photo is that this new species was different enough to cause the authors to name a new family – Drymonematidae – to host it, a taxonomical revision the likes of which the world of jellyfish has not seen since 1921. In case you’ve forgotten your taxonomy pneumonics, here’s the one I learned to help keep the order (pardon the pun) straight: King Phillip Came Over From Germany Saturday.* That translates into KPCOFGS, which represents Kingdom, Phylum, Class, Order, Family, Genus, Species. Standard binomial nomenclature labels an organism using just the genus and species names. At 3 names in, you can see why a family-level revision is potentially a bigger deal than just a new species.
A Few Words About Jellyfish in General…
Jellies are far less compartmentalized than our own species. Theirs is a minimalist lifestyle. They have no brain, no skeleton and they lack a specialized digestive system. The bell-shaped umbrella that characterizes jellyfish gets its structure from a gelatinous substance called mesoglea. Food enters and waste exists through the same gastrovascular cavity. Unlike true fish, jellies lack gills and oxygen instead diffuses through their thin skin. Having radial symmetry, they don’t even have a right and left side, just a top and bottom, from which long tentacles often dangle.
…and Pink Meanies in Particular
So far, written information about D. larsoni is scant. The Biological Bulletin article contains a great deal of detail regarding morphology†, but less on behavior or anything else you might understand without getting a PhD in marine biology. However, the few news blurbs I encountered were all quick to mention that pink meanies eat other jellyfish, specifically moon jellyfish. They’ve been observed impressively attacking jellies much larger than themselves. The pink meanies accomplish this by grasping the prey with their tentacles and digesting it using proteases secreted from tentacle-like features called “oral arms”. Tentacle number varies proportionally to the size of the bell (192 on average), but most of the D. larsoni specimens were found to have 4 oral arms. Other jellyfish, which often feed on plankton, digest their food using gastric filaments that line their gastrovascular cavities. These filaments were absent in D. larsoni, a loss that the authors attributed to the organism’s tendency to specialize in consuming other jellyfish.
The Name of the Rose
|what it actually looks like|
* There are ample variations of this pneumonic – Kids Prefer Cheese Over Fried Green Spinach, for instance – some of which I can’t repeat here for reasons of decency.
† Velar lappets per octant, axial position of rhopalia, stotocyst length and width, etc. You can probably guess why I’m opting not to focus on such things.