|Ophiuroids on Jelly in Mozambique. Photo by Andrea Marshall, Daily Mail, http://www.dailymail.co.uk/~/article-3990782/index.html#i-570251ad33a88841|
1. How many different types of Jellyfish species does Ophiocnemis marmorata occur ON??
The paper reports at least five or six, including at least 3 species of Rhopilema, Cephea cephea (the cauliflower jellyfish), Netrostoma and Aurelia aurita. But other internet records and social media show further hosts.. such as this hydrozoan, Aequorea from Thailand..
|From Chaloklum Diving in Singapore, http://www.chaloklum-diving.com/marine-life-koh-phangan/corals-more-cnidaria/true-jellyfish-scythozoa/scythozoa-other-jellyfish/|
And here's a blog that documents this brittle stars on the "hairy" jellyfish. Lobocnema
|Image by Thomas Peschak, https://www.thomaspeschak.com/|
Its also worth noting that the brittle stars stay on the medusae ONLY within their home range. Many of these jellies, such as Aurelia (i.e. moon jellies) actually go beyond tropical settings and they really aren't seen on jellies in cold to temperate waters..
3. So, what are the brittle stars EATING??
The authors used a novel new method which basically breaks down the organic components of specific isotopes (Carbon and Nitrogen) and looks for how much of those isotopes is present in the subjects versus that which is provided by the environment.
Long story short: The data indcates that most of the food sources in Ophiocnemis seems to come from PLANKTONIC SOURCES! (i.e. the mesozooplankton) and NOT from the medusae itself and there were not any observations of Ophiocnemis filter feeding (i.e. arms up in the water).
And so the authors suggest that they are what's called KLEPTOPARASITES (a great word-really!). In other words, they take food directly away from the jellyfish out of the mouth or the oral arms, stealing or scavenging food from the jellyfish which are known as big pelagic predators.. What would be called "indirect food sources"...
There are several reports of other brittle stars that practice "kleptoparasitc" behavior.. i.e. moving down into the feeding arms or near the mouth and stealing food directly from the host. Some of it might not be a big deal to the host.. scraps and etc.. but meaningful to the ophiuroids..
|Image by Ron Yeo at Tidechaser, http://tidechaser.blogspot.com/2012/03/brittle-stars-ophiuroidea-of-singapore.html|
4. Growth and Settlement..aka Living on a Changing Jellyfish World
|Image by Ron Yeo at Tidechaser http://tidechaser.blogspot.com/2012/03/brittle-stars-ophiuroidea-of-singapore.html|