There are many strange yellow cells deep within the tissues of jellyfish, corals and sea anemones that are genetically different from marine animals.
A new paper, more than 100 years after the first assignment of these cells to a forgotten genus has revived the name and described six species from all over the globe.
"Because we have scientists from seven different countries, we were in a position to collect all these samples and some during the global epidemic," stated Todd LaJeunesse, Penn State University's lead author.
"This study shows how scientific discovery can bring people together even during times of hardship."
The yellow things, first described in 1881 by Karl Brandt, were initially classified under the genus Zooxanthella. Brandt also invented the term Zooxanthellae which is still used in common parlance to this day.
Patrick Geddes, a Scotsman scientist, was also investigating the yellow cells. Geddes, who had not seen Brandt's work in 1882, discovered that the cells were separate from the animals within them (something Brandt also confirmed), and that they were mutualistic symbiotes.
Philozoon was the genus Geddes created to categorize these cells. It is derived from the Greek words for to love as a friend' or 'animal'. Brandt was the first to use the Philozoon Genus, so Geddes moved on to urban planning and was quickly forgotten about the new genus.
Now we know that the odd microorganisms Geddes & Brandt studied back in the day were photosynthetic dinoflagellates single cellled algae found in symbiosis.
Researchers used genetic data, geographic data, and morphology to examine these yellow cells in a new study. This analysis revealed where they should be placed in the genetic tree.
After deciding that these creatures needed to be placed into a new genera, the team took Philozoon from retirement for six new species and two of the old species.
The team stated that they had emended the genus Philozoon Geddes, two of its species, P. Medusarum and P. Actiniarum, as well as six new species.
"Each symbiont type exhibits high host fidelity to particular species of sea anemones, soft corals, stony corals, and a Rhizostome jellyfish."
Philozoon can be found in shallow, warm marine habitats all over the globe, including the Mediterranean Sea and New Zealand.
LaJeunesse explains that Symbiodiniaceae's majority of the species are tropical and therefore, it is important to find and describe new species in cold water. This demonstrates the ability of these symbioses for evolution and survival in a wide range of environments.
"Life finds a way for it to continue and proliferate."
The European Journal of Phycology published the research.