DENDROGRAMMA, THAT MUSHROOM-SHAPED DEEP SEA ORGANISM IS IN A SIPHONOPHORE (oh well.. in part)
In 2014 researchers reported a weird mushroom-shaped organisms from the deep sea off south-eastern Australia. These organism related at first with jellyfish and comb jellyfishes, were called Dendrogramma. At that moment they were a total mistery, they have no appendages or special cells to recognize them with other animals. Yet nothing is known about their lifestyle, their feeding habits, how they reproduce or if they float or attach to the seafloor. Although they were collected in 1986, there have been no genetic studies on the species, hitherto.
Dendrogramma is indeed a bizarre animal, was the iconic deep-sea animal of 2014, voted among the top-ten new species described that year. But the authors could not assign the new genus to any known animal group with certainty, leading to numerous media reports that it belonged to an entirely new kind of animal, without similes in nature.
But a new study, using DNA analysis indicates that the Dendogramma organism are not an entire animals, just the pieces of a siphonophore, cnidarian related to jellyfish, corals and anemones. Although a siphonophore appears to be a single organism, each specimen is actually a colony composed of highly specialised individual animals called zooids
- Dendrogramma in the tree of animal life.
Previously considered as two species, researchers concluded that is just one species, appropriately named Dendrogramma enigmatica. Although an entire Dendrogramma colony has not been found, researchers believe that the mushroom-like bodies are bracts, possibly used to aid buoyancy or as defensive appendages to protect feeding gastrozooids or gonads.
The discoid things with stalks would be cormidial bracts. Bracts are usually leaf-like structure with a simple bracteal canal. The figure shows those bracts in an entire siphonophore. Reference here.
Reference: O’Hara et al. 2016. Dendrogramma is a siphonophore. Cell
Photograph: Dendrogramma enigmatica by David Paul and Rebecca McCauley/Museum Victoria
