Two new species of mushroom-shaped creatures from the deep sea have been described, after scientists failed to place them in any of the recognised groups of animals.
A new family, Dendrogrammatidae, has been established for the mystery creatures, which have been named Dendrogramma enigmatica and D. discoides. The creatures are made up of an outer skin and inner stomach, separated by a dense layer of jelly-like material. The body is divided into a stalk with a mouth opening terminally, and a flattened disc.
They were discovered in 1986 when they were dredged up from depths of 400m and 1000m on the south-east Australian continental slope, near Tasmania. Researchers now think they may represent an early branch on the tree of life.
Although Dendrogramma shares a number of similarities in general body organisation with the phyla Ctenophora and Cnidaria, scientists say that they cannot be placed inside any of these.
They add that judging by the construction of the two Dendrogramma species, neither appears able to swim. They have a small, simple mouth, suggesting they feed on micro-organisms, which are possibly trapped by mucus from specialised lobes surrounding the opening of the mouth.
The result of the study is published in PLOS ONE. For more information see the paper: Just J, Kristensen RM, Olesen J (2014) Dendrogramma, New Genus, with Two New Non-Bilaterian Species from the Marine Bathyal of Southeastern Australia (Animalia, Metazoa incertae sedis) – with Similarities to Some Medusoids from the Precambrian Ediacara. PLoS ONE 9(9): e102976. doi:10.1371/journal.pone.0102976
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