''Hoilungia hongkongensis'' is a species in the phylum

Placozoa The Placozoa are a basal form of marine free-living (non-parasitic) multicellular organism. They are the simplest in structure of all animals. Three genera have been found: the classical ''Trichoplax adhaerens'', '' Hoilungia hongkongensis'', a ...

. The organism appears superficially similar to ''

Trichoplax adhaerens ''Trichoplax adhaerens'' is one of the three named species in the phylum Placozoa. The others are '' Hoilungia hongkongensis'' and '' Polyplacotoma mediterranea''. The Placozoa is a basal group of multicellular animals (metazoa). ''Trichoplax'' ...

'', but genetic analysis of its mitochondrial DNA shows numerous differences. It was discovered in brackish water from mangrove swamps in Hong Kong. These organisms are generally found in the

biofilm A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...

surfaces in tropical and subtropical environments. Phylogenetically, they are placed closest to cnidarians. They are diploblastic animals and are believed to have dorso-ventral polarity along top and bottom body layers. Their body is overtly similar to oral-aboral axis of cnidarians. They feed from lower tissue layer which has various peptidergic gland cells. They feed on algae, bacteria, yeast and other byproducts of biofilms. They reproduce asexually through binary fission and there is also some evidence of sexual reproduction. The ''Hoilungia hongkongensis'' genome adds support to the phylogenetic placement of the Placozoa in the animal tree of life

Natural history

Over a long time, only a single species of placozoan clades, ''

'', was described but lately, it has been found that the relatively newer species, ''Hoilungia hongkongensis'' is a result of reproductive isolation mechanism of speciation.

Nitric oxide signaling

''Hoilungia'' and ''Trichoplax'' are considered one of the earliest branching animal lineages, and have relatively simple morphologies their complexity of NO-cGMP-mediated signaling is greater to those in vertebrates. This evidence has been found in their DNA by experimentation using ultra-sensitive capillary electrophoresis assays.

Etymology

The genus name is derived from the phrase "hoi lung", which means "sea dragon" in Cantonese.

Structure

The body axis of ''Trichoplax'' and the new placozoan species, ''Hoilungia hongkongensis'', is overtly similar to the oral–aboral axis of cnidarians.

References

Placozoa Fauna of Hong Kong Monotypic animal genera Animals described in 2018 Parazoa {{animal-stub