''Tima nigroannulata'', commonly known as the elegant jellyfish, is a recently discovered colonial

hydrozoa Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specializ ...

found on the Pacific coast of Japan.

Taxonomy

''Tima nigroannulata'' is in the genus ''Tima'' and belongs to the order

Leptothecata Leptothecata, or thecate hydroids, are an order of hydrozoans in the phylum Cnidaria. Their closest living relatives are the athecate hydroids, which are similar enough to have always been considered closely related, and the very apomorphic Siph ...

within the class Hydrozoa. ''Tima nigroannulata'' are a part of the family

Eirenidae Eirenidae is a family of hydrozoans Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be l ...

, that include colonial

cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that th ...

ns like jellyfish, sea anemones, corals, hydras, and other related organisms. Due to the evolutionary relationships of Eirenidae needing more research, its closest relatives are unknown. There are other species of ''Tima'' that belong to the family Eirenidae that share a few morphological characteristics like the forming of a branched colony with hydrothecae. More research is needed to better understand its relationship to other species.

Habitat and distribution

''Tima'' has been found in various marine environments including warm, shallow tropical waters and the deep sea. ''Tima'' has been found in the Gulf of Mexico, Caribbean Sea, and the southeastern coast of the United States. ''T. nigroannulata'' was initially found in the shallow waters on the Pacific coast of Japan. ''Tima nigroannulata'' is a species commonly found growing on rocks and shells as polyps and drifting through the water as

medusae Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella- ...

Description

''Tima nigroannulata'' is a small, gelatinous, marine animal that does not have distinctive or complex organs or tissue. It is a colonial hydrozoan, so it consists of multiple individual organisms

zooid A zooid or zoöid is a single animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zooi ...

that form a large colony. Individual zooids are cylindrical in shape and small in size. ''T. nigroannulata'' is hemispherical, approximately the size of a human hand, and can have over 50 tentacles. Their bodies are translucent and has

mesoglea Mesoglea refers to the extracellular matrix found in cnidarians like coral or jellyfish that functions as a hydrostatic skeleton. It is related to but distinct from mesohyl, which generally refers to extracellular material found in sponges. Descr ...

that is found between two layers of living cells. ''T. nigroannulata'' has zooids with tentacles that are specialized for various functions like feeding, defense, reproduction and sensory perception to a certain degree. The large colony has branches that are composed of various zooids that are arranged in a fan like pattern. Its name comes from the dark annular rings surrounding the base of each individual zooid that gives its rather pigment less body a distinctive look.

Reproduction and life cycle

More research needs to be done to better understand the reproductive and life cycle of ''T. nigroannulata''. Because ''T. nigroannulata'' was found from medusae, it is currently understood that their life cycle consists of both polyp and medusa stages. According to current literature, ''T. nigroannulata'' follows similar reproductive and life cycle like other hydrozoans. This begins with the release of

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce t ...

s from the adult polyps into the water column. These gametes are fertilized to then become zygotes that develop into

planula A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species and also in some species of Ctenophores. Some groups of Nemerteans also produce larvae that are very similar to the planula, which ...

. The planula settles onto a hard substrate like a rock where it continues to develop into a small polyp that eventually becomes a large adult colony. Some of the polyps will metamorphizes into medusae which specialize in sexual reproduction by releasing gametes into the water, starting the process over. Those who remain polyps may undergo asexual reproduction through budding and polyp fission (fragmentation).

Feeding

It is possible for ''T. nigroannulata'' to have similar dietary habits to other hydrozoans, but there is limited research on their diet specifically. Hydrozoans are diverse in their feeding habits. Some are filter feeders that consume particles from the water column while others utilize the tentacles of the zooid to trap small planktonic organisms like

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

. Based on literature, their predation may be influenced by the depth at which they are found as that effects the distribution and availability of prey. ''Tima nigroannulata'' like other jellyfish provide a source of food to various predators making them a key component in

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

environments.

Similar species

There are other species within the ''Tima'' genus. Many of them are understudied as they are fairly recent findings. When ''T. nigroannulata'' was discovered, it was initially believed to be another hydrozoan by the name of ''

Tima formosa ''Tima formosa'' is a colonial species of marine hydrozoan in the family Eirenidae. They live in northern parts of the Atlantic Ocean, in the upper epipelagic zone. It is also the name of a 2010 album by musical artist Oren Ambarchi with Jim ...

''. The two hydroids look fairly similar and share characteristics of their class, but genetic testing proved that they are two distinct species. Tima formosa1

References

{{Taxonbar, from=Q110050077 Wikipedia Student Program Eirenidae Animals described in 2021