Tima nigroannulata

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 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 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.

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.

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