Narcomedusae
Narcomedusae are a small order of hydrozoans within the class Hydrozoa, a group of predominantly marine invertebrates. They are characterized by their unique morphology and lifestyle, which distinguish them from other hydrozoans.
Common Names
Narcomedusae are often referred to as "narcomedusians," though there are no commonly used vernacular names for these organisms.
Characteristics
Narcomedusae are distinguished by the following characteristics:
- Medusa Stage Dominant: Unlike many other hydrozoans, narcomedusae spend the majority of their life cycle in the medusa stage, which is the free-swimming, jellyfish-like form.
- Lack of Polyp Stage: Narcomedusae lack a polyp stage, the sessile, attached stage found in many other hydrozoans.
- Reduced Tentacles: They typically have reduced tentacles compared to other hydrozoans, and their tentacles are often branched or filamentous.
- Mesoglea: Their mesoglea, the gelatinous layer between the epidermis and gastrodermis, is thick and contains a network of muscle fibers.
- Gastrovascular System: Narcomedusae have a complex gastrovascular system with numerous canals and chambers, which facilitate digestion and nutrient transport.
- Reproduction: They reproduce sexually, with the medusa releasing sperm and eggs into the water.
Environment
Narcomedusae are predominantly found in oceanic environments, particularly in the open ocean and deep sea. They are often associated with plankton communities, where they serve as predators of smaller organisms.
References
Narcomedusae: A Review of Their Biology, Evolution, and Phylogeny
Narcomedusae - an overview | ScienceDirect Topics