Coelenterates are dioecious, meaning they have separate male and female individuals. This characteristic distinguishes them from monoecious organisms, which have both male and female reproductive organs in the same individual.

Definition of Coelenterates
Coelenterates, also known as cnidarians, are a diverse group of invertebrate animals that includes jellyfish, sea anemones, and corals. They are characterized by the presence of specialized cells called cnidocytes, which contain stinging structures called nematocysts. Coelenterates exhibit a radial symmetry and have a central cavity called the gastrovascular cavity that serves both as a digestive and circulatory system.

Dioecious Reproduction in Coelenterates
Coelenterates reproduce sexually, and most species are dioecious. This means that individual coelenterates are either male or female. Dioecious organisms have separate male and female reproductive organs and produce separate male and female gametes. In coelenterates, the gametes are released into the surrounding water for fertilization.

Sexual Dimorphism in Coelenterates
In dioecious coelenterates, there may be distinct differences between male and female individuals, known as sexual dimorphism. These differences can include variations in size, shape, coloration, or the presence of specialized structures for reproduction. For example, in some jellyfish species, the females are larger and have longer tentacles compared to the males.

Advantages of Dioecious Reproduction
Dioecious reproduction offers several advantages for coelenterates. First, it promotes genetic diversity within the population by combining genetic material from different individuals. This genetic diversity can be beneficial for the survival and adaptation of the species to changing environmental conditions. Second, dioecious reproduction allows for specialization in reproductive roles, with each sex having specific adaptations for successful reproduction.

Exceptions to Dioecious Reproduction
While most coelenterates are dioecious, there are some exceptions to this rule. Some species, particularly those belonging to the class Anthozoa which includes sea anemones and corals, are monoecious. Monoecious coelenterates have both male and female reproductive organs within the same individual. This allows for self-fertilization or cross-fertilization with other individuals. Monoecious coelenterates often have mechanisms to prevent self-fertilization, such as temporal separation of male and female gamete production.

In conclusion, coelenterates are generally dioecious, having separate male and female individuals. Dioecious reproduction promotes genetic diversity and specialization in reproductive roles. However, there are exceptions, such as some species of coelenterates that are monoecious, possessing both male and female reproductive organs within the same individual.

Colenterates are monoecious with protoandrous condition