Clownfish in the context of "Spawn (biology)"

Symbiosis is any close and long-term biological interaction between two organisms of different species. In 1879, Heinrich Anton de Bary defined symbiosis as "the living together of unlike organisms". The term is sometimes more exclusively used in a restricted, mutualistic sense, where both symbionts contribute to each other's subsistence. This means that they benefit each other in some way.

Symbiosis is diverse and can be classified in multiple ways. It can be obligate, meaning that one or both of the organisms depend on each other for survival, or facultative, meaning that they can subsist independently. When one organism lives on the surface of another, such as head lice on humans, it is called ectosymbiosis; when one partner lives inside the tissues of another, such as Symbiodinium within coral, it is termed endosymbiosis. Where the interaction reduces both parties' fitness, it is called competition; where just one party's fitness is reduced, it is called amensalism. Where one benefits but the other is largely unaffected, this is termed commensalism. Where one benefits at the other's expense, it is called parasitism. Finally, where both parties benefit, the relationship is described as mutualistic.

Sea anemones (/əˈnɛm.ə.ni/ ə-NEM-ə-nee) are a group of predatory marine invertebrate animals constituting the order Actiniaria. Because of their colourful appearance, they are named after the Anemone, a terrestrial flowering plant. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Hexacorallia.As cnidarians, sea anemones are related to corals, jellyfish, tube-dwelling anemones, and Hydra. Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle.

A typical sea anemone is a single polyp attached to a hard surface by its base, but some species live in soft sediment, and a few float near the surface of the water. The polyp has a columnar trunk topped by an oral disc with a ring of tentacles and a central mouth. The tentacles can be retracted inside the body cavity or expanded to catch passing prey. They are armed with cnidocytes (stinging cells). In many species, additional nourishment comes from a symbiotic relationship with single-celled dinoflagellates, with zooxanthellae, or with green algae, zoochlorellae, that live within the cells. Some species of sea anemone live in association with clownfish, hermit crabs, small fish, or other animals to their mutual benefit.

The ocellaris clownfish (Amphiprion ocellaris), also known as the false percula clownfish or common clownfish, is a marine fish belonging to the family Pomacentridae, which includes clownfishes and damselfishes. Amphiprion ocellaris are found in different colors, depending on where they are located. For example, black Amphiprion ocellaris with white bands can be found near northern Hawaii, USA, North America, Australia, Southeast Asia, and Japan. Orange or red-brown Amphiprion ocellaris also exist with three similar white bands on the body and head. Amphiprion ocellaris can be distinguished from other Amphiprion species based on the number of pectoral rays and dorsal spines. Amphiprion ocellaris are known to grow about 11 cm (4.3 inches) long. Like many other fish species, females are, however, larger than males. The life cycle of Amphiprion ocellaris varies in whether they reside at the surface or bottom of the ocean. When they initially hatch, they reside near the surface. However, when Amphiprion ocellaris enter into the juvenile stage of life, they travel down to the bottom to find shelter in a host anemone. Once they find their anemone, they form a symbiotic relationship with them.