The Migration of Clownfish

Clownfish are a unusual species of fish that mate for life and form a symbiotic relationship with sea anemones, which provide them with year-round food, protection and shelter. For these reasons, adult clownfish are non-migratory. However, clownfish hatchlings are carried out into the open ocean and must travel to return to their original reef or find a new location to call home.

  1. Symbiosis with Sea Anemones

    • Adult clownfish make their homes in and around sea anemones. They do not have to migrate from their homes to find food, shelter or alternative living conditions because sea anemones provide a safe living environment for the fish year-round.These plant-like animals sport tentacles that sting any predators. Clownfish are immune to the stings because their bodies are covered with thick mucus. Besides making a home among sea anemones' tentacles, clownfish are also able to eat the leftover fish, shrimp and crinoids that the sea anemones catch and consume. In return, the clownfish help protect their sea anemones by chasing away predators.

    Mating Patterns

    • Mature clownfish mate for life and remain monogamous as long as both partners are living in the same anemone. A given sea anemone can contain a large female clownfish and a somewhat smaller and highly territorial male. Sometimes a few juvenile clownfish occupy the anemone as well. If the female dies or disappears from the anemone, the male partner changes its sex to become the lead female. One juvenile then matures rapidly to become the anemone's lead male. This way, adult clownfish always have a mate, and do not need to migrate to breed.

    Reproduction

    • Adult clownfish lay their eggs on the solid substrate to which their sea anemones' homes are attached. The eggs, like their parents, are protected from predators by the anemone's stinging tentacles. However, after a week of being attached to the substrate, the eggs detach and float out into the open ocean for between 10 and 14 days. The eggs hatch into larval clownfish during this period, after which they swim to find a reef to call home.

    Juvenile Migration

    • Studies have found that 60 percent of young clownfish that are carried by ocean currents away from their homes return to their original reef to spend their juvenile period, while 40 percent of young clownfish find a new reef at least 5 miles away from home. Juvenile clownfish live in a sea anemone nest with a mated pair of adults until they reach maturity, after which they are driven away by the anemone's territorial, dominant male to find their own anemone on the same reef.