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Reproduction and Life History



Two aquarium clownfish.
Picture taken by Elizabeth Guck


     Amphiprion ocellaris
have a unique life history and reproduction cycle because they are all protandrous hermaphrodites.  This means, that all species are born male with active male and dormant female reproductive organs.  Throughout their life, the fish is able to change from a male to a female if there is a need.  In each host anemone, there is only one female A. ocellaris and many males.  The female is the largest and most dominant fish in the group.  Her status can be compared to that of the head bee in a beehive (the "Queen Bee", or in this case, the "Queen Clownfish.")  She will only mate with the largest male in the bunch, thus, a hierarchy system is formed within the anemone.  All other male clownfish in the anemone are sexually immature.  If, for some reason, the female fish is removed from the anemone, the largest male will change sexes and become a female while the next largest male takes the place of the largest male.  This particular process allows the anemonefish to be self-sufficient within their host, and a search for a mate does not need to occur.


            Within each anemone, there is a monogamous mating pair.  Only the two largest fish, the male and female, mate, while all others are sexually inactive.  The process of reproduction begins with the male courting the female fish.  This courting is done through a process of extending his fins towards her, and then biting and chasing her around the anemone.  Oftentimes, the male becomes very aggressive during this spawning period.  Once the male has chased the female fish to the nest, the female will make several passes over the nest before releasing her eggs.  A female clownfish can release a clutch size ranging from 100 eggs, up to 1,000 eggs, depending on her age and size.  Amphiprion ocellaris eggs are orange and relatively small in size.  With the eggs released, the male then passes over the nest and fertilizes them.  Next, the eggs are attached to a substrate, which can be either a rock or some coral beneath the anemone’s oral discs, or in some extreme cases, debris around the host.  Once the eggs are attached, the male become their prime caregiver.  The males job is to fan the eggs to increase the amount of oxygen interacting with them, as well as to eat any unfertilized or damaged ones in order to keep the nesting site clean.  The hatching period for the eggs often depends on the temperature of the water.  On average, however, the eggs hatch between six and eight days.  Once the eggs have hatched, the pelagic larvae are independent from their parents.  This larval stage lasts anywhere from 14 to 21 days.  During this time, the young clownfish can often be found to school in other reef fish hatcheries, which provides protection to the fish without the need for a host anemone.  After this period, the fish undergo a phase change in which they become benthic juveniles.  It is then that they begin to search for a host sea anemone to live in.  (See also Habitat and Adaptations).  Amphiprion ocellaris are mostly sedentary creatures following this settlement and only migrate between hosts if they are close together.  A clownfish can survive in the wild up to ten years.


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