Spinecheek anemonefish, Premnas biaculeatus, are found in the Indo-West Pacific, including the coasts of India, Burma, Thailand, Malaysia, Indonesia, Philippines, New Guinea, New Britain, Solomon Islands, Vanuatu and northern Queensland. (Capuli and Santos, 2006)
The most important aspect of spinecheek anemonefish habitat is the host anemone. Entacmaea quadricolor, bulb-tentacle sea anemones, are the only host species for spinecheek anemonefish. This anemone species is characterized by polyps 50 to 400 mm in diameter, depending on depth. They have brown tentacles of about 100 mm long with a red tip and white bulb at the end of the tentacle. Spinecheek anemonefish tend to live mainly in solitary specimens of Entacmaea quadricolor on reef slopes. The typical water depth is less than 50 m, because anemones require sunlight to grow. The mutualistic zooxanthellae (living within the anemone) need this sunlight to photosynthesize and provide energy for themselves and the anemone. These anemone prefer tropical warm waters with the temperature ranging between 25 and 28°C (77-82°F). (Fautin and Allen, 1992)
Spinecheek anemonefish are among the easiest anemonefish to identify, even when young. They are bright red with 3 bars that are bright white in males and grey in females. Individuals may become bright white if they are provoked. The lines may also be bright yellow. (Fautin and Allen, 1992)
The developmental stages of spinecheek anemonefish are egg, larvae, young and adult. The transparent, elliptical eggs are 3-4 mm in size. Anemonefish hatch with advanced alimentary canals and feed on the yolk, which usually lasts for about 3 days. Five days after hatching they develop supranuclear inclusions around the hindgut, which suggests pinocytotic digestion of protein. Between 3 to 5 days after hatching is the period of highest mortality stage for anemonefish if they cannot find food. It is also the time when they transition from endogenous to exogenous feeding. Seven days after hatching they attain gastric glands and by the 9th day they have supranuclear vacuoles that indicate exogenous digestive capabilities. Spinecheek anemonefish hatch 6 to 7 days after fertilization, and then undergo a 7 to 14 day pelagic larval stage. After fertilization, they complete the development of the olfactory organ in 19 days, retinal differentiation in 20 days and skeletal ossification in about 22 days. Spinecheek anemonefish develop more rapidly than other anemonefish species. Their eyes develop especialy rapidly. Vision is directly correlated with the ability to attain food because most larval fish are visual feeders. Olfactory cues are used to detect host anemones. During the larval stage spinecheek anemonefish live on the water surface where they are transported by currents. (Coughlin, 1994; Gordon and Hecht, 2002; Job and Bellwood, 1996; Kavanagh and Alford, 2003)
Metamorphosis occurs when anemonefish leave surface waters and swim to the sea bottom. It then takes on the color pattern of a juvenile. This process usually takes about one day. This marks the beginning of the settlement period, in which individuals seek out an uninhabited anemone host. (Coughlin, 1994; Gordon and Hecht, 2002; Job and Bellwood, 1996; Kavanagh and Alford, 2003)
Spinecheek anemonefish, like other anemonefish species, are protandrous hermaphrodites, which means that they change from male to female. Females have gonads that function as ovaries with leftover male testicular tissue. In the case of spinecheek anemonefish, males may be half the size of females and their gonads have dormant ovarian cells as well as functioning testes. (Fautin and Allen, 1992)
Spinecheek anemonefish have a monogamous mating system and mated pairs may stay together for several years. The dominant female is the largest and has one partner, which is the next largest male within a cluster of anemones. The growth of other anemonefish in the same anemone patch is stunted by the presence of a dominant male and female, keeping them smaller than the dominant male. When one or the other of the dominant individuals dies, subordinates grow and replace the dead individual. For example, if the dominant male dies, the next largest male will replace him and continue to grow to its maximum size. (Fautin and Allen, 1992)
Males, before spawning, go through an extensive ritual of courtship that consists of displaying the dorsal, anal and pelvic fins. He also chases and nips his mate. (Fautin and Allen, 1992)
Spinecheek anemonefish may spawn throughout the year in tropical areas. In cooler water they may spawn during the warm season. (Fautin and Allen, 1992)
Males care primarily for the eggs. Before spawning, males find and prepare a nest for the eggs. He cleans the area by removing the debris and algae from the area. Usually the female ends up joining in the task. During incubation the male guards and cares for the nest. He chases away any possible predators that may want to feast on the eggs, such as wrasses. Male anemonefish use their pectoral fins to fan the eggs and spend time meticulously removing dead eggs and debris from the nest with their mouths. Females will occasionally assist males but mainly spend their time feeding. (Fautin and Allen, 1992)
The lifespan of spinecheek anemonefish has not been well researched. They live longer in the wild, ranging from 6 to 10 years, and about 3 to 5 years in captivity under good conditions. A related species, Amphiprion perideraion, was recorded living to 18 years. (Fautin and Allen, 1992; Kramer, 2005)
Spinecheek anemonefish have a social hierarchy in which fish that occupy the same patch of anemones are ordered in status by size. Generally there is a breeding pair and then 0 to 4 non-breeders. The largest is the female of the group (highest rank), followed by the largest male, who is part of the breeding pair. In the case of the death of the female, the second largest changes from male to female. Size difference is maintained in order to avoid subordinates becoming a threat to the highest ranking male. There is an average difference of 10 mm between ranks in the related anemonefish, Amphiprion percula. When a dominant anemonefish dies, the next subordinate moves up in the rank order and grows further. (Buston, 2003)
Spinecheek anemonefish are active during the day. Once they settle onto an anemone as a juvenile, and then adult, they remain in the same area throughout their life.
Spinecheek anemonefish are territorial, defending the area around their host anemone. Usually one anemone hosts the breeding pair and 4 to 5 other non-breeding males. (Buston, 2003; Fautin and Allen, 1992)
Mates communicate in courtship through movement and touch. During spawning, females swim in a zig-zag pattern over the nest while the male fertilizes the eggs. Males also “shows off” their fins to females, a form of visual communication. (Fautin and Allen, 1992; Fautin and Allen, 1992)
The most vulnerable stage for spinecheek anemonefish is during the egg and larval stage, when they are not protected by a host anemone and float freely in the water column. As settled adults, Entacmaea quadricolor protects these symbiotic fish because of their ability to deliver a venomous sting. Wrasses are known to prey on eggs and other fish are likely predators of eggs, larvae, and unsettled juveniles. (Coughlin, 1994; Fautin and Allen, 1992)
Spinecheek anemonefish and their host anemones have a mutualist relationship. Entacmaea quadricolor benefits from having spinecheek anemonefish protect them from butterflyfish (Chaetodontidae), which would otherwise eat their tentacles. Spinecheek anemonefish also clean away debris and parasites from the anemone. Spinecheek anemonefish are protected from most predators through their association with venomous anemones.
Spinecheek anemonefish are important to the aquarium suppliers who sell them for profit. These anemonefish, and their relatives, are important ecotourist draws for diving operations. Their symbiotic relationship with Entacmaea quadricolor, helps to protect these anemones.
There are no known adverse effects of the spinecheek anemonefish on humans.
Although spinecheek anemonefish are not endangered, there are concerns for populations and their reef habitats due to the "Nemo craze". In the last generation 15 to 30% of the world's reefs have been lost. After release of Disney's "Finding Nemo" movie, which has an anemonefish as its main protagonist, anemonefish sales have increased. Collecting methods are often extremely destructive, permanently damaging reefs. (Osterhoudt, 2004)
Tanya Dewey (editor), Animal Diversity Web.
Johanna Higuera (author), University of Notre Dame, Karen Francl (editor, instructor), Radford University.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
fertilization takes place outside the female's body
union of egg and spermatozoan
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
Having one mate at a time.
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
the business of buying and selling animals for people to keep in their homes as pets.
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
condition of hermaphroditic animals (and plants) in which the male organs and their products appear before the female organs and their products
structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
breeding takes place throughout the year
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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