Premnas biaculeatus

Geographic Range

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.

• Biogeographic Regions
• indian ocean
  • native native
• pacific ocean pacific ocean
  • native native

Habitat

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).

• Habitat Regions
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• reef reef
• coastal coastal

Physical Description

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.

• Other Physical Features
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• male more colorful

Development

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.

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.

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.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

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.

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.

• Mating System
• monogamous monogamous

Spinecheek anemonefish may spawn throughout the year in tropical areas. In cooler water they may spawn during the warm season.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sequential hermaphrodite
  • protandrous protandrous
• sexual sexual
• fertilization fertilization
  • external external
• oviparous oviparous

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.

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • male

Lifespan/Longevity

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.

Behavior

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.

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.

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Home Range

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.

Communication and Perception

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.

• Communication Channels
• visual visual
• tactile tactile

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Spinecheek anemonefish have a diet rich in copepods and planktonic, larval tunicates . They also eat other kinds of plankton and algae.

• Primary Diet
• carnivore carnivore
  • eats non-insect arthropods
  • eats other marine invertebrates

• Animal Foods
• aquatic or marine worms
• aquatic crustaceans
• other marine invertebrates
• zooplankton zooplankton

• Plant Foods
• algae
• phytoplankton phytoplankton

Predation

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.

Ecosystem Roles

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.

Economic Importance for Humans: Positive

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.

• Positive Impacts
• pet trade pet trade
• ecotourism ecotourism
• research and education

Economic Importance for Humans: Negative

There are no known adverse effects of the spinecheek anemonefish on humans.

Conservation Status

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.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Johanna Higuera (author), University of Notre Dame, Karen Powers (editor, instructor), Radford University.

References

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Capuli, E., C. Santos. 2006. "Premnas biaculeatus" (On-line). FishBase. Accessed April 11, 2006 at http://fishbase.org/summary/speciessummary.php?id=6632 .

Coughlin, D. 1994. Suction Prey Capture by Clownfish Larvae (Amphiprion perideraion). Copeia , 1: 242-246.

Fautin, D., D. Allen. 1992. Field Guide to Anemone Fishes and their Host Sea Anemones . Perth, WA 6000 Australia: Western Australian Museum. Accessed April 11, 2006 at http://www.nhm.ku.edu/inverts/ebooks/intro.html .

Gordon, A., T. Hecht. 2002. Histological studies on the development of the digestive system of the clownfish Amphiprion percula and the time of weaning. J. Appl. Ichthyol. , 18: 113-117. Accessed April 11, 2006 at www.blackwell.de/synergy .

Job, S., D. Bellwood. 1996. Visual acuity and feeding in larval Premnas biaculeatus. Journal of Fish Biology , 48: 952-963.

Kavanagh, K., R. Alford. 2003. Sensory and skeletal development and growth in relation to the duration of the embryonic and larval stages in damselfishes. Biological Journal of the Linnean Society , 80: 187-206.

Kramer, S. 2005. "An Exploration of the Clownfish" (On-line). Tree of Life Web Project. Accessed April 11, 2006 at http://tolweb.org/treehouses/?treehouse_id=3390 .

Osterhoudt, S. 2004. Buying Nemo. E Magazine , July/August: 10.

Wikipedia.com, 2006. "Maroon Clownfish" (On-line). Wikipedia.com. Accessed April 11, 2006 at http://en.wikipedia.org/wiki/Maroon_Clownfish .

Columbia University Press. 2000. "Life on the Reef: The Amazing World of Coral Fishes" (On-line). The National History Museum. Accessed April 11, 2006 at http://www.fathom.com/course/2170172/session1.html .