Diversity
Pomacentrids, commonly known as damselfishes and anemonefishes, are one of the most
abundant and widely-studied families of tropical reef fishes. Small and brightly
colored, they are popular aquarium fish. The family Pomacentridae consists of approximately
28 genera and 335 species. They tend to be territorial and can be aggressive, although
this is not the case for the non-territorial, free-swimming planktivores or the anemonefishes
(
Amphiprion
and
Premnas
) that live commensally with anemone hosts. Damselfishes are largely herbivorous,
sometimes tending “gardens” of filamentous algae, but may eat tiny invertebrates,
or in the case of anemonefishes, anemones and other organisms living symbiotically
with anemones. Damselfishes manifest a range of reproductive behaviors, with groups
that are polygynous, promiscuous, polyandrous, and monogamous. Anemonefishes are
able to change from male to female under certain conditions (see Reproduction: Mating
Systems).
Geographic Range
Pomacentrids are found throughout the world in tropical and warm temperate waters,
with the majority of species occurring in the Indo-west and central Pacific region.
- Biogeographic Regions
- oriental
- ethiopian
- neotropical
- australian
- oceanic islands
- indian ocean
- atlantic ocean
- pacific ocean
- Other Geographic Terms
- cosmopolitan
Habitat
Pomacentridae primarily inhabit tropical reef habitats. Some live along steep edges
of the reef, and others in sandy sheltered lagoons. In each ocean a few species occupy
warm temperate waters, and three estuarine species can sometimes be found in fresh
water. Some school in the water column, some live on rocky areas or sea-grass beds,
and fishes of the subfamily
Amphiprionina
(anemonefishes) always dwell in association with
sea anemones
. A few deep-water species occur at the edge of the shelf at depths below 100 m,
but most pomacentrids occupy shallow water between two and 15 meters deep.
- Habitat Regions
- temperate
- tropical
- saltwater or marine
- Aquatic Biomes
- benthic
- reef
- coastal
- brackish water
Physical Description
Damselfishes, which include the anemonefishes (
Amphiprion
and
Premnas
), range from five to 36 cm, with most specimens less than a foot long. Their bodies
tend to be high, oval and laterally compressed, with the lateral line interrupted.
The single, continuous dorsal fin has eight to 17 spines and 10 to 18 soft rays, the
anal fin usually has two spines (occasionally three), and the caudal fin is typically
forked. Adults of many species have filamentous extensions on all but the pectoral
fins.
Ctenoid scales
are present on the body, head, and unpaired fin bases. Pomacentrids, with a few
exceptions, have one rather than two nostrils on each side, and a small mouth. The
palate is toothless, and the floor of the mouth contains a pharyngeal plate (a triangular
fused tooth plate). Teeth may be arranged in one or two rows and may be incisorlike,
especially in territorial forms that graze on algae, or conical, often seen in forms
that live in the water column and catch small organisms (See an illustration of
tooth morphology in fish
). Coloration of adult damselfishes ranges from brilliant to drab and can vary with
mood and time of day. Juveniles, especially in the territorial bottom-dwellers, often
possess different, brighter colors than adults of the same species. (Click here to
see a
fish diagram
).
In most pomacentrid groups males and females differ (
sexual dimorphism
) externally only in the form of the urogenital papilla, and (except for one species)
lack permanent sexual dichromatism. The majority, however, do assume sex-specific
colors during spawning. Usually the male, but sometimes the female (and sometimes
neither), assumes courtship colors, the pattern and intensity of which vary according
not only to species, but also to geographic and perhaps other factors. Adult males
tend to be larger than adult females, but the opposite is true for anemonefishes (
Amphiprion
and
Premnas
), which are protandrous hermaphrodites: a male can change sex if the dominant female
(the largest fish in the group) dies. In these fishes a single individual possesses
ovarian as well as testicular tissue.
- Other Physical Features
- ectothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
- female larger
- male larger
- sexes colored or patterned differently
- male more colorful
Development
Pomacentrid larvae hatch from a clutch of 50 to 2500 eggs, depending on the species.
For some the planktonic stage may last only a day while others drift in the open ocean
for a few weeks. Juveniles settle in reef areas and their coloration can be quite
different from that of adults of the same species. In anemonefishes (
Amphiprion
and
Premnas
) one sexually active pair is dominant over a group of juveniles. The young grow
slowly in this situation and do not reach sexual maturity until they can replace one
of the dominant fish.
Reproduction
The majority of damselfishes engage in a range of ritualized behavior to attract mates
and prepare nest sites. The male, and sometimes the female, begin to groom and tend
a rocky surface several days before spawning. He removes invertebrates and algae
with his mouth, sometimes allowing certain elements to remain, as is the case with
Hypsypops rubicundus
, a species that weeds out all but red algae from the site. Courtship activities accompany
cultivation of the potential nest. Males may give auditory signals; depending on
the stage of courtship, species of
Eupomacentrus
emit three different types of chirps and grunts. They may also display visual signals,
with most damselfish males assuming distinct colors for courtship, and many executing
various movements to entice the female to the nest site. Such movements have been
described as “leading,” which may include quick bursts of swimming and intermittent
hovering in front of the female, “signal-jumping,” or rapid up and down movements,
and “dipping,” which is similar to signal-jumping and includes an abrupt descent.
One group of damselfishes, the anemonefishes (subfamily
Amphiprioninae
), enter into permanent monogamous pairings and as a rule display a simplified pattern
of courtship. Fish in this subfamily are protandrous, a mating system in which male
individuals can become female. Ambosexual (neither sperm- nor egg-producing tissues
are active) juveniles live on an anemone with a sexually mature male and female pair.
If the female dies, her male partner develops into a female to take her place. The
largest juvenile grows rapidly and replaces him as the dominant male.
- Mating System
- monogamous
- polyandrous
- polygynous
- polygynandrous (promiscuous)
Damselfishes appear to spawn year-round, with many groups increasing spawning activity
in early summer. In the subtropics spawning is usually limited to the warmer months
of the year, but a few spawn in fall or winter. It is common for reef-dwelling damselfishes
to spawn in accordance with lunar rhythms, with greatest activity occurring near the
full and new moons. Spawning usually takes place in the morning. Synchronous spawning
has been observed, and in some species, the higher the number of individuals in a
group, the higher the degree of synchrony. Some damselfishes spawn within their permanent
territory, while others (planktivorous damselfishes that live in the water column)
must seek temporary territories for courtship and spawning. Location of a spawning
site may involve solitary males or may be a communal activity in which schools of
males, juveniles, and females travel until the males form a colony of territories
on an acceptable site. Site choice varies according to species and may include rock
ledges, cleaned coral branches, algal turf, empty shells, or the roofs of caves.
Males typically prepare the site for spawning and then attract gravid (egg-bearing)
females to the nest (see Reproduction: Mating Systems). The male guards the nest
from predators and other males while the female lays her eggs in long rows, forming
a solid, uniform mass of eggs in a single layer. The eggs are demersal (adhere to
the substrate), and clutch size varies from 200 to 2500 eggs depending on the species.
Polygyny is common: one male may guard the eggs of several females, and damselfish
harems have also been observed. Some damselfish are promiscuous, and still others
are monogamous. Polyandry has been reported only in an anemonefish, although monogamy
is the general rule for anemonefishes (
Amphiprion
and
Premnas
). These fish stay paired for at least a year and sometimes for their entire lifetime.
They spawn year-round, usually near the full moon. Hypotheses suggest that lunar
spawning occurs because of the increased light for nest tending, the greater currents
for larvae dispersal, and the relative abundance of spawning invertebrates as a food
source. Anemonefish most frequently live in single pairs, along with a group of sexually
immature individuals, in association with an anemone (see Reproduction: Mating Systems).
Groups containing several males and females may occasionally occur if the fish population
density is extremely high. Spawning occurs at the base of the anemone, on a rock
surface, or, if the anemone lives on sand, on a surface the fish drag near the anemone.
The male clears the nest site by biting at the tentacles of the anemone until they
withdraw, and then leads the female there for spawning, during which both fish quiver
and bite the nest surface.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sequential hermaphrodite
- sexual
- fertilization
- oviparous
Male damselfishes (and in very few cases, females) guard their eggs until they hatch.
They remove detritus, sand, and fungus-afflicted eggs, fan the eggs, and guard against
predators. Most become more aggressive when egg-tending, but this is not the case
with anemonefishes (
Amphiprion
and
Premnas
). In general fry are left to care for themselves after hatching, but in one Indo-Pacific
species,
Acanthochromis polyacanthus
, parents guard their school of young near the spawning cave for three to six weeks.
- Parental Investment
- male parental care
- female parental care
Lifespan/Longevity
Little is known about the lifespan of damselfish, but
Eupomacentris
spp. live an estimated six to eight years. Some species may live 10 to 12 years
in the wild and perhaps 18 years in captivity.
Behavior
Most pomacentrids, or damselfishes, stake out territories on patches of reef in sheltered
areas where they hide, feed and spawn. Males aggressively defend these territories,
allowing thick algal growth that provides them a primary food source. Sometimes females
have territories near the males. Relations between damselfishes and other fishes are
not always agonistic, as juveniles of some species of damselfish clean other fishes.
Certain groups of damselfish are not territorial; midwater plankton-feeders may have
shelter for retreat or spawning but do not maintain permanent territories, and anemones
provide a built-in defense for areas occupied by anemonefishes (
Amphiprion
and
Premnas
). Anemonefishes, however, may compete for position in the mating dominance hierarchy,
and have been observed striking each other with the pectoral fins. In the anemonefish
genus
Amphiprion
each group contains a male/female pair whose behavioral dominance suppresses the
sexual maturation of the smaller males. If one of the dominant fishes dies, the next
fish in the hierarchy takes its place (see Reproduction: Mating Systems).
Anemonefishes, comprised by the genera
Amphiprion
and
Premnas
, have a highly evolved relationship with sea anemones. They remain undisturbed by
contact with anemone tentacles that would be fatal to other small fish. A mucous
secretion is thought to protect them from the stinging nematocysts. While anemonefishes
receive protection living in close proximity with their hosts, the anemones benefit
as well. The fish clean the anemone’s upper surface, remove parasites, drop food
on the anemone, and chase away butterflyfishes that eat anemones. Waste excretions
from the fish may also help symbiotic algae within the anemone to grow. Anemonefishes
spend their entire adult lives with a single host.
- Key Behaviors
- natatorial
- diurnal
- motile
- territorial
- social
- dominance hierarchies
Communication and Perception
Damselfishes (Pomacentridae) use a variety of visual, olfactory, tactile, and auditory
cues to communicate in different situations. During courtship damselfishes respond
to the sight of spawning colors and ritualized movements performed by a potential
mate (see Reproduction: Mating Systems). Such movements may also signal the location
of territory to other males or encourage reproductive synchrony. Anemonefishes (
Amphiprion
and
Premnas
) appear to use perception of individual color differences to recognize their monogamous
partner. In addition to visual cues, male damselfishes use sound to ward off other
males and sometimes as part of courtship and spawning rituals. They may touch and
nip females to guide them toward a nest. Chemical cues from some damselfishes may
encourage conspecific (individuals of the same species) juveniles to establish nearby
territories and may discourage other groups of damselfish from settling. Young anemonefishes
use visual and chemical cues when choosing a preferred species of anemone as host.
Food Habits
Bottom-dwelling damselfishes feed, for the most part, on algae and small invertebrates.
They may tend “gardens” of filamentous algae, or in the case of anemonefishes, feed
on the anemone itself or other organisms that are commensal with the anemone. One
species of damselfish,
Cheiloprion labiatus
, or
largelipped puller
, eats the polyps of live coral. Damselfishes that live in the water column tend
to feed on plankton and zooplankton.
- Primary Diet
-
carnivore
- eats non-insect arthropods
- herbivore
- omnivore
- planktivore
Predation
Reef damselfishes gain protection from predators by hiding in coral shelters, anemonefishes
by living in close contact with a host anemone, and the free-swimming damselfishes
by schooling. Each group’s method of protecting itself applies to its eggs as well,
except for midwater damselfishes, which must establish temporary shelter for spawning
and egg laying.
Ecosystem Roles
Damselfishes are numerous and common on tropical reefs, and as such are an established
element of those habitats. Many of them affect the growth of algae on the reef, encouraging
algal growth in some areas while using the algae as a food source. The anemonefishes
provide some protection and bring in sources of nourishment for their anemone hosts,
and some groups of juvenile damselfishes clean other fishes.
Economic Importance for Humans: Positive
Many damselfishes are brilliantly colored and are popular aquarium fish. In aquarium
settings they can be aggressive, but are extremely hardy. In some areas bordering
the Indian Ocean people eat damselfishes that they catch in traps or with hooks, but
in general pomacentrids are not used for food.
Economic Importance for Humans: Negative
No specific information was found concerning any negative impacts to humans.
Conservation Status
Three pomacentrid species,
Chromis sanctaehelenae
,
Stegastes sanctaehelenae
, and
Stegastes sanctipauli
, are listed as vulnerable.
Other Comments
There are fossil records of pomacentrids from the lower Tertiary and lower Eocene
periods.
Additional Links
Contributors
Monica Weinheimer (author), Animal Diversity Web.
- oriental
-
found in the oriental region of the world. In other words, India and southeast Asia.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Australian
-
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- oceanic islands
-
islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Atlantic Ocean
-
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Pacific Ocean
-
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.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- cosmopolitan
-
having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- benthic
-
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
- reef
-
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.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- brackish water
-
areas with salty water, usually in coastal marshes and estuaries.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- bilateral symmetry
-
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.
- monogamous
-
Having one mate at a time.
- polyandrous
-
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
- polygynous
-
having more than one female as a mate at one time
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- iteroparous
-
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).
- seasonal breeding
-
breeding is confined to a particular season
- year-round breeding
-
breeding takes place throughout the year
- protandrous
-
condition of hermaphroditic animals (and plants) in which the male organs and their products appear before the female organs and their products
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- male parental care
-
parental care is carried out by males
- female parental care
-
parental care is carried out by females
- natatorial
-
specialized for swimming
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- territorial
-
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
- social
-
associates with others of its species; forms social groups.
- dominance hierarchies
-
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- pet trade
-
the business of buying and selling animals for people to keep in their homes as pets.
- food
-
A substance that provides both nutrients and energy to a living thing.
- carnivore
-
an animal that mainly eats meat
- herbivore
-
An animal that eats mainly plants or parts of plants.
- omnivore
-
an animal that mainly eats all kinds of things, including plants and animals
- planktivore
-
an animal that mainly eats plankton
References
Allen, G. 1998. Damselfishes. Pp. 205-208 in The World Encyclopedia of Fishes - second edition . San Diego, CA: Academic Press.
Berg, L. 1958. System Der Rezenten und Fossilen Fischartigen und Fische . Berlin: VEB Deutscher Verlag der Wissenschaften.
Böhlke, J., C. Chaplin. 1994. Fishes of the Bahamas and Adjacent Tropical Waters . Wynnewood, Pa: Published for the Academy of Natural Sciences of Philadelphia by Livingston.
Froese, R., D. Pauly, D. Woodland. 2003. "Fish Base" (On-line). FishBase World Wide Web. Accessed August 05, 2003 at http://www.fishbase.org/ .
Harmelin-Vivien, M. 2002. Energetics and Fish Diversity on Coral Reefs. Pp. 268 in San Diego, CA: Academic Press.
Helfman, G., B. Collete, D. Facey. 1997. The Diversity of Fishes . Malden, MA: Blackwell.
Hixon, M., M. Webster. 2002. Density Dependence in Reef Fish Populations. Pp. 314 in Coral Reef Fishes: Dynamics and Diversity in a Complex Ecosystem . San Diego, CA: Academic Press.
Hoese, D., R. Moore. 1998. Fishes of the Gulf of Mexico: Texas, Louisiana, and adjacent waters – second edition . College Station, TX: Texas A&M University Press.
Moyle, P., J. Cech. 2000. Fishes: An Introduction to Ichthyology – fourth edition . Upper Saddle River, NJ: Prentice-Hall.
Myrberg, A., L. Fuiman. 2002. The Sensory World of Coral Reef Fishes. Pp. 146 in Coral Reef Fishes: Dynamics and Diversity in a Complex Ecosystem . San Diego, CA: Academic Press.
Nelson, J. 1994. Fishes of the World – third edition . New York, NY: John Wiley and Sons.
Peterson, C., R. Warner. 2002. The Ecological Context of Reproductive Behavior. Pp. 103 in Coral Reef Fishes: Dynamics and Diversity in a Complex Ecosystem . San Diego, CA: Academic Press.
The World Conservation Union, 2002. "IUCN 2002" (On-line). 2002 IUCN Red List of Threatened Species. Accessed August 02, 2003 at http://www.iucnredlist.org/ .
Thresher, R. 1984. Reproduction in Reef Fishes . Neptune City, NJ: T.F.H. Publications.
Wheeler, A. 1985. The World Encyclopedia of Fishes - second edition . London: Macdonald.