kizha~~rabbit fish

Rabbitfish/Sinagid

Rabbitfish/Siganid

DiversitySiganus -genus name of Siganadae familytwo subgenera: 1. Siganus-22 species 2. Lo-5 speciesRabbitfishes -common name of Siganids -from their peaceful temperament -rounded blunt snout, and -rabbit like appearance of the jaws. They are important reef herbivores that browse individually or in schools over the reef or feed on plankton within the water column.

HabitatReefsshallow lagoonssea grasses or mangrove areas.They are rarely found in estuaries(only one species, Siganus vermiculatus, is truly estuarine)Some primarily estuarine species have been successfully introduced into freshwater lake and pond habitats as well.Habitat RegionsTropicalSaltwater or marineAquatic BiomesPelagicReefCoastalOther Habitat featuresEstuarineInterdital or Littoral

Physical Descriptionmany strong spines with venom glands in dorsal and anal fins that contain a painful toxin.Most siganids are countershaded, but some reef species, Siganus vulpinus, have coloration similar tobutterflyfishes. The teeth are compressed into a single row and asymmetrically bicuspid. The dorsal fin has 13 spines and 10 soft rays and the anal fin has 7 spines and 10 soft rays.There are 23 vertebrate and the maximum length is approximately 50 cm.

Developmentfirst: produce small adhesive egg sacs, which then become larvae.the larval stage is planktonic postlarval stage called the acronurus.acronurus stage the body is transparent and individuals remain pelagic for an extended period before settling into the adult habitat and rapidly changing into the juvenile form.There is considerable morphological difference between larvae and adults and current information suggests that males reach sexual maturity before females throughout the family.

school in small to large groupsReproductionbreaking off into pairs or small units after spawning beginsIndividual pairs or groups behave aggressively towards one anotherJust before gametes are released, most siganids move in a circular pattern and the males develop a marble color pattern.10Mating Systemmonogamouspolygynandrous (promiscuous)Before spawning, siganids migrate to traditional spawning areas, with the location varying among species. Spawning peaks in spring and early summer, and as with many other coastal species, siganids show a prominent lunar rhythm. Spawning usually takes place at night or early morning and coincides with outgoing tides. Siganid larvae also respond to the lunar cycle, as most appear inshore (after the initial pelagic stage) three to five days before the new moon.

Lifespan/LongevityGenerally, smaller reef fishes such as siganids live between three and five years.

BehaviorSiganids are commonly known as rabbitfishes partly because of their peaceful temperament. They are diurnal herbivores, hiding in reef crevices during nighttime and browsing over reefs to feed during the day. Some species school while others browse individually among corals.

Food HabitsMost siganids are herbivorous and feed on phytoplankton or attached algae.

PredationSiganids are most threatened by predation during the planktonic, larval stage and very few larvae survive. On reefs, where most siganids live, predation is the most important cause of death. The elaborate defenses in the form of poisonous spines are a testament to predation pressures. The sharp, strong spines are coated with a mucous mixed with venom and can inflict painful wounds. rabbitfishes lose their color at nightfall and may also change color if threatened.

Ecosystem RolesAll siganids are diurnal herbivores and fill the roles of grazer and planktivore. Herbivores are quite important for the reef because they keep thick mats of filamentous and leafy algae from smothering the corals. All siganids are diurnal herbivores and fill the roles of grazer and planktivore. Other siganids use the reef mainly for shelter but hover above it in brilliant, shifting shoals, while feeding on plankton.

Basic anatomy