WRASSES
LABRIDAE
Bluehead Wrasse
Thalassoma bifasciatum
    Ecological Descriptors
Habitat Size (cm) Diet Behaviour Sex 
Co, R 25 Pla (Wor, Cru, Mol, Cle) Sh, Ter PGH
 
 
General:
Most wrasses are protogynous hermaphrodites, with some Initial Phase (IP) females, turning into Terminal Phase (TP) males once they reach a certain size. Those individuals who remain female in TP, retain the markings of IP. Juveniles usually have the same colouration as IP females.

Description
:
Terminal phase of male:
Head blue, followed by two dark bars, separated by a white bar. Rear body yellowish, green to blue-green.
Initial, juvenile phases and terminal phase of female: Cannot be distinguished by the color pattern or size. They display three basic patterns, all with a white belly and a black spot behind the third ray of the dorsal fin that does not reach the base of the fin. They can change from one to the other pattern rapidly, with intermediate color patterns between:
a.
White vertical bars break the dark midbody stripe into series of rectangular blotches. Back yellowish to greenish or bluish.
b. Body with a solid
midbody stripe from the snout to the tail. When swimming over reefs, the back is usually yellow, when swimming over sand or rubble, the back is usually white.
c. Yellow head and body above the white belly, without a midbody stripe, but with
two squarish spots behind the eye.

Ecology
The young ones can be found everywhere in small schools on the reef, especially in shallow water. The larger males are more solitary and found to depths of 40 m. Forms aggregations on shallow reefs that feed on plankton, also eats benthic invertebrates, with the smaller juveniles often cleaning other fish. Small specimens are females, which change into males when growing.  Males larger than 7 cm display the characteristics of the terminal phase.

Life Cycle:
Reported age is 3 years.  Length at sex change has been reported at 8.3 cm. The largest TP males aggressively defend breeding sites and therefore gain exclusive access to females visiting the site, conversely, initial phase females or males have no territorial defense and are much less aggressive. Spawn at midday throughout the year, within a period of a few days during the full moon and to a lesser extent, new moon. During the mating period, the majority of males are located at the down-current end of the reef, where they attempt to mate with the arriving females.
Bluehead Wrasse TP Male
Bluehead Wrasse
Juvenile/ IP/ TP Female
Var "a"
Bluehead Wrasse TP Male
Bluehead Wrasse
Juvenile/ IP/ TP Female
Var "c"
Bluehead Wrasse
Juvenile/ IP/ TP Female
Var "b"
Bluehead Wrasse
Juvenile/ IP/ TP Female
Var "b"
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