ThRoewer
Guest
The common assumption that all Anemonefish start out as males is funamentally incorrect.
They rather start out as non-functional females, then, when rising to the number 2 position in the hierarchy, become functional males, and finally, if making it all the way to the top, become functional females.
So in general, there is only one mature functional male and one mature functional female in an anemonefish group, all the other are immature females, not males.
www.sciencedirect.com
"...
Male-to-female adult sex change is termed protandry and is seen in several families of fishes. Socially controlled protandry is best described in the anemonefishes, an Indo-Pacific group of 26 species ... The anemonefishes have been an object of fascination due to both the symbiotic relationship they show with large tropical sea anemones and their recognition as stars in the movie Finding Nemo that featured Nemo, a ‘boy’ anemonefish, being raised by his single father Marvin. However, had the movie been biologically accurate, Nemo’s father would have likely changed sex to become female following the disappearance of Nemo’s mother and Nemo would have been like other anemonefishes, developing as an immature female who would likely have matured into a functional male to form a breeding pair in the social group (Figure 1). This pattern of a breeding pair and up to several immature females forming social groups has now been described for several anemonefish species. The gonadal structure of males consists of peripheral active spermatogenic tissues surrounding immature ovarian tissue (oocytes in the previtellogenic stage of development, Figure 2). This pattern is interesting because it illustrates the fundamentally female-first pattern of development in sex changing fishes even when the adult sex change pattern is male-to-female (we can only speculate as to why the movie makers decided not to have Nemo’s father change sex!).
Figure 1. Sex change patterns in fishes.
Modified from Godwin J (2010) Neuroendocrinology of sexual plasticity in teleost fishes. Frontiers in Neuroendocrinology 31(2), 203–216
Figure 2. Gonad structure in the anemonefish Amphiprion melanopus for juvenile nonbreeders (a), breeding males (b), breeding females (c), and a sex changing fish 10 days after removal of the dominant female ((d) – low magnification, (e) – higher magnification). Abbreviations: EV, early vitellogenic oocyte; GL, gonadal lumen; PO, previtellogenic oocyte; SP, spermatogenic tissue (multiple stages); SZ, spermatozoa; OO, presumptive oogonia appearing as ovary develops during sex change. Scale bars = 100 mm.
Reproduced from Godwin J (1994) Histological aspects of protandrous sex-change in the anemonefish Amphiprion melanopus (Pomacentridae, Teleostei). Journal of Zoology 232: 199–213.
The maturation of juveniles and sex change by breeding males appears to be prevented by aggressive dominance of large females in anemonefishes. In the cinnamon anemonefish, Amphiprion melanopus, dominant females rapidly and aggressively approach their male pair mates approximately 150 times a day. Disappearance or experimental removal of these females eliminates this inhibition and both the behavior and gonadal structure of the male begin to change rapidly. Male cinnamon anemonefish made experimentally dominant show significant increases in aggressive behavior within 1 day of the removal of their dominant female pair mates and extensive changes in gonadal structure with proliferation of oogonial-like cells by 10 days later. Replacement of spermatogenic tissue with ovarian tissue is complete by 20 days.
..."
(bolding added)
They rather start out as non-functional females, then, when rising to the number 2 position in the hierarchy, become functional males, and finally, if making it all the way to the top, become functional females.
So in general, there is only one mature functional male and one mature functional female in an anemonefish group, all the other are immature females, not males.
SOCIAL AND REPRODUCTIVE BEHAVIORS | Socially Controlled Sex Change in Fishes
SOCIAL AND REPRODUCTIVE BEHAVIORS | Socially Controlled Sex Change in Fishes
Socially controlled sex change in fishes represents an extreme, but useful example of the very general phenomenon of environmental control of reproduc…
www.sciencedirect.com
"...
Male-to-female adult sex change is termed protandry and is seen in several families of fishes. Socially controlled protandry is best described in the anemonefishes, an Indo-Pacific group of 26 species ... The anemonefishes have been an object of fascination due to both the symbiotic relationship they show with large tropical sea anemones and their recognition as stars in the movie Finding Nemo that featured Nemo, a ‘boy’ anemonefish, being raised by his single father Marvin. However, had the movie been biologically accurate, Nemo’s father would have likely changed sex to become female following the disappearance of Nemo’s mother and Nemo would have been like other anemonefishes, developing as an immature female who would likely have matured into a functional male to form a breeding pair in the social group (Figure 1). This pattern of a breeding pair and up to several immature females forming social groups has now been described for several anemonefish species. The gonadal structure of males consists of peripheral active spermatogenic tissues surrounding immature ovarian tissue (oocytes in the previtellogenic stage of development, Figure 2). This pattern is interesting because it illustrates the fundamentally female-first pattern of development in sex changing fishes even when the adult sex change pattern is male-to-female (we can only speculate as to why the movie makers decided not to have Nemo’s father change sex!).
Figure 1. Sex change patterns in fishes.
Modified from Godwin J (2010) Neuroendocrinology of sexual plasticity in teleost fishes. Frontiers in Neuroendocrinology 31(2), 203–216
Figure 2. Gonad structure in the anemonefish Amphiprion melanopus for juvenile nonbreeders (a), breeding males (b), breeding females (c), and a sex changing fish 10 days after removal of the dominant female ((d) – low magnification, (e) – higher magnification). Abbreviations: EV, early vitellogenic oocyte; GL, gonadal lumen; PO, previtellogenic oocyte; SP, spermatogenic tissue (multiple stages); SZ, spermatozoa; OO, presumptive oogonia appearing as ovary develops during sex change. Scale bars = 100 mm.
Reproduced from Godwin J (1994) Histological aspects of protandrous sex-change in the anemonefish Amphiprion melanopus (Pomacentridae, Teleostei). Journal of Zoology 232: 199–213.
The maturation of juveniles and sex change by breeding males appears to be prevented by aggressive dominance of large females in anemonefishes. In the cinnamon anemonefish, Amphiprion melanopus, dominant females rapidly and aggressively approach their male pair mates approximately 150 times a day. Disappearance or experimental removal of these females eliminates this inhibition and both the behavior and gonadal structure of the male begin to change rapidly. Male cinnamon anemonefish made experimentally dominant show significant increases in aggressive behavior within 1 day of the removal of their dominant female pair mates and extensive changes in gonadal structure with proliferation of oogonial-like cells by 10 days later. Replacement of spermatogenic tissue with ovarian tissue is complete by 20 days.
..."
(bolding added)
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