All juvenile Anemonefish are females!

[ThRoewer]

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.

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)

 

[IKD]

Thanks for sharing!

 

[OrionN]

I think this issue/question is academic only and pretty non essential in term of practicality for us in keeping our fishes.

To ME clownfish are juveniles then males then females. Protandrous hermaphodites by definition

BTW, unkike worker ants, which are non sexually function females. Worker ants have genetic of a female ants but environment turn them into workers instead of queens. Juveniles clownfish have the genetic of of all clownfish which can be either male or females. Why do these scientists splitting hairs and call them nonfunctional females instead of juveniles or nonfunctional males?
A lot of chopped up fish to answer non essential question to me.

 

[Dania]

Learn something new everyday. I always thought they were males first then maybe female. Although I also agree with OrionN.

 

[Birdbrains?]

If you compare their use of hermaphrodism with the reproductive strategy of Rotifers, you will notice a certain difference of purpose in what we today see as sex.

Rotifers are all "females" and fertilise each other's eggs.

When one of these "female" rotifers become dominant, only then will it start to produce eggs that hatch into "male" rotifers.

The single purpose in life for the "male" rotifer, is to inactivate the eggs of other "female" rotifers. The eggs fertilised by "males" falls to the ocean floor instead of hatching and the dominant "female" rotifer can spread their own offspring with less competition.

Humans classify lots of things as "male or female" that are actually species that have evolved their own reproductive strategies long before evolution of, what we perceive as, sex differences. Clownfishes are ofc. hermaphrodites who possess "ovatestes" but the immature juvies are perceived as males because clownfish mature testes before maturing ovaries.

 

[Azedenkae]

If you compare their use of hermaphrodism with the reproductive strategy of Rotifers, you will notice a certain difference of purpose in what we today see as sex.

Rotifers are all "females" and fertilise each other's eggs.

When one of these "female" rotifers become dominant, only then will it start to produce eggs that hatch into "male" rotifers.

The single purpose in life for the "male" rotifer, is to inactivate the eggs of other "female" rotifers. The eggs fertilised by "males" falls to the ocean floor instead of hatching and the dominant "female" rotifer can spread their own offspring with less competition.

Humans classify lots of things as "male or female" that are actually species that have evolved their own reproductive strategies long before evolution of, what we perceive as, sex differences. Clownfishes are ofc. hermaphrodites who possess "ovatestes" but the immature juvies are perceived as males because clownfish mature testes before maturing ovaries.

This.

The book referenced by op goes out of its way to claim the 'female-first' nature of clownfish by saying that 'peripheral active spermatogenic tissues surrounding immature ovarian tissue', but that really does not point to anything aside from, clownfish at least prior to transitioning fully to females contain both male and female reproductive parts.

Indeed, most of literature actually just considers 'non-breeder' individuals to be neither male nor female (unsexed, etc.) at best, or just refer to them as undeveloped males at worse because yes indeed, in individuals that has yet to undergone any form of sex change, both types of reproductive organs are clearly present. So calling them 'female first' really has no basis. 'Male-first' at least has the basis of the first sex that the fish transitions into is male, then female.

Nothing new or strange really, unfortunately just a book trying to be 'smart'.

 

[ThRoewer]

The key point here is that juvenile Anemonefish are not males and that there is in general no such thing as a "clownfish harem". At best you have a reproductive pair and a bunch of immature and inhibited juveniles who just wait for one of the pair to kick it so that they can move up.

If you compare their use of hermaphrodism with the reproductive strategy of Rotifers, you will notice a certain difference of purpose in what we today see as sex.

Rotifers are all "females" and fertilise each other's eggs.

When one of these "female" rotifers become dominant, only then will it start to produce eggs that hatch into "male" rotifers.

The single purpose in life for the "male" rotifer, is to inactivate the eggs of other "female" rotifers. The eggs fertilised by "males" falls to the ocean floor instead of hatching and the dominant "female" rotifer can spread their own offspring with less competition.

Humans classify lots of things as "male or female" that are actually species that have evolved their own reproductive strategies long before evolution of, what we perceive as, sex differences. Clownfishes are ofc. hermaphrodites who possess "ovatestes" but the immature juvies are perceived as males because clownfish mature testes before maturing ovaries.

The above is grossly distorted if not completely inaccurate.

"Some species consist only of females that produce their daughters from unfertilized eggs, a type of reproduction called parthenogenesis. In other words, these parthenogenic species can develop from an unfertilized egg, asexually. Other species produce two kinds of eggs that develop by parthenogenesis: one kind forms females and the other kind develops into degenerate males that cannot even feed themselves (sexual dimorphism). These individuals copulate resulting in a fertilized egg developing within the rotifer. The males survive long enough to produce sperm that fertilize eggs, which then form resistant zygotes that can survive if the local water supply should dry up. The eggs are released and hatch in the water. If the egg develops in the summer, the egg may remain attached to the posterior end of the rotifer until hatching."
from https://ucmp.berkeley.edu/phyla/rotifera/rotifera.html

So female rotifers do not need any fertilization to produce eggs and the eggs that get fertilized males are not dead or deactivated in order to kick the competition out of the race but rather to create a durable backup to ensure the survival of the strain in case the water dries up for some time. There are still males and females in the "classical" roles but females can produce viable "clone eggs" that have the same genetic make-up as their mothers.
If anything, then this proves that female was the original sex and mal sex was just an evolutionary afterthought to add variety to the mix.

 

[Azedenkae]

The key point here is that juvenile Anemonefish are not males and that there is in general no such thing as a "clownfish harem". At best you have a reproductive pair and a bunch of immature and inhibited juveniles who just wait for one of the pair to kick it so that they can move up.

Yes, but juvenile anemonefish are not females either. There is no reason to call them 'female' when they are better referred to as 'unsexed' or similar.

 

[Birdbrains?]

The key point here is that juvenile Anemonefish are not males

Your claim was that the sexually immature fish are females. They are not and they are referred to as "males" because their species develop testes before developing ovaries.

that there is in general no such thing as a "clownfish harem".

You seem to misunderstand what a "harem" is, let me explain:

A harem is not a group of sexually active individuals who all sleep with the same alpha figure. A harem is a big household servant group who are enrolled into the household as adolescents and will never know any other life than the harem and most of the harem will never get to have sex, at all. The purpose of a harem is to isolate the members of the harem from society and keep them dedicated to servicing the alphas of the harem.

The above is grossly distorted if not completely inaccurate.

"Some species consist only of females that produce their daughters from unfertilized eggs, a type of reproduction called parthenogenesis. In other words, these parthenogenic species can develop from an unfertilized egg, asexually. Other species produce two kinds of eggs that develop by parthenogenesis: one kind forms females and the other kind develops into degenerate males that cannot even feed themselves (sexual dimorphism). These individuals copulate resulting in a fertilized egg developing within the rotifer. The males survive long enough to produce sperm that fertilize eggs, which then form resistant zygotes that can survive if the local water supply should dry up. The eggs are released and hatch in the water. If the egg develops in the summer, the egg may remain attached to the posterior end of the rotifer until hatching."
from https://ucmp.berkeley.edu/phyla/rotifera/rotifera.html

So female rotifers do not need any fertilization to produce eggs and the eggs that get fertilized males are not dead or deactivated in order to kick the competition out of the race but rather to create a durable backup to ensure the survival of the strain in case the water dries up for some time. There are still males and females in the "classical" roles but females can produce viable "clone eggs" that have the same genetic make-up as their mothers.
If anything, then this proves that female was the original sex and mal sex was just an evolutionary afterthought to add variety to the mix.

The key word in your quote is "some" rotifers use parthenogenesis ThRoewer. And it is completely well-known that inactivated rotifer eggs can hatch under the right circumstances. Rotifer reproductive pattern is a survival strategy, not a self destruct impulse. As you observed, it creates a backup - in case the reproductive >alphas< turn out not being evolutionary successful down the line.

I could easily have gone into more details about rotifers which are some of my favourite lower developed lifeforms but this is not a rotifer breeding hobby debate, just a response to your perception that genderless fish are female.

If anything, then this proves that female was the original sex and mal sex was just an evolutionary afterthought to add variety to the mix.

The point of my comment was that there is nothing that is "female" before the evolutionary survival strategy of actually dividing the reproductive function into two fixed roles.

Female and male biological differences are a later addition to what was at first simply "resproductive specimens" which had neither female nor male division. As we also see with the clownfish, which simply possess a single reproductive organ which adapts to the situation they are in. But the reason subdominant clownfish specimens are called (a harem of) males, is that the development of clownfish reproductive organs does not mature ovaries before the testes have matured. The testes are then reabsorbed into the ovatestes tissue, allowing for the final stage of their potential development into what is indeed classified as female sex. They are sequential hermaphrodites, under the right social circumstances they can become sexually mature, first as males, then as females. They cannot develop the other way around and they cannot go back once having matured female sexual organs.

Since many people prefer to see pets as "he" or "she", the classification of the subdominant members of a clownfish family unit is therefore that they are "male". I know other people who refer to the subdominant clowns as female because that better fits their own preferences for (human) gender roles but personally I do not care what people call their dogs, cats, birds, reptiles, pet spiders or their fish, I refer to animals as "it" nomatter what sex they have.

 

[jgirardnrg]

 

[tbrown]

I think this issue/question is academic only and pretty non essential in term of practicality for us in keeping our fishes.

To ME clownfish are juveniles then males then females. Protandrous hermaphodites by definition

BTW, unkike worker ants, which are non sexually function females. Worker ants have genetic of a female ants but environment turn them into workers instead of queens. Juveniles clownfish have the genetic of of all clownfish which can be either male or females. Why do these scientists splitting hairs and call them nonfunctional females instead of juveniles or nonfunctional males?
A lot of chopped up fish to answer non essential question to me.

+1! It's interesting though, why would a female become a male to potentially become a female later? And, why then would a mature female not "regress" back to a male once a larger or more dominant anemone fish was introduced? Not that it matters since the largest is the female, the next largest is the male, and the rest are sexually immature.

 

[Azedenkae]

+1! It's interesting though, why would a female become a male to potentially become a female later? And, why then would a mature female not "regress" back to a male once a larger or more dominant anemone fish was introduced? Not that it matters since the largest is the female, the next largest is the male, and the rest are sexually immature.

Well in this case juvenile clownfish are really not female. It sounds like the author(s) just want to make a controversial statement here, despite their own text not supporting it (reproductive organs of both sexes does not equate being female). I don't know why they would do it, but it is a book, so they can kinda do whatever they want.

This was published in 2011. Literature before and after that overwhelmingly refer to juvenile clownfish as males (initially), and then immature males, or better yet unsexed/sexually immature/undeveloped/hermaphrodite to be more precise, because there is no reason to refer to an individual with both sexual organs as one of either sexes.