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Striped Dolphins
Striped dolphins have three types of bodies we say look like girl bodies, like boy bodies, and bodies that look like both!
The same is true of Bowhead Whales and Fin Whales.
Updated from: “All Genders Are Perfectly Natural” (K-5) poster by Reflection Press, from the Gender Now Coloring Book © 2011.
Kangaroos
Many Red and Gray Kangaroos, Euros, Tammar Wallabies, and Quokkas have bodies we say look like girl bodies, boy bodies, and bodies that look a little bit like both. In all their bodies, they have a pouch. That way, the Joey can ride in the mama or papa’s pouch. Baby kangaroos are called Joeys. Girl kangaroos often adopt another kangaroo’s baby, just like wolves, elephants, and fathead minnows do!
Caption: A quokka and a baby quokka in its pouch.
A wallaby sits alone in a clearing in the forest.
Updated from: “All Genders Are Perfectly Natural” (K-5) poster by Reflection Press, from the Gender Now Coloring Book © 2011.
White-Tailed Deer
The boy and girl White-Tailed Deer often look like each other, even though they act differently! These deer have 5 different bodies that have different mixes of boy and girl-looking parts, and how much they look like a boy or a girl’s. Black-Tailed, Red-Tailed, Swamp, Sika and Roe Deer, Moose and Elk all have more than just boy-looking and girl-looking bodies.
A roe deer in the snow.
An elk lifting its head in a dry field, while other elk eat with heads lowered.
Two sika deer, one standing, one sitting, in the woods.
A moose lies down in a field.
Updated from: “All Genders Are Perfectly Natural” (K-5) poster by Reflection Press, from the Gender Now Coloring Book © 2011.
Clownfish, a dolphin, a whale, and other fish swim over the title “Sex Diversity in Nature: A brief exploration of sex diversity in the natural world.”
The Queer Sex Ed Community Curriculum is an LGBTQ-led project that is developing inclusive, trauma-informed, and sex-positive resources for use with youth. Their resource library includes zines, posters, and training materials that you can implement in your classroom. Check out the awesome Sex Diversity in Nature Zine, as well as their zine on Deconstructing the Gender Binary.
All females have ovotestes (ovotestes are gonads containing both ovarian & testicular tissue) XX have ovotestes & make eggs and testosterone only, XY have testes only and make sperm only.
Image caption: A Spanish blind mole emerges from underneath a rock. Photo credit (C) Tiago Magalhães.
Most gender-gene committees, with or without the presence of SRY, pass a resolution creating only a testis in males and only an ovary in females. In some species, though, even this most elemental aspect of bodily gender has been given a different configuration.
Among Talpa occidentalis—another burrowing mammal, an old world mole from the Iberian peninsula—all females have ovotestes, gonads containing both ovarian and testicular tissue. The ovotestes occur at the site in the body where simple ovaries are found in other species.
Talpa XX individuals have ovotestes and make eggs in the ovarian part of their ovotests. They don’t make sperm, but they do have both sperm-related and egg-related ducts. The testicular part of these ovotestes secretes testosterone. XY individuals have testes only and make sperm.
R. Jiménez, M. Burgos, A. Sánchez, A. Sinclair, F. Alarcón, J. Marin, E. Ortega, and R.D. de la Guardia, 1993, Fertile females of the mole Talpa occidentalis are phynotypic intersexes with ovotestes, Development 118:1303-11.
Roughgarden p. 202
One sunfish species, the bluegill sunfish (Lepomis macrochirus), has been studied in detail at Lake Opinicon, Ontario, Canada, and at Lake Cazenovia, in upstate New York.
Spawning males consist of three distinct size/color classes, and together with females, fall into four morphological categories, corresponding to four distinct genders:
I think the author, Roughgarden, is using gender to mean that there’s no sexually reproductive distinguishing function, and the difference is strictly morphological and behavioral. This also makes me wonder if the testes are lighter in the small male bluegill sunfish, given that they occupy most of the body cavity but still only comprise 5% of the total body weight of the fish. I am assuming she assigns male and female based on gamete production (egg/sperm) and/or primary regulatory hormone status (progesterone/estrogen/testosterone).
Large male bluegill sunfish are very aggressive, even towards females in their own nest, and defend their nest every 3 minutes.
Females prefer prefer nests with large populations to protect from egg predators.
Image credit: ScienceSource
The yearly spawning episode lasts only one day. In preparation, large males aggressively stake out territories next to one another in aggregations of a hundred or more, called leks, along the bottom of the lake at a depth of 1 meter. Large males are called on to defend their space against neighbors about once every 3 minutes. Large males make nests for eggs in their territories by scooping out a depression in the mud with their tails. Females aggregate at the locales with many males and do not visit isolated or peripheral nests. Females prefer nests belonging to large aggregations because the presence of many males affords more protection from egg predators.
The large males are not Mr. Nice Guys. Their acts of aggression include biting, opercular spreading, lateral displays, tail beating, and chasing. Although primarily directed at intruding males, aggression sometimes is directed at a female in the territory—domestic violence, sunfish style. The male apparently tries to control the speed and timing at which a female lays eggs. Females simply leave if harassed too much in this way.
The females arrive in a school, and one by one they enter the territories of the large males. When a female arrives, a large male begins to swim in tight circles, with the female following. Every few seconds as the pair turns, the female rotates on her side, presses her genital pore against that of the large male, and releases eggs that the large male fertilizes. The egg release is visible as a horizontal dipping motion.
Female bluegill sunfish spawn in many nests that the large, aggressive males guard.
9% of fertilizations are by a neighboring large male who took a break from guarding.
A female may spawn in many nests. A large male accumulates up to thirty thousand eggs from various females during the one-day spawning episode. A female lays about twelve eggs at a time with her dipping motion, so this total egg accumulation involves some female laying in the nest about once every 30 seconds. The scene is fast. Still, large males somehow find the time to enter the nests of neighbors, and about 9% of the fertilizations in a nest are by a neighboring large male.
The more numerous small males quickly fertilize eggs in nests that aren’t their own.
The females only choose nests based on how many fish are around it for protection.
Meanwhile, the small males are active. They stay at the borders between territories of large males and in the periphery, often close to rocks or in vegetation. Eggs remain viable in lake water for about an hour and sperm for only a minute. When the female releases eggs, the small males dart in quickly to release sperm over the eggs and carry out their own fertilizations. The large males try to repel the small males from their territories, but the small males are more numerous than the large males—about 7 to 1 in shallow-water colonies. Chasing all these small males, as well as neighboring large males and the occasional predator, takes a large male away from fertilizing eggs being laid in his territory. In these circumstances, the females spawn readily with small males while the large male is busy with all his chasing.
There are more small males in shallow-water colonies than deep ones because there is more vegetation for cover. It is important to hide because predators—large mouth bass, small-mouth bass, and pike—lurk in the lake. Thus the ratio of small to large males depends on the surrounding environmental context. All in all, the small males seem to be the gender counterpart of silent bullfrogs, silent singing fish, jack and parr salmon, and antlerless male deer.
Medium males: the romantic wingman.
Medium males court with large males, then join them in the nest to mate with a female bluegill sunfish. Both drive away other fish and both mate with the same female.
The medium males—the third male gender—are really surprising. No one knows where the medium males live most of the time, but they may school with the females. A medium male approaches the territory of a large male from above in the water and descends without aggression or hesitation into the large male’s territory. The two males then begin a courtship turning that continues for as long as ten minutes. In the end, the medium male joins the large male, sharing the territory that the large male originally made and defends.
Although the medium male sometimes joins the large male before a female has arrived, more often the medium male joins after a female is already present. The large male makes little if any attempt to drive away the medium male, in contrast to the way the large male drives away small males that dart into the territory.When a female and two males are present, the three of them jointly carry out the courtship turning and mating. Typically, the medium male, who is smaller than the female, is sandwiched between the large male and the female while the [courtship] turning [ritual] takes place. As the female releases eggs, both males fertilize them.
The females mate with the large male and then leave without a three-way interaction.
Occasionally, two females may be within a large male’s territory at the same time. Although the large male mates with both females, the three do not participate in any common ritual similar to the three-way interaction of the female with a large and medium male.
After the day’s excitement is over, each large male remains in his territory for 8 to 10 days to guard the eggs. The large male repels nest predators. During this period he never leaves the nest to forage and loses body weight.
In all, 85% of spawning males are either small or medium, with the remaining 15% large males. Although in the minority, large males take part in most of the matings.
Among the large males, the reproductive skew is high and only some of the large males apparently survive the mutual aggression that is necessary to acquire a successful territory. The small and medium males obtain about 14% of the spawnings. Overall, 85% of the territories in which spawning occurs consist of 1 male within 1 female, 11% of 2 or more males and 1 female—usually a large male accompanied by a medium male—and 4% of 1 male and 2 females.
Developmentally, the small and medium males are one genotype, and the large males another. Individuals of the small male genotype transition from the small male gender into the medium male gender as they age, whereas individuals of the large male genotype are not reproductively active until they have attained the size and age fo the large male gender.
Instead of deceit theory or ungendered signaling, Roughgarden proposes a third interpretation:
Once the medium male is sandwiched between the large male and the female during their combined courtship turns, the medium male may protect the female from spawning harassment [from the aggressive large males] through his position between her and the large male.
Also, the medium male may have developed a relationship with the females while schooling with them, and thus able to vouch that the large male is safe.
I suggest that the feminine male is a “marriage broker” who helps initiate mating, and perhaps a “relationship counselor” who facilitates the mating process once the female has entered the larger male’s territory. This service is purchased by the large male from the small male with the currency of access to reproductive opportunity.
Sharing fertilization represents an incentive to stay, not theft...Nothing prevents animals from cooperating in bringing about a mating, as well as in caring for young after a mating...In view of the roles played by the three male genders, let’s agree to call the large male a ‘controller,’ the small male an ‘end-runner,’ and the medium male a ‘cooperator.’
References
For Lake Opinicon studies, see:
M.R. Gross, 1982, Sneakers, satellites and parentals: Polymorphic mating strategies in North American sunfishes, Z. Tierpsychol. 60:1-26.
M. R. Gross, 1991, Evolution of alternative reproductive strategies: Frequency-dependent sexual selection in male bluegill sunfish, Phil. Trans. R. Soc. Lond., ser. B, 332:59-66.
For Lake Cazenovia studies, see:
W.J. Dominey, 1980, Female mimicry in bluegill sunfish—a genetic polymorphism? Nature 284:546–48.
W.J. Dominey, 1981, Maintenance of female mimicry as a reproductive strategy in bluegill sunfish (Lepomis macrochirus), Environ. Biol. Fishes 6:59-64.
Gross, 1991, Evolution of alternative reproductive strategies.
Dominey, 1981, Maintenance of female mimicry as a reproductive strategy in bluegill sunfish.
Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. p. 78-81.
Bullfrogs (Rana catesbeiana) have two male genders that both mate with females.
Bullfrogs have two male genders that both mate with females:
(1) large males who call at night, giving bullfrogs their name, and
(2) small males who are silent.
Both are reproductively competent, and females mate with both. Silent males turn into calling males as they grow older. Male frogs in older species and males in many vertebrate groups aslo have to decide when to begin breeding—whether to wait until established enough to flaunt wealth and power, or to begin sooner with fewer resources but lots of charm.
Silent males turn into calling males as they grow older.
Both still mate with females regardless of silence.
Perhaps silent males should not be considered a different gender from calling males, but rather an early developmental stage of the same gender. Compare this case with others, though, and you may agree that it makes more sense to view males who mature from a silent stage into a calling stage as changing genders.
R.D. Howard, 1978,. The evolution of mating strategies in bullfrogs, Rana catesbeiana, Evolution 32: 859-71.
R.D. Howard, 1981, Sexual dimorphism in bullfrogs, Ecology 62:303-10.
R.D. Howard, 1984, Alternative mating behaviors in young male bullfrogs, Amer. Zool. 24:397-406.
Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. p. 76.
Life-long pair-bonded male-male couples of the species Cygnus atratus will raise an egg together donated by a female.
Male-male black swan parents are more successful.
80% of gay black swan couples successfully raise their young, but only 30% of straight swan couples successfully raise their young.
Black swans (Cygnus atratus) also form stable male-male pairs that last for many years. Gay swans may even raise offspring together as a couple. A female may temporarily associate with a male-male pair, mate with them, and leave her eggs with them.
By sharing the workload more equally, male-male parents access better nesting sites and territories than straight couples.
The male couple then parents the eggs and is reported to be more successful than a male-female couple because together they access better nesting sites and territories, sharing the workload more equally than between-sex couples.
A full 80-percent of the gay couples successfully fledge their young, compared with 30 percent for straight couples. (EN19)
(EN19) L.W. Braithwaite, 1981, Ecological studies of the black swan: III. Behavior and social organization, Australian Wildlife Research 8:135-46.
Citation: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. p. 136.
Update (5/24/23): Thanks to J. Boeheme at Science TV Australia for clarifying these papers are about black swans, not all swans.
All female hyenas have functional penises they use to mount & give birth.
Erect penises are a sign of submission in the matriarchal society of hyenas.
The female hyena without the erect penis is the dominant leader of the entire pack.
Editor’s note: Earlier, the author defines “penis” in this discussion as something the animal can pee through. —RXS
Intersex plumbing is found in ALL females of the spotted hyena (Crocuta crocuta) of Tanzania—in which the females have penises nearly indistinguishable from those of the males. (EN23)…The first scientific investigation in 1939 showed that a spotted hyena makes only one-size gamete throughout its life, either as an egg or sperm. (EN24) Thus these hyenas are not hermaphrodites. Rather, female spotted hyenas are intersexed, like some female bears.
Editor’s note: The term "hermaphrodite" is appropriate for referring to non-human animals with sex characteristics that do not fit typical binary notions of male or female bodies. For humans, “intersex” is the appropriate term—learn more here!(EN23) L. Frank, 1996, Female masculinization in the spotted hyena: Endocrinology, behavioral ecology, and evolution, pp. 78-131 in J. Gittleman, ed., Carnivore Behavior and Evolution, vol. 2, Cornell University Press; L. Frank, 1997, Evolution of genital masculinization: Why do female hyenas have such a large ‘penis’? Trends Ecol. Evol. 12:58-62.
(EN24) M. Harrison, 1939, Reproduction in the spotted hyena, Crocuta crocuta (Erxleben.), Phil. Trans. Roy. Soc. Lond., ser. B, 230-1-78.
The females have a phallus 90% as long and the same diameter as a male penis (yes, somebody measured, 171 millimeters long and 22 millimeters in diameter). The labia are fused to form a scrotum containing fat and connective tissue resembling testicles. The urogenital canal runs the length of the clitoris, rather than venting from below. The animal can pee with the organ, making it a penis. Completing the picture, the female penis contains erectile tissue (corpus spongiosum) that allows erections like those of a male penis.
A female spotted hyena mates and gives birth through her penile canal. When mating, a female retracts the penis on itself, ‘much like pushing up a shirtsleeve,’ and creates an opening into which the male inserts his own penis. The female’s penis is located in the same spot as the male’s penis, higher on the belly than the vagina in most mammals.
Therefore, the male must slide his rear under the female when mating so that his penis lines up with hers. During birth, the embryo traverses a long and narrow birth canal with a sharp bend in it. About 15% of the females die during their first birth, and they lose over 60% of their firstborn young. (EN 25) These obvious disadvantages lead us to question why female spotted hyenas have this penis instead of a clitoris.
(EN25) L. Frank and S. Glickman, 1994, Giving birth through a penile clitoris: Parturition and dystocia in the spotted hyena (Crocuta crocuta), J. Zoology London 206:525-31; L. Frank, M. Weldele, and S. Glickman, 1995, Masculinization costs in hyenas, Nature 377:584-85.
Female spotted hyenas have a dominance hierarchy, and the erect penis is a signal of submission. When two females interact with each other in a struggle for dominance, the one who wants to back down signals by erecting her penis. (EN26) No one knows why female hyenas evolved this method of signaling.
(EN26) M. East, H. Hofer, and W. Wickler, 1993, The erect “penis” is a flag of submission in a female-dominated society: Greetings in Serengeti spotted hyenas, Behav. Ecol. Sociobiol. 33:355-70; H. Hofer and M. East, 1995, Virilized sexual genitalia as adaptations of female spotted hyenas, Revue Suisse de Zoologie 102:895-906.
Erections occur in the “meeting ceremony” when animals greet after having been apart. The animals approach each other and stand alongside one another, head-to-tail, one or both lifting her hind leg to allow inspection of her erect penis. When only one member of a greeting pair displays an erection, she is normally the subordinate.
Each hyena puts her reproductive organs next to powerful jaws. Greetings between captive females that have been separated for a week are tense and frequently wind up in a fight that starts when one bites the genitals of the other, doing occasional damage to the reproductive capability of the injured party.
[This] social-inclusionary trait…allows a female hyena access to resources needed for reproduction and survival. If a female were not to participate in social interactions using her penis for signaling, she would not be able to function in hyena society and presumably would either die or fail to breed.
[Testosterone from elevated aggression in hyena society can’t develop] a full-fledged replica of male genital anatomy, complete with scrotal sacs and fat bodies resembling testicles. This structure can’t develop from a few extra splashes of testosterone in the blood.
Citation: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. pp. 138-39.
Bighorn Sheep
1. Males (rams) & females (ewes) live separately except during breeding season.
2. Females are only sexually active 3 days of the year! They refuse all other approaches the rest of the time.
The males (rams), with large thick horns that curl back from above the eye to behind the ear, weigh up to 300 pounds. Their macho appearance has become a symbol for many male athletic teams. The females (ewes) live separately from the males. The sexes associate only during the breeding season, called the rutting season, which extends from mid fall to early winter. A female is receptive for about three days, and will not allow herself to be mounted outside of these three days. (EN29)
(EN29 ) V. Geist (1971) Mountain Sheep: A Study in Behavior and Evolution, University of Chicago Press; J.T. Hogg (1984) Mating in bighorn sheep: Multiple creative male strategies, Science 225: 526-29; J.T. Hogg (1987) Intrasexual competition in and mate choice in rocky mountain bighorn sheep, Ethology 75: 119-44.
All male bighorn sheep that breed with female ewes also participate in homosexual courting & anal copulation.
The males have been described as “homosexual societies.” Almost all males participate in homosexual courting and copulation. Male-male courtship begins with a stylized approach, followed by genital licking and nuzzling, and often leads to anal intercourse in which one male, usually the larger, rears up on his hind legs and mounts the other. The mounted male arches his back, a posture known as lordosis, which is identical to how a female arches her back during heterosexual mating. The mounting male has an erect penis, makes anal penetration, and performs pelvic thrusts leading to ejaculation.
Source: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. pp. 137-38.
Four behavioral phenotypes have been described in domestic rams raised in all-male groups: female-oriented, male-oriented, bisexual, and asexual. To make behavioral assignments, rams are first given sexual performance tests, also known as serving capacity tests, to determine whether or not they are attracted to females and to get a measure of their sexual performance.
Source: Roselli, C. E., Reddy, R. C., & Kaufman, K. R. (2011). The development of male-oriented behavior in rams. Frontiers in neuroendocrinology, 32(2), 164–169. https://doi.org/10.1016/j.yfrne.2010.12.007.
Bighorn Sheep have 3 behavior-based genders & 2 body types:
1. Female-body ewes live separately from gay male rams and only accept mounting 3 days of the year.
2. Male-body rams live together separately from females and copulate anally with other male-body sheep most of the year.
3. Male-body rams that live with female-body ewes most of the year and refuse mounting by other male-body rams.
The few males who do not participate in homosexual activity…are identical in appearance to other males but behave quite differently. (EN30) They differ from [so-called] “normal males” by living with the ewes rather than joining all-male groups. These males do not dominate females, are less aggressive overall, and adopt a crouched, female urination posture. These males refuse mounting by other males. In physical appearance, including body size and horn development, these males are indistinguishable from other males.
(EN30) J. Berger. (1985) Instances of female-like behaviour in a male ungulate, Anim. Behav. 33:333-35.
Citation: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. pp. 137-38.
Species: Ovis canadiensis (wiki)
Range: North American (Rocky Mountains, Sierra Nevada, southwestern US, Mexico)