Charles Darwin proposed that due to the ferocious competition amongst males to find a partner, some species have evolved into having more than one kind, or morph, of gender. To some alpha males this means that if you don’t look like a threat, you can go about your business…except your business might be with his missus. Here are 10 truly evolved animals who prove that, as Jeff Goldblum once told us, life finds a way.
10. Marsh Harriers
While some animals only mimic features of the opposite sex until they reach maturity, over 40% of male Marsh Harriers spend their entire lives sporting feathers that look like those of a female. These males are also around 30% smaller and lighter than territorial males. These female-looking males use their appearance to get intimately close with females, although ornithologists are not sure if this translates to them successfully mating. One “transgender” male did, however, try to mate with a female-looking decoy (placed by scientists to study harriers’ behavior). No word on whether the other harriers teased him about it.
Female-looking males are also less likely to be attacked by bigger males, and also refrain from fighting with each other. The only aggressive behaviors demonstrated are toward females, which might be a learned behavior from real females to protect their nests. There is, in other words, a huge evolutionary advantage to avoiding fights with bigger males while easily getting close to females.
9. Bluegill Sunfish
There are three kinds of male Bluegill Sunfish: Parentals, satellites, and sneakers. Parentals build nests, attract females, and care for the young. Satellites act and look like females, so much so that parentals will tolerate their presence during mating. While showing off his luscious curves, he’s actually releasing sperm that will mix with the parentals’.
Last but not least are the sneakers. The smallest in size, these males pretend to be young fish. They swim under the female during mating, also adding their sperm into the mix.
Even though the parentals have the lowest sperm density, their sperm has the greatest success at fertilizing eggs. They can, however, only do so when they are seven years old. Sneakers and satellites are capable of fertilizing eggs at age two, but their sperm has a lesser chance of success. Because of this contrary relationship between fertilization chance and age, all three types have a decent shot at becoming a father.
8. Red and Olive Colobus Monkeys
These Old World monkeys (tailed primates found in Asia and Africa) live in single-male dominated groups. When old enough, males are chased away to seek out other bachelors while females live with their mothers for life. However, when males find themselves in that awkward in-between stage, they swell around the anal area to mimic the appearance of a female’s genital swelling (signaling she’s ready to mate). This swelling ceases when the Olive Colobus reaches adulthood, but continues for the Red Colobus.
Instead of trying to confuse or evade ruling males when mating, this tactic is used to appease them. Dominant males won’t confuse them for females, but rather tolerate them after this submissive display. This display is also used as a social greeting in other Old World monkeys. Once their male genitalia becomes more prominent, they can make a quick getaway with their thumbless hands (‘Colobus’ means docked in Greek) that act like hooks around tree branches.
7. Giant Australian Cuttlefish
Cuttlefish are surely some of the most bizarre creatures alive. They have massive, doughnut-shaped brains, highly-developed eyes to avoid predators (even in low light), W-shaped pupils, and three hearts that pump blue blood through their nervous systems. Like other cephalopods (which means head-footed) such as squid and octopus, the Giant Cuttlefish is an expert at camouflage. It can change color instantly and even displays a sequence of moving colors along its side. Although its skin is smooth, it contains tiny muscles that allow the fish to imitate shapes like rocks and seaweed.
Male Cuttlefish outnumber females 11:1, which is a problem if you are the little guy. To get around this, these smaller ‘sneaker males’ imitate the muted coloring of a female to slip undetected into the dominant male’s territory. After mating, many males swim away and die (after all, they’re “Cuttlefish,” not “cuddle fish”). They probably do so with satisfied memories racing around and around their circular brains.
6. Western Side-Blotched Lizard
There are no less than three male morphs based on the lizard’s throat color and behavior. Males with orange throats are at the top of the pile: they’re dominant, the biggest in size, and not monogamous. Next up are the blue-throated males, which defend the ladies from yellow-throated males but high-tail it out of there when an orange male shows up. Smaller than orange males, blue-throated males help to defend each other from orange and yellow males, which helps to increase their numbers. Due to their lower testosterone levels, blue males form a close bond with a single female.
At the very bottom is the yellow-throated male: their colors are similar to that of the females, which enables them to sneak past orange-throated males and mate with their partners. In other words, orange trumps blue, blue trumps yellow, and yellow trumps orange. This paper-scissor-stone approach to mating ensures the survival of all three kinds of males.
5. Spotted Hyenas
It would be very easy to mistake a female spotted hyena for a male. They have roughly the same body size and both sexes appear to have testes and a penis. A female’s ‘penis’ even becomes erect when she’s reunited with familiar members of her group.
Looks can, however, be deceiving. The female’s ‘penis’ is actually an elongated clitoris, through which she urinates, has intercourse, and gives birth. Her ‘testes’ are sacks filled by fat and combinative tissue. Females and males still compare in size, even though hers is not the real deal, and sadly the males always come up short. Due to females being dominant, males can be seen bowing before her, rubbing their faces on her forelegs.
The female’s genitalia are all internal, so once she’s sure the male is properly terrified she would roll up her clitoris to grant him access. To make sure that the enormous clitoris-cycle continues, she pumps her cubs full of Androgen (a hormone that ensures male characteristics) during pregnancy.
4. Midshipman Fish
Midshipman fish can be found from California all the way north to Alaska. These remarkable creatures come standard with light-exuding organs (Photophores) to attract a meal. They have also been found to be the cause of depriving entire cities of sleep. To attract females, males make a humming noise that sounds like chanting monks. As the male try to out-hum each other, it gets loud. Really loud. People in Seattle have been awoken in the middle of the night, whereas residents of California couldn’t hear each other speak. On top of the humming, the males also grunt and growl to defend their territories.
Well, one kind of male does, anyway. Wait, what do we mean by that exactly? Midshipman males are “multi-gendered”. One kind of male makes a lot of noise to attract partners, whereas the other kind, ‘sneaker males’, are silent. The silent males sneak into the hummers’ nests and fertilize their eggs.
All midshipman fish also hear better during the summer than during the winter. Unfortunately for humans, it still sounds like the neighbors forgot to turn off their washing machine year-round.
3. The Bellbird
Homosexuality and bisexuality have been well documented across the animal kingdom. Although transgenderism has been observed in other birds, the New Zealand bellbird was never a part of that group. Until now.
Male bellbirds have dark feathers, whereas females have a white cheek stripe on one side. This specimen has both. Its calls are also sometimes male, and sometimes female (though much louder than other females). Even though the bird was born female (confirmed by DNA tests), it displays male behavior. This bellbird doesn’t flutter from flower to flower, but instead darts aggressively and with purpose, as if to protect its territory. Scientists are unsure of the bird’s sexual preference as it is yet to be observed during mating season.
Though some officials have concluded that the unusual male-female mix is due to a hormonal imbalance, other biologists and conservationists have not ruled out trauma or an unfinished moult. Whatever the cause, this exceptional bird really is one for the books.
The distinctive orange and white patterned fish, made famous by the film Finding Nemo, live within a strict societal pecking order. The group is dominated by a senior breeding female, followed by her subordinate male. The rest of the group do not breed, often for years on end (clownfish are born as undifferentiated hermaphrodites, but later all become male).
The hierarchy is so rigid that subordinate fish limit their body size to no more than 80% of the fish above it (or be rejected from the group). Once the breeding female dies, a position is left vacant in the ranking. Her submissive male will move up one notch and simply change his sex from male to female. The rest of the group will also move up one position and expand their body size accordingly.
This evolutionary trait has nothing to do with availability of food, but rather to maintain harmony within the group.
1. Red-sided Garter Snakes
Sexual mimicry (also known as animal transvestism) occurs throughout the animal world. While some animals mimic the behavior of the opposite sex, others mimic their physical appearance. Red-sided garter snakes are a good example of the former. The snakes are so named due to resembling “garters” that men wore to hold up their socks.
Garter snakes hibernate as a group, (often together with other snake species) with as many as eight thousand snakes in a communal den. Enjoy trying to shake that nightmare scenario, by the way. When assembling or emerging from their burrows, they have to spend the minimum amount of energy to find a partner to mate with. The downside is that many males will swarm a female in an attempt to mate (which also leads people to believe their houses are being overrun!).
To turn the odds in their favor, male garters will emit female pheromones to attract females. When swarmed by males, the deceiving snake will try to slip away to catch the female alone. Aside from breeding purposes, being swarmed means a lesser chance of being caught by a predator, and provides warmth.