Clownfish in its home anemone. Image credit: Viktor Nunes Peinemann.

The universe is not only queerer than we suppose, it is queerer than we can suppose.

 – John Haldane

FOR DECADES, SCIENTISTS have reported same-sex mating in animals. But what’s less widely known is that animals can also change sex, present as a different sex or possess the characteristics of two sexes at once. Queerness in the natural world is rife, and gender is far from binary. In fact, this queerness is essential to the survival of many species.

The argument against queerness within human society often relies on the notion that it’s not natural. But nature itself can settle that argument.

SCIENTISTS USE THE phrase ‘sequential hermaphroditism’ to describe the process by which an animal starts life as one sex and then, due to an environmental or behavioural change, transitions to another.

The colourful clownfish, for example, is a sequential hermaphrodite – while clownfish are all born male, they carry male and female sex organs, and the change from male to female is essential to the species’ strict social hierarchy. The female is at the top of this hierarchy and is the largest fish in a group. The largest male in the group accompanies her; together they make the breeding pair. The rest of the population are immature males or ‘sub-adults’. The second largest male is next in the clownfish hierarchy, and an orderly queue forms behind him, dictated by body size. When the female clownfish dies, the breeding male will transition into the next breeding female – a process that takes around forty-five days.

This sex change helps clownfish increase the survival of their offspring, and the breeding male plays a major role in this. ‘It’s the male who will tend to the eggs and make sure they’re oxygenated [and] not too hot,’ says Hugo Harrison, a senior lecturer at the University of Bristol who has studied clownfish for years. ‘They have to protect their eggs during the period whilst they hatch.’ Although Finding Nemo avoided the realities of clownfish sex changes, it did portray Nemo’s dad, Marlin, as a very hands-on father.  

‘Many fish change sex when it suits them,’ Harrison continues. ‘Some individuals change sex more than once; they can go back and forth depending on the species.’

In fact, it’s so common for fish species to change sex that there’s a special word for fish species that don’t: they’re called ‘gonochoristic’ (‘gono’ meaning sex organs and ‘choristic’ meaning separated). The common goldfish is one of these gonochoristic fish species.

Many species other than fish can also undergo sex transitions, including the central bearded dragon, green sea turtle embryos and marine snails such as limpets.

It’s fair to say that the human sex binary makes little sense in the animal kingdom.

THE WORD ‘HERMAPHRODITE’ was, until the early twenty-first century, inaccurately used to refer to people who identify as intersex. These days, scientists use it to describe animals that possess what we might consider intersex characteristics. The word comes from the Greek myth of Hermaphroditus, the half-male and half-female child of Hermes and Aphrodite.

Broadly speaking, there are two kinds of intersex animals. ‘A gynandromorph is an individual that has both male and female tissue within the same body,’ explains Josh Davis, an editor at the Natural History Museum in London and author of A Little Gay Natural History. ‘These are distinct from a hermaphrodite, which can produce either male or female sex cells at some point in their life.’ Gynandromorphs can be various combinations of male or female in any part of their body, whereas hermaphrodites are both male and female in just their sex organs.

A zebra finch first unlocked our understanding of gynandromorphs. The phenomenon is uncommon in this species, so when a team of researchers discovered a gynandromorph zebra finch in 2003, they examined the bird in its entirety. What they found was incredible: its entire body, including its brain, was split perfectly down the middle. Even its birdsong was different depending on the side of the brain in which it was produced.

Gynandromorphs are found across a huge range of species, including lobsters, spiders, wasps, reptiles and birds. ‘I wouldn’t say [gynandromorphy is] common, but I wouldn’t necessarily say it’s rare either,’ Davis says. Around one in every 10,000 butterflies, for example, is a gynandromorph.

Spotting a gynandromorph is easy in species that are sexually dimorphic, which is when the males and females look significantly different. According to Davis, males and females in some butterfly species have distinct wing shapes. This means a gynandromorph butterfly can have two very different wings, potentially making it difficult for them to fly or reproduce.

‘Gynandromorphs shows us that sex determination is nowhere near as clear cut as is often assumed, and that there’s a sort of complex dance between chromosomes, hormones and chance…it’s all very fluid in that sense,’ Davis says. Even though there’s no evolutionary benefit to being a gynandromorph, their rarity and beauty makes them a wonder of the natural world.

One third of all animal species (not including insects) are hermaphrodites, including fish, insects and barnacles; all 7,000 species of earthworm (including the giant Gippsland earthworm, which can grow to more than a metre long) possess both male and female sex organs. Hermaphroditic animals can thrive in environments where it’s difficult to find a mate or in small populations with a limited gene pool.

Intersex characteristics in the animal kingdom, just as in human society, manifest in all kinds of ways.

RUPAUL IS THE world’s most famous drag queen. So famous, in fact, that the Australian soldier fly, Opaluma rupaul, was named after them. The fly has a very shimmery, colourful carapace that’s reminiscent of Ru’s shimmery, colourful gowns. Much less famous than RuPaul, however, are the animals that present and perform as another gender.

Scientists use the terms ‘transsexual phenotype’ or ‘sexual mimicry’ to describe these phenomena. ‘Phenotype’ refers to an animal’s appearance, and ‘transsexual phenotype’ means that an animal presents as a different sex. Similarly, sexual mimicry refers to an animal that can temporarily or permanently mimic a different biological sex. One such animal is the cuttlefish, which has thousands of colour cells known as chromatophores in its skin. These chromatophores can expand and change colour whenever the cuttlefish desires, mostly for camouflage or mating purposes.

For the mourning cuttlefish, this colour-changing tactic is a way to ward off sexual rivals. Culum Brown, a professor of fish biology at Macquarie University, explains that when a rival male approaches another male cuttlefish who is courting a potential mate, the courting cuttlefish ‘would position themselves between the female and…the rival male [and] switch their display on the side facing the rival into a female pattern, while still doing the mating display on the other to the female they’re courting. It’s mesmerising.’

Brown points out that cuttlefish are not queer in their sexual preferences. Instead, he says, these cuttlefish use drag purely as a ‘strategy to deliberately mislead’.

Giant cuttlefish males can also change their colour and shape to assume a female appearance, just as a drag queen might do with a chest plate and some padding.

‘The cuttlefish’s capacity for different displays and changing the texture of their skin…is unbelievable,’ Brown says.

But these drag-like characteristics in animals are not limited to looks. Scorpion-fly males mimic female behaviour to trick other males into giving them prey, and male garter snakes can produce a female-specific pheromone to reduce their chance of being attacked by predators.

For many animals, presenting as a different sex is essential to reproduction and survival as well as being incredible to watch.

From sex-changing clownfish to intersex worms and drag-superstar cuttlefish, the world is queerer than we can suppose – full of queer wonders that are both beautiful to look at and essential to species’ ability to survive and thrive. We’d do well to remember that the same applies to human society.