December 2, 2021

I, Science

The science magazine of Imperial College

Cheyenne McCray brings us the five weirdest lovers of the animal kingdom...

Everyone knows the porcupine joke. But sexual attraction and reproductive behaviors in the animal kingdom are initiated across a wide spectrum. For some humans, it starts with ‘Netflix and chill’. For some animals, it’s  penis fencing and urine spraying…

African cichlids
Sexy seizures

1.African Cichlids

African cichlid fish mate via ‘mouthbrooding’, which refers to the incubation of fertilised eggs within the mouth of the female cichlid. But how does fertilisation occur? It involves some dancing and a rather appealing posterior! The mating process begins when a male attracts a female through a ‘dance’ made up of seizure-like motions. If she is interested, the two will swim over to a flat rock surface (the spawning area) and swim in circles for what can last hours. Eventually, the enticed female will lay her eggs and quickly scoop them into her mouth, unfertilized. This is where the appealing posterior comes in. The male cichlid’s anus is patterned to look like the eggs of the female. Believing them to be just that, the female cichlid will attempt to collect the ‘eggs’ off of the male’s anus. With her mouth left wide open, the male cichlid then fertilizes the eggs resting in her mouth.

Not your obvious penis-fencer.


Flatworms are hermaphrodites, meaning they have both sperm-producing testes as well as egg-producing ovaries. How do they mate you ask? Through ‘penis fencing’ of course. Penis fencing is a mating behavior that involves two flatworms attempting to stab one another using their dagger-like penises. Each penis consists of two sharply pointed heads which extend from the flatworms’ bodies, ready for ‘battle’. When a flatworm successfully stabs its opponent, it injects sperm directly into the others haemocoel (main body cavity). This is known as traumatic insemination. The flatworm that is successfully stabbed becomes the ‘female’, responsible for laying eggs.

Don’t stand underneath the females.


Preferring to live in solitude, female porcupines are indifferent to male porcupines for most of the year. When mating season commences, however, the female porcupine has a special way of showing her interest: watersports. The female will sit high in a tree, urinate, and then rub her genitals on nearby objects. Attracted to the pheromones present in the odor of the female’s urine, the male porcupine will climb the female’s tree. Sitting below the female on a lower branch for some time, the male will fight off other male suitors who may also have been attracted by her urine. Eventually, when he feels the time is right, the male will make his move by climbing next to the female and urinating on her. This act helps trigger the female porcupine’s breeding cycle. Once this is done, they descend from the tree and mate on the ground.

bowerbird with blue feathers scattered
Keeping a tidy home.


Found in New Guinea and Australia, female Bowerbirds choose their mating partners based on appearance. Not the physical appearance of the male Bowerbird himself, but rather the collection of objects he surrounds himself with. Male Bowerbirds spend countless hours building elaborate bowers made from sticks, leaves, and a variety of brightly colored objects he collects such as flowers, pieces of glass, berries and even coins. He may even vividly decorate a path leading to his hut structure for the female’s visual approval. Upon bower completion, a female will visit, often greeted with a ‘dance’ performance from the male. But female Bowerbirds also ‘play the field’. During mating season, they will visit several bowers, only returning to the one they find most attractive for mating. If you like, you can watch their romantic behaviour here:

Antechinus in tree hole
The ‘Sting‘ of the tantric marsupial world.


Antechinus are small marsupials found in parts of Australia and New Guinea that most closely resemble a cartoon mouse. As Antechinus are semelparous, meaning they only live long enough to breed once, sex is literally a once in a lifetime experience. Well, not really once. While antechinus do die after mating season, during the (up to) 12 hour mating process males have nonstop sex through protracted copulation with multiple females. In order to achieve this feat, the male antechinus forgoes food and suppresses his immune system, using all free metabolic energy to mate. At the end of mating season, the successful males die having traded their well-being for a short-lived sex marathon.

Images: cichlid, Dariush M; flatworm, Kristina Vackova; porcupine,Holly Kuchera; bowerbird,BMJ; antechinus, Gypsytwitcher.

Cheyenne McCray is studying for an MSc in Science Communication