Top 10 Weirdest Facts About Animal Sex Lives


Compared to the animal kingdom, humans have relatively boring sex lives. But perhaps that’s a good thing, because a lot of animals have extremely complicated mating rituals, as well as other defining sexual characteristics we probably don’t want any part of. Such as …

10. Some Beetles Only Have One Testicle


Three major groups of beetles, each of which is in the carabid family, have a unique feature among the animal kingdom: they are born with only one testicle. Most animals have a quality known as bilateral symmetry, which means each side of the body is sort of a mirror of the other.These bettles almost got it right, except for that whole “only one side has balls” part.

Originally discovered in 1825 by French naturalist Leon Dufour, scientists are unsure of why the phenomenon exists, but the prevailing theory is that the testicle was lost somewhere in the evolutionary chain and replaced with slightly larger accessory glands, which are responsible for the creation of most of their seminal fluid.

9. The Western Harvest Mouse Has a Gargantuan Penis


The Western harvest mouse is a relatively nondescript rodent — native to western North America, only 2 centimeters tall, and a body length of up to seven centimeters. Typical mousey stuff, really. However, nature provided them with one thing to brag about: they have the largest penis of any rodent, relative to body mass. The penis bone of the Western harvest mouse is between 7 and 8 millimeters long, making its penis up to 9% the length of its body. Scientists believe that the rodent has evolved this penis size because breeding is so competitive.

8. Artificially-Bred Turkeys Physically Cannot Mate


This is technically not a natural process, as it is strictly a result of selective breeding led by humans, which makes it the saddest fact on this list. Turkeys, especially popular with Americans, are picked for their large breasts and they have increased in size immensely since they were first feasted on. However, this has presented the turkeys with a problem they’re unable to overcome: the breasts make it impossible for mating to occur. Nearly 100% of all turkeys bred are artificially inseminated because the tom (male) is unable to mount the hen (female). This also leads to an increase in the use of antibiotics because of a lack of genetic diversity, since there are relatively few mating toms available to farmers.

7. The Red Velvet Mite Uses a Trail of Silk to Attract a Mate


Humans might use rose petals to lead their significant other to the bedroom, signifying they’re ready for action. The red velvet mite has a similar mating ritual, though it does have an important difference: the surprise at the end of the trail is a pile of semen. Called “love gardens” by scientists, they are a pile of stalks or small twigs, which are covered by the males. To attract the females to the pile, the males will leave sophisticated silken trails leading to the pile. If a female finds it, and is impressed by the male, she will sit on top of the pile, inseminating herself. However, if a rival male discovers it first, he will destroy it immediately. Men suck.

6. California Sea Hares Form Hermaphroditic Love Chains


The California sea hare is a species of sea slug and is hermaphroditic in nature, frequently switching its gender from male to female. When mating season commences, large groups will congregate on kelp beds and prepare to reproduce. In order to more easily facilitate insemination, they will form a love chain, a complicated scenario in which each sea hare takes on both male and female sexual behavior. Every sea hare will inseminate the one in front of it, and be inseminated by the one behind it. They usually just form single-file lines, but there have been example found where they form a circle, with each sea hare taking on both roles.

5. Fruit Flies Have Never-Ending Sperm


Not only are fruit flies annoying as hell, they’re more sexually impressive than you. For one thing, they have the longest sperm in the animal kingdom. Drosophila bifurca, a relatively small fruit fly, produces coiled sperm which, when stretched out, is 2.3 inches, more than 20 times the size of the fly’s body. Scientists attribute this quality to the fact that female drosophila bifurca have extremely long reproductive tracts, which are designed to encourage “sperm competition.”

To put that in perspective, their sperm is 1,000 times the length of human sperm. And for some potentially-impressive-but-more-likely-disgusting perspective: if human sperm possessed the same ratio, it would stretch to roughly 120 feet.

4. Banana Slugs Eat Each Other’s Penises


Banana slugs are another example of an hermaphroditic animal. In their case though, the most interesting (and horrifying) thing about their mating process takes place at the end of the ritual. Usually during copulation, the slugs will bite each other, a prelude to the conclusion. When they are finished, and can’t pull apart, the female will chew on the penis, and keep chewing until it’s completely removed. It may remain in her body for awhile though, inseminating her independently during a process called apophallation. Unfortunately for the male banana slugs, their penis will likely never grow back.

3. A Duck’s Vagina Can Block Sperm If The Female Wants It To


By now, it’s fairly common knowledge that male ducks have corkscrew-shaped penises, and female ducks have corresponding corkscrew-shaped vagina. However, in species of ducks where forced intercourse is common, evolution has taken a step forward to combat the aggressive males, who have gradually grown longer and longer penises. Female ducks have co-evolved specially designed vagina which can twisted in such a way to create so-called “dead-ends” inside. Thus, unwanted males are unable to get their penises to where they want, and mating does not occur. If a male gets the female’s permission ahead of time however, she will change her posture and make it easier for the male to enter, enabling procreation.

2. Bats’ Brains Shrink as Their Balls Grow


Bats are one of the largest groups of mammals, with nearly 1,000 different species identified so far, yet they all share one interesting characteristic. Researchers at Syracuse University discovered that when a bat’s testicles increased in size, its brain shrinks at a similar rate. In the more promiscuous of bats, the males tended to have larger testicles, presumably to let them have more sex. Consequently, their brains were relatively small when compared to their more monogamous brethren. Scientists believe the variance has to do with the fact that bats need to be extremely efficient with the energy that they have. A large brain is not as essential when there are so many females to mate with, and so few Jokers to deal with.

1. The Bushcricket’s Got the Biggest Balls of Them All


Relative to body size, the animal with the largest testicles is the tuberous bushcricket. In 2010, scientists discovered that it has testicles which account for up to 14% of its body weight. That would be like the average human male having 25-pound balls, if you wish to imagine such a thing. 14% is a rather large increase over the former title-holder, a species of fruit fly which was a downright puny 10% (Or 18-pound human balls, which really isn’t that bad.)

Researchers at the University of Derby believe that testicle size is crucial to the mating patterns of the tuberous bushcricket. They don’t believe the size plays a role in the fertilization of a single female, as a relatively small amount of sperm comes out during each mating session — rather, it allows the males to mate with as many females as possible.

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