As humans, we have countless idiosyncrasies surrounding both our reproductive organs and our expression of our sexuality. But what about other animals? Some have unbelievable sexual characteristics! Here are my top picks from our animal kingdom:

Bonobos: A bonobo is a type of chimpanzee with a penchant for smiling. Bonobos are an endangered species currently living in the wild in the Democratic Republic of the Congo. As bonobos are the closest relative to humans still in existence, it shouldn’t come as too much of a surprise that these primates are the only non-humans that engage in tongue kissing and oral sex. But bonobos also engage in pretty much every type of partner combination possible when it comes to sexual intercourse: male-to-male, female-to-female, father-to-daughter and so on. Bonobos have sex very frequently between all members of their society.

Barnacles: Barnacles are those round-shaped, shell-like creatures one often observes affixed to rocky surfaces in and around the ocean. Related to both crabs and spiders, these crustaceans are typically hermaphroditic, containing both male and female parts within each individual barnacle. But not only do they have both sets of sex organs— which can release up to 10,000 larvae for fertilization by other barnacles—but they also have penises that can be up to eight times their body length. Having the longest penises for any creature of their small size, barnacles use these essential “sperm tubes” to reach as many other barnacles and their larvae as possible.

Pandas: These endangered black and white patterned bears are known worldwide for their poor genetics and reproductive difficulties. With a population of barely 1,500 in the wild and in captivity combined, pandas, in an almost human-like way, will mate only with co-eds that have personalities which mesh with their own. Even so, they would rather spend their day noshing on bamboo and lazing around than reproducing—a characteristic that only contributes to their endangered and shrinking population. To combat this, researchers have designed panda “sexercises,” which ABC News describes as “specialized exercises to strengthen the males’ hind legs and increase their stamina” and “panda porn” for the males to watch while in captivity to stimulate arousal. Interestingly, the combination of these methods has increased the percentage of pandas able to have sex on their own from 25 percent to 60 percent.

Orcas: Orcas, or killer whales (think “Free Willy”), mostly reproduce in a typical fashion, with males seeking multiple partners and females seeking one primary mate. But male orcas are known to have extremely large penises—relative to their size (and to the penises of the planet). The record length of an orca penis—and thus any penis—was measured at 8 feet!

Spiders: In some species of spiders, including the Australian redback, females dominate social and reproductive interactions, as they can be up to 50 times larger in size than their male counterparts. In the redback species, many males get eaten during mating, which the male sometimes actively assists by placing his abdomen over the female’s mouth to fertilize more eggs. Once the male’s sperm is obtained by the female spider, with or without sexual cannibalism, the female can store said sperm and use it for a period of up to two years to lay eggs.