Self-preservation is the most important thing in nature. To ensure their being on the earth some animals procreate in a very unusual way.  The curios sex organs range from multiple heads to massive shafts exceeding and animal own body length. These are the 10 of most unusual animal penises.

1. The fish with a penis on its head

Most animals have their reproductive organs located close to their tail-ends. But that’s not the case for a newly discovered species of river fish identified in Vietnam’s Mekong Delta. This fish penis is on her head.

2. The seat turtle

Male sea turtles are “horrifically” well-endowed, says Darren Naish at Scientific American. Softshell varieties like the leatherback have penises that, when erect, extend to nearly half the animal’s 8-foot body length.

3. The Argentine bluebird duck

Most male birds don’t have penises. But a few, such as the Argentine lake duck, more than make up for it. The duck’s penis is shaped like a corkscrew and can extend to more than 17 inches. (The bird is only 16 inches tall.)

4. The warehouse pirate bug

The tiny 3mm (0.11 inch) creature also practices one of the animal kingdom’s most dangerous copulation methods: Its spiny penis is razor-sharp, and instead of inseminating females by traditional means, the bug uses its sex organ to violently stab through her exoskeleton in order to ejaculate.

5. Dolphins

The dolphins have retractable penises that are kind of like multi-tools. Not only does the male dolphin’s penis swivel around, but it’s often also used to feel out other objects, kind of like a human hand.

6. Flatworms

Flatworms are hermaphrodites, meaning they have both male and female sex organs. The first to successfully impregnate the other while fending off advances becomes the de facto male, who wins because he won’t have to expend the energy required to carry eggs.

7. The echidna

The echidna, also known as the spiny anteater, is native to Australia and New Guinea. Like its cousin the platypus, echidna females lay eggs instead of giving birth like other mammals. Scientists, however, have long been perplexed by the male anteater’s mysterious sex organ, which secretes semen from four different heads. Getting all four of these into a female is impossible when fully engorged, so the echidna only insert two at any given time. Studies suggest that going halfsies may make the individual sperm swim faster.

8. The orb spider

Male orb spiders detach their penis and insert them in female spiders to impregnate them. Having penis-detached intercourse allows the male spiders to not only escape the hungry female — who successfully eats the male 75 percent of the time — but also gives them a better chance of fending off competing males.

9. The barnacle

barnacles actually possess one of the longest penises in the world — at least relative to their body size. The filament-like penis extending from its shell has an exoskeleton with “accordion-like folds” that stretch out to inseminate nearby females. Barnacles that live near shore breaks often develop thicker, heartier manparts to survive the crash of oncoming waves.

10. The argonaut octopus

Male argonauts are much smaller than females — only 3/4 of an inch versus a gal’s 4 inches. That’s why when attempting to mate, the dimunitive male argonaut octupus tries to maintain its distance, using a “special tentacle” that detaches from its body. The swimming penis squirms its way over to the female to deliver semen to her waiting eggs.