In a world where it can seem that nothing is built to last, here is a creature that takes disposability to eye-watering extremes.
Like most nudibranchs, Chromodoris reticulata is a simultaneous hermaphrodite. Copulation is a two-way affair, with each participant inserting its penis into its partner's vagina. But much less conventional is what they do with those penises once mating is all over: after a struggle to disentangle themselves, both partners shed and discard them.
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However, this obviously presents a problem if the nudibranch needs to mate again. Fortunately, an individual can grow another penis within 24 hours, rolling it out from an internal coiled reserve that contains enough for at least two replacements.
Substitutes are necessary because the penis is covered in backward-pointing spines - thought to scrape rival sperm out of the vagina - which can cause the organ to get jammed and damaged during separation. Disposability ensures that there's a working penis ready for next time. Definitely worthy of a place on our weirdest animal penises list
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Main image: Reticulated Chromodoris © Getty Images