Sea of (Unromantic) Love: Strange Mating Behaviours

Tired of being alone on Valentine’s Day? Well, picture yourself in any of the following scenarios and well, maybe it’s for the best. Yesterday, we learned about how the male anglerfish becomes a parasite. Here are a few more unromantic, and downright strange examples of ocean animal reproduction (from the human perspective of course).

The “Shot in the dark”


The oceanic squid (Octopoteuthis deletron) is usually solitary and has been found off the coast of California in Monterey Submarine Canyon at depths of 400-800m. While deep-sea squids generally have highly developed eyes, at this depth, they cannot rely on sunlight to visually find each other. Male and female oceanic squids are a similar size and shape, so it’s hard to tell each other apart, and the males don’t even seem to bother trying. Males indiscriminately mate with females and males. How do we know? Equal proportions of both male and females have been found with sperm sacs implanted in similar (and multiple!) places on the body. Males use their penis equivalent (terminal organ) to transfer spermatophores which break out into smaller sperm sacs that implant into the tissue. Since some of these places are beyond the reach of the terminal organ, accidental self-implantation is ruled out. Perhaps even stranger is that these squids have the capacity to produce light on the tips of their arms and change colour via overlying chromatophores to communicate their sex, but they don’t. However, considering their short life span, and the fact that they usually have but one window of opportunity to reproduce before death, these guys follow a reproductive strategy that pays off when they take a shot in the dark.

The golden shower

Imagine you’re sitting at your doorstep, and you see a cute member of the opposite sex strolling by. Do you:

A: Wink at them

B: Introduce yourself

C: Urinate in their face

Watch out! This lobster thinks you're cute. (Credit: Derek Keats, flickr Creative Commons).
Watch out! This lobster thinks you’re cute. (Credit: Derek Keats, flickr Creative Commons).

In the lobster’s (Homarus americanus) case–yes the steamed ones you crack open and bathe in butter on the East coast of North America–the answer is C. This species of lobster along with some others have glands on their face that release urine. “Oh dear god, why?!” you ask? Lobster urine is a vehicle for pheromones (chemicals that work outside the body to evoke a reaction from members of the same species). Female lobsters are typically the ones on the prowl, scuttling around ocean avenues, searching for and visiting multiple dens occupied by male prospects. When she wants to engage, usually with a dominant male, she urinates out of her face to present her pheromones, and when the male gets the signal, he lets her into his den. The female then gets naked—no really—she moults to make relevant parts available. Then the male climbs onto her back, flips her over and internally deposits a capsule of sperm. Interestingly, the sperm capsule or spermatophore hardens into a plug to deter insemination from other males—although this does not stop the female from mating again. As a gentleman wouldn’t kick a naked lady out of his house, the male protects the female for a few days as her new exoskeleton hardens.  They part ways just in time for another female to pee at him. Females can keep sperm for over a year from multiple males. Then, although sperm is deposited internally, actual fertilization occurs externally when the eggs are laid. Side note: if you think no self-respecting mammal would use urine for courtship, consider the moose and their scent marking.

Crossing Swords

Sea slugs don’t have the same problems that the squids above do. Most are simultaneous hermaphrodites, meaning they have both male and female reproductive organs. As you might have guessed, sea slug sex is sloppy at best.  With both male and female reproductive parts, sometimes they undergo peaceful cross-fertilization, other times, it’s a “hit and run”.  Considering this free-for-all, one can safely assume, they have a few tricks up their penises and female reproductive organs:

The Head Stab: An unidentified sea slug in the genus Siphopteron has a two-pronged, extendable and flexible penis. One part is the penile bulb that goes nicely into the respective female openings and transfers sperm. The other part is a ‘stylet’ or spine that gets stabbed just above their mate’s eyes. The stylet delivers prostate fluid that may target the central nervous system in the hopes to stop their mate from digesting their sperm. Oh yeah, they can do that too.

Elysia timida, back-stabbing sea slugs (Credit: Parent Géry)
Elysia timida, back-stabbing sea slugs (Credit: Parent Géry)

The Tit for Tat Back Stab: Elysia timida are also simultaneous hermaphrodites but instead of stabbing each other in the head, they stab and inject each other (perhaps with sperm, but this has not been confirmed) repeatedly in the back.  To do so, they evert their penises located under their right eye and stretch it 1/3 third of their body to reach their partner’s back.  They alternate back stabbing with harmonized circling movements up to 34 times before a final sperm transfer into the female opening.  Elysia timida is exceedingly cooperative, usually reciprocating whatever actions their partner take.


Chromodoris reticulata - a sea slug with a disposable penis (Credit: prilfish, flickr Creative Commons)
Chromodoris reticulata – a sea slug with a disposable penis (Credit: prilfish, flickr Creative Commons)

The Disposable Penis: After Chromodoris reticulata copulates, they cast off their penises.  While amputating a penis may seem like the end of a lineage, their penises are actually longer than they look and are sectioned. C. reticulata has enough length for two backup penis sections coiled up inside and ready to go in 24 hours. Oh, and their penises have backward pointing spines which may act to remove sperm already stored in their mates.

And there you have it, just a small sampling of the weird and wonderful ways marine animals get down. Know of any other sea creatures that get down in a strange way? Let us know what we missed!



Gosselin, T., Sainte-Marie, B., Bernatchez L., (2005). Geographic variation of multiple paternity in the American Lobster, Homarus americanus. Molecular Ecology. 14(5):1517-25. doi: 10.1111/j.1365-294X.2005.02498.x

Hoving, H., Bush, S., Robison, B., (2011). A shot in the dark: same-sex sexual behaviour in a deep-sea squid. Biology Letters., doi: 10.1098/rsbl.2011.0680

Lange, R., Werminghausen, J., Anthes, N,. (2013). Cephalo-traumatic secretion transfer in a hermaphrodite sea slug. Proceedings of the Royal Society. 281(1774). doi: 10.1098/rspb.2013.2424

Phillips, Bruce. Lobsters: Biology, Management, Aquaculture and Fisheries. John Wiley & Sons, 2008. Print.

Schmitt, V., Anthes, N., Michiels, N., (2007). Mating behaviour in the sea slug Elysia timida (Opisthobranch, Sacoglossa): hypodermic injection, sperm transfer and balanced reciprocity. Frontiers of Zoology. 4:17. doi:  10.1186/1742-9994-4-17

Sekizawa, A., Seki, S., Tokuzato, M., Shiga S., Nakashima, Y., (2013). Disposable penis and its replenishment in a simultaneous hermaphrodite. Biology Letters., 9(2). Doi: 10.1098/rsbl.2012.1150.

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