50 Shades of Grunion Run

Grunion run along the CA coast. Photo credit: Haris Lakisic, Pepperdine.

Her skin shone silver in the moonlight, a flash against the dark beach. She knew he wanted her. She could see him struggling, desperately fighting his way toward her. She positioned herself perfectly, knowing the site of her bound body, restrained and prostrate in the sand would make him—would make of all them—quiver with excitement.  The first to reach her, he feverishly curled himself around her as the others closed in, forming their own half-circle embraces.  She strained with the effort, with the closeness of all those bodies squeezing against her, and yet, her arousal only climbed with the number of strong, sleek forms wrapping around her. 

But just when she thought she couldn’t take any more, just as the lack of oxygen began to make her head spin, she could feel their grips relax and the slow, sweet slide of their pleasure slipping down her body. Their desire to hold her vanished the moment their burden was unleashed. 

How quickly they relinquished their hold of her, turning tail and heading back into the night.  Alone, she struggled to free herself from her binds, now more treacherous than alluring.  She gasped for breath and with her last bit of energy tore free of the hold. Quickly, she too turned toward the water’s edge, catching the next wave back out to sea.  Her suitors long gone, she would never know their names, never recognize them, masked as they were by the shadow of night.  But back there on the beach, somewhere safely tucked down beneath a thousand grains of sand, their DNA mingled and mixed with her own.  Knowing this, she could swim at peace…until next month’s full moon cast it’s spell, luring her ashore once again.

And that, dear reader, is the cleaned up version.

It’s of one of the most heroic and extreme acts of sex the sea provides.  And it happens by the thousands, every year, along the southern coast of California all the way to Baja.  If you live there, right now, you may be able to catch the tail end of this event (and likely be one of the only tourists to recognize how friggin’ masochistic this behavior actually is). These sexual extremists are grunion, Spanish for “grunters”—their onomatopoeic namesake reflecting the raucous they make in their effort to reproduce on shore. Their mass beachings are  called the “grunion runs” and they happen a few days after the full moon in spring and summer.

Grunions are not alone in the category of marine life that comes ashore for sex.  Female sea turtles have to heave their heft up sandy slopes to lay their eggs and elephant seals haul out to hump it up. But as I’ve been purusing the literature about group sex in fish, thus far, these guys are the only fish I’ve found that seal the deal in the sand.  Please let me know if I am missing others.

And, true to the title of this post, the act of flinging oneself on shore isn’t all these fish do to get laid. The females take the whole suffocation fetish (fish can’t breathe while out of the water, remember) and throw a little beach-sand bondage into the mix.  Once on shore, she digs her tail into the soft sand, sinking herself deep down, up to her armpits (sometimes, a females whole head will go under).  With her head sticking straight out of the sand, she presents herself as one sexy beast. The males flap their way up slope (she is holding her breath this whole time, remember, and the girl did some digging!), circle themselves around her, and then use her side as a slide for their sperm.  Oozing all over her body, the slippery stuff makes it way down to the eggs she has deposited below.  The males then turn tail and head back to the water, leaving her to dig herself out (still holding her breath) and catch the next wave out to sea.

Why go through such effort? Why risk beach stranding? I’m still getting to the heart of the matter, but thus far, it seems as though the benefits are associated with higher fertilization rates—the result of 1) the eggs being contained in the sand and not dispersed into the big blue sea and 2) nearly direct deposit of sperm onto the eggs, something more difficult to achieve in water.

Why the group sex? Well, first, the conditions have to be right for the fish to get far enough ashore to lay the eggs and not have them washed right back out to sea, but have the eggs in the right spot to be carried back out to see once they are hatched.  The grunion have adapted to local tidal cycles exactly in order to perfect this timing. The moon cues this timing, so the whole population takes advantage at once.  Second, from the female’s perspective, by having multiple males wrap around her and deposit sperm all together, she increases the diversity of DNA that reaches her eggs. This ups the odds that among that mix of dads, there will be some really fit dudes to make up for any duds.

So, why do we need to know this? Well, for some, watching the grunion runs is quite the experience. It is a pretty spectacular visual, seeing thousands of silver shards flapping in the moonlight.  It also brings up the importance of protecting prime mating habitat. These fish depend on these beaches to support their sexual endeavors. As extreme as they are, they cannot overcome massive beach erosion due to poor land management, or disappearing beaches due to rising sea levels. For these fish, life literally is bound to beach.  To protect these kinky little silversides, and continue to watch them flaunt their stuff, requires we take action to protect the coastline they depend upon.

Check out this cool new documentary, Surf, Sand, and Silversides: The California Grunion for more info.

Stay tuned for more on oceanic orgies as I continue to research this chapter for my book! As always, comments welcomed!

2 thoughts on “50 Shades of Grunion Run

  1. [...] pillage of the mating masses for their sacred sangre adds insult to injury.  Like grunion in the previous post, they also suffer from threats to their shallow love nests such as sea level [...]

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>