Parasite: A Love Story

Have you read The Things They Carried by Tim O’Brien? It’s an amazing book for a hundred reasons, but one thing that sticks in my mind is the way O’Brien describes love. (No, this isn’t going to be one of those kinds of posts; hang in there.) First, near the beginning of the book, when a soldier thinks about the girl he left at home:

[H]is love was too much for him, he felt paralyzed, he wanted to sleep inside her lungs and breathe her blood and be smothered.

Then in the final chapter, a first-person account of a childhood infatuation:

Even then, at nine years old, I wanted to live inside her body. I wanted to melt into her bones — that kind of love.

Seriously, he’s a damned good writer.

Anyway, most of us don’t actually get to inhabit the objects of our affection — except maybe figuratively, but where’s the fun in that? In the ocean, though, there’s one incurable romantic who’s got it all figured out:

(Hans Hillewaert, Wikimedia Commons)

Meet Sacculina.

Sacculina is actually a kind of barnacle, though it doesn’t look at all like the ones on the beach. As a pretty young female larva, it finds a good-looking crab and punctures its exoskeleton at a soft, bendy joint. Sacculina then injects itself into the crab’s body, growing into a balloon that sits in the abdomen. It extends long, nutrient-leeching tendrils into every corner of the crab, like this:

Into you like a barnacle, baby. (From Ernst Haeckel's "Kunstformen der Natur," 1904)

The parasite has so much control that eventually the crab stops growing, hunts down food for the barnacle’s benefit, and even — after the barnacle’s mate moves into its abdomen too — takes care of the resulting larvae as if they were its own. (Say it with me: Awwww.)

Okay, so maybe that’s not exactly what O’Brien meant. Maybe it’s not the most healthy, mutually respectful relationship in the world. But if nothing else, I bet that crab writes the best angsty love poems.


About Mara Grunbaum

Science reporter in New York City.
This entry was posted in Marine Science and tagged , , , , . Bookmark the permalink.

3 Responses to Parasite: A Love Story

  1. Will says:

    Is this a symbiotic relationship? I am amazed at how far the parasite travels in the crabs body, even taking control of the crab while not killing the crab. Very Interesting

    • maragrunbaum says:


      It’s symbiotic in that the two animals are closely associated with one another and one depends on the other to live, but it’s not a mutually beneficial symbiosis (like the one between large fish and little cleaner wrasses, for instance).

      The crab doesn’t die, but it doesn’t get to reproduce either, since the barnacle has hijacked its reproductive system. All in all, not a great deal for the crab.

  2. Christie says:

    Tim O’Brien is a great writer – loved that book. And Sacculina is a great parasite!

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