The parasite has somehow evolved to turn off the host's defenses, presumably by disarming the crab's immune response with some chemical trickery that fools the host into accepting the parasite as part of itself. ...The adult parasite castrates the host, not by directly eating the gonadal tissue, but by some unknown mechanism probably involving penetration of the interna's roots around and into the crab's nervous system.

The intricate and different life cycles of both male and female root-heads, and the great behavioral sophistication shown by the female in reconfiguring a host crab as a support system, all underscore the myopia of our conventional wisdom in regarding rhizocephalans as degenerate parasites because the adult anatomy of internal roots and external sac seem so simple.

Lernaeodiscus porcellanae turns control of the host into a fine art. After castration by the parasite, male crabs develop female characteristics in both anatomy and behavior, while females become even more feminized. The emerging externa then takes the same form and position as the crab's own egg mass... The crabs then treat the externa as their own brood. In other words, the parasite usurps all the complex care normally invested in the crab's own progeny.

There’s something called the Crab Effect. If you put a bunch of crabs in a bowl and if, while they’re in there crawling all over each other, one of them tries to climb out, the rest of them will try to pull him back down instead of helping to push him out. No wonder they’re called crabs. Imagine how different our world would be if we were less crab-like.

I am a hollow shell, the crab's died, there's nothing left inside. Don't they know that?

His sympathy (that is, for a caterpillar parasitized by a wasp) was an anthropomorphism, a projection. The caterpillar was hardly more than a protein engine enacting a suite of encoded behaviors. A meat robot. As am I, except that in the case of Ethan’s species evolution had conjured a knowing self out of chemistry and contingency. I feel, therefore I abhor.

Your Father Walks Like a Crab

(on cockroaches living without a head for a week) Why, when it was invented, has it got that facility?

One lies upturned on the sand. Its tail sake waggles feebly, quite unable to perform the task of turning the body back over again. Five paris of legs twitch ineffectually in a vain attempt to achieve the same end. I find it impossible to resist the temptation to right the poor animal. It is easy to grasp it by the edges of the head-shield. Once righted again those spindly legs allow the crab to trundle slowly away. Its behaviour seem at once strangely determined, but also apparently random, like the slow progress of a confused old lady on a .

You cannot teach a crab to walk straight.

The highest treason a crab can commit is to make a leap for the rim of the bucket.

"In Leonardo da Vinci's Notebooks, we read: "An oyster opens wide at full moon. When the crab sees this, it throws a pebble or a twig at the oyster to keep it from closing and thus have it to feed upon." Da Vinci adds the following suitable moral to this fable: "Like the mouth that, in telling its secret, places itself at the mercy of an indiscreet listener.

"The crab scuttled toward its hole. "Sacculina is a parasite that infests saltwater crabs. It burrows into their flesh and extends tendrils into the crab’s bloodstream and brain. It chemically castrates the crab and becomes its new brain — controlling it like a zombie.

This process is called artificial selection. In the case of the Heike crab it was effected more or less unconsciously by the fishermen, and certainly without any serious contemplation by the crabs. But humans have deliberately selected which plants and animals shall live and which shall die for thousands of years.