Neuropinion (English)

Free opinion about neurosciences

Friday, March 14, 2003

The Meta-consciousness of the Small Things

Example 1. Toxoplasma Gondii, a small parasit that damages the brain of fetuses, only can be developed in the cat. Strikingly, this apparently is "known" by the parasit. Lets see: in a given moment of its life Toxoplasma Gondii lives in the brain of rats which have an specific phobia to cats, even after several generations of laboratory reproduction. This, obviously points to a hardwire rather than a learned condition. Rats smell the pheromones of cat avoiding the territory of the feline. Well, the parasit has the ability to change that behavior. Rats infected with Toxoplasma Gondii do not avoid any more the cats having otherwise intact the rest of its natural preserving skills. In this manner the parasit "exposes" the rodent to the cat. Once the rat is eaten the parasit can complete its vital cycle!

Example 2. The fungi of the genus Cordyceps (perhaps thousands of species) that live in the tropical jungle needs to complete their cycle a quite precise environment - 94-95% of humidity, and 20-24 degrees Celsius of temperature. Each species colonizes an insect, and then it changes its behavior. Cordyceps unilateralis infects carpenter ants. It enters the body through the holes the insect utilizes to breath. The fungus "eats" the soft -non-vital tissue first, and start to release chemical substances in the ant's brain. This changes the ant behavior. She starts to climb bushes up to a level in which temperature and humidity are appropriate for the fungus. Then the mycelia of the fungus destroy the ant's brain and the fruiting body of the monster fungus starts to grow from the back of the dead ant's head. The ant's body is anchored to a steam or leave due to a ferocious bite of the ant's jaws somehow produced by the fungus. From there the fungus start to sparse its spores.

Example 3. The worm "Spinochordodes tellinii" or hairworm (aka gordian worm) requires to live in the water to complete its cycle of reproduction. The juvenile worm form parasites terrestrial arthropods. When it reaches the adult size, the arthropod changes its terrestrial habitat for the water where it perishes, leaving the worm in its vital final habitat where it can reproduce.

Example 4. The worm Leucochorium Paradoxum lives its adult life in the intestine of some birds. There they reproduce and lay eggs. This eggs fall to the earth where the snails eat them. Inside of the snail's intestine, the eggs evolve into different stages (miracidia, sporocyst, and cercaria). The last stage (cercaria) are contained in broodsacs that invade the snail's tentacles causing a pulsating, brilliant and colorful display. Somehow the behavior of the snail changes and it abandons the earth floor and climb to the high branches of the trees exposing the snail to its predator the birds! In this way the worm complete the cycle.

Example 5. Wasps of the genu Glyptapanteles lay eggs inside caterpillars. When the larvae is fully developed emerge through the body wall and attach themselves to a branch. The caterpillar remain aside with a total abnormal behavior: it will keept an arching body posture, and when some other insect approaches it moves violently with whip lash movements to protect the cocoons!

Example 6. The flat worm dentriticum lives its adult life in cow's liver. The eggs are excreted in the feces and after passing to snails end up in the guts of ants. The developed larvae now as "lancet flukes" invade the sub-esophageal ganglion, a nerve center of the ant. From there it takes control of the ant, changing its behavior, making the insect to climb the grass blades and clamps its mandibles onto the top of the blades where cows will eat easier to complete the cycle.


by Byron Bernal