The simplest animal in the world

1999/12/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Zoologia

The simplest animal in the world is not the sponge, but a small worm of the conditioning group. The worm is a parasite of octopus and squid with a high degree of specialization. The animal's body is the only long cell with about 10 to 40 additional cells, no digestive tract, no muscle, no nervous system.

Until now it was thought to be something between unicellular beings and more complex animals. Researchers have studied the genetic code of the worm dicemya orientadora (one of the worms that make up the group) and have found the same scheme as a very special gene that some mollusks and worms possess. The conditions, therefore, are not primitive beings of low development, but animals that have become to simplicity from more complex beings. How to explain it? One of the laws of evolution says that what is not used is lost. This often occurs in parasites: the more they come from the host, the less they need specialized functions and, with use, the functions will disappear. www.quebecscience.ca