Bio 101 Week 4 Assignment

Brain, Cephalopod, Octopus

Organism Physiology: The Octopus

The cephalopodor octopus is a marine organism that inhabits many diverse regions of the ocean. Its food source consists of crabs, small fish, clams, mussels and other marine animals. The octopus is a predatory animal and has developed many skills to aid in its survival in the environment it has adapted to.

The octopus has several main organs that are vital to its survival; the brain for its intelligence; the ink sack for its defense; and the arms for capturing its prey. This paper will discuss these different organs and how they have evolved physiologically to its environment.

Unlike its other cousins in the Mollusca family, octopuses have a considerably large brain in comparison to their bodies. In fact, they have the largest and most complex brain of any invertebrate. Even in the United Kingdom, under the Animals (Scientific Procedures) Act of 1986 has given the species a title of honorary vertebrate (Deb, 2010).

The brain sits just below the optic canal and wraps around the esophagus of the octopus. The brain is composed of 50 to 75 lobes and about half a billion neurons. Roughly two thirds of the neurons lie in the arms of the octopus, which uniquely have their own nervous systems (Miller, 2009). It is hypothesized that the brain of the octopus gives a task to the arm and the arm essentially decides how to carry out that task. An experiment was done that involved separating and cutting the nerves of the arm from other nerves in the body and then tickling the arm. The response showed the injured arm reacted just as a healthy octopus’s arm would (Horton, 2008). All of this unique circuitry gives the octopus immaculate control over their bodies.

The octopus prefers movement in a style closest to walking. Suckers on each arm move in unison to propel the octopus. Each sucker has up to 10,000

neurons in it (Horton, 2008). As...
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