Bio 101 Week 4 Assignment

Organism Physiology: The Octopus Bio/101 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.

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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 the octopus moves along the ocean floor, these neurons allow the octopus to learn its surroundings. They can remember the environments and keep a working memory of areas they have fed on in the past that may be more dangerous than others. When feeding in a treacherous environment both prey and predator must develop a varied range of hunting and defense behaviors.

Marine biologists that have studied cephalopods claim that their subjects even have personalities and “that octopuses engage in play, the deliberate, repeated, outwardly useless activity through which smarter animals explore their world and refine their skills” (Scigliano, 2003). One scientist claims that her octopus even “bubble surfs” by spreading his mantle out and letting the aerator jets from his tank run under his body (Scigliano, 2003). . Key traits were noted out of 73 lab-bred octopuses. Discoveries showed temperamental variations at different maturity levels.

Young octopuses tended to be active and aggressive whereas more mature ones tended to be more alert and quick to react to danger (Scigliano, 2003). Evidence that even though their lifespan is short their brain evolves and adapts quickly. Around the mouth of the octopus are eight arms. The eight arms allow the octopus to move, crawl, and swim around in its habitat. Octopuses crawl slowly, walking on its arms to move through the water headfirst with the arms trailing behind. When necessary, octopuses can move fast using their arms to propel it through the water similar to jet propulsion.

The suckers found on the underside of the arms aid in catching prey for food, and as a weapon when threatened by the enemy. Octopus facts for kid’s states, “Octopuses are stealthy hunters changing their color to match the surroundings as they hide. The octopus waits for the prey to arrive within reach, then grabs it and secretes a nerve poison, stunning the prey. ” In times of distress, the octopus can detach a limb and the crawling arm serves as a distraction to the predator, allowing the octopus to escape. The octopus will sometimes eat its own arm and the arm will re-grow later with no permanent damage.

A neurological disorder causes this (Octopus, 2008). The octopus will also detach a limb during reproduction. The male uses a special arm, usually the third right arm, called a hectocotylus, to insert sperm into the female’s cavity. The third right arm detaches during sexual intercourse and the male dies within a few months after mating. The excellent sense of touch in the octopus is due to the chemoreceptors in the suckers of the arms. These chemoreceptors help the octopus taste what it is touching, and sense when the arms are out but cannot determine the position of its body or arms.

The arms of the octopus are physically suited to the environment it inhabits to allow movement, reproduction, feeding, and defense. The octopus is known to be an intelligent creature and over time they have developed defense mechanisms to avoid its predators. The primary defense of the cephalopod is to hide or swim away. But when the octopus is scared it has the ability to release ink in a squirting fashion. The ink sac in an octopus can be found below it’s digestive gland. Located there is a small gland that produces the ink and then a larger muscular sac that stores the ink. The sac has a gland that connects to the anus.

When the octopus is scared, the ink is released from the ink sac through the anus and into the funnel where it is mixed with mucous. Melanin, the main component of the ink, clings to the mucous molecules giving morphing into a cloud-like illusion allowing the octopus to swim away and leaving the predator confused. In addition to having melanin, the ink also contains tyrosinase, a very irritating chemical that temporarily suspends the predators sense of smell and irritates the eye (Mather, Anderson, & Wood, 2010). While not all species of octopuses have an ink sac the majority still alive today do.

The exceptions to this are cephalopods that live in deeper, darker waters where there is very little light. The defense is useless unless the attacker has light to see (Mather, Anderson, & Wood, 2010). The octopus is a unique organism that is able to adapt to any environment it inhabits. The brain enables the octopus to solve problems and the ability to remember its surroundings, the brain works with the octopus’s arms similar to the way the brain works the human limbs. The brain sends neuron signals to the arms and the arms carryout the tasks that are signaled by the brain.

The octopus can detect a predator and send out a decoy known as an ink screen that disorients and confuses the predator. This allows the octopus to escape and find a hiding place. The physiological development of the organs in the octopus ensures its survival in its habitat, and makes it an excellent hunter. References Buzzle. com. (n. d. ). Octopus facts for kids. Retrieved from http://www. buzzle. com/articles/octopus-facts-for-kids. html. Deb, S. (2010). Octopus brain. Open. Retrieved from http://www. openthemagazine. com/article/voices/octopus-brain. Horton, J. (2008). How octopuses work. Discovery.

Retrieved from http://animals. howstuffworks. com/marine-life/octopus3. htm#. Mather, J. , Anderson, R. , & Wood, J. (2010). Octopus: the ocean’s intelligent vertebrate. Portland, Oregon: Timber Press. Miller, G. (2009). Tackling brain evolution with all eight arms. AAAS. Retrieved from http://blogs. sciencemag. org/origins/2009/10/tackling-brain- evolution-with. html. Octopus. (2008). New World Encyclopedia. Retrieved from http://www. newworldencyclopedia. org/entry/Octopus? oldid=794938. Scigliano, E. (2003). Through the eye of an octopus. DISCOVER. Retrieved from http://discovermagazine. com/2003/oct/feateye.

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