The Environmental Science Graduate Students at Watlings Castle, San Salvador, Bahamas.(TME 98)
Bahamas Course 2003
Dr. Hays Cummins
Would you believe me if I told you that a sea creature such as the Octopus has the ability to problem solve, similar to humans, having a developed short and long-term memory? Well it’s true; they have the most developed brain of all invertebrates (Ingrao 1). Their intelligence, along with their ink sac and chromatophores, assist the octopus in escaping their predators such as the whale, seal, or other smaller fish. How about if I told you that the mother octopus dies after the hatching of her young? That’s also true, the mother does not eat during the 50 days from when the eggs are laid and are hatched, therefore dying of starvation upon her young hatching. An octopus’ ability to camouflage is superb, due to these chromatophores; the octopus can change its color in less than a half of second. This makes it the fastest coloring changing animal in the world! (Guerrini) These are only a couple of the fascinating abilities of the many species of octopus. The octopus has a very unique body make up, very interesting feeding and digestive behaviors, and its reproductive behavior is quite fascinating, making the octopus a wonderful creature to learn about.
Octopuses belong to the phylum mollusca, with their closest relatives being the squid and cuttlefish. There are about 100 species of octopus, with both the largest and smallest species being found off the coast of the United States. The largest, the North Pacific octopus, where many of the octopus fables come from, can reach up over 30 feet from the tip of one tentacle to another and grossing over 100 lbs (Ingrao 1). The fables I am referring to are the sea tales, more often told centuries ago, where giant octopus’ would attack ships at sea, killing and eating the men on board. These octopus’ were greatly exaggerated in size and tendency to attack man, for that is practically nonexistent; as the blue ringed octopus is one of few species with strong enough venom to even kill a human, it does not happen very often (Dozier). The blue ringed octopus’ venom is so toxic to its prey that the mere presence in the water of the octopus is strong enough to kill some of its crustaceous prey, a remarkable amount of potentancy.
The octopus cn get as small as 3/8th’s of an inch at full growth, such as in the Californian Octopus. Species such as the Californian and Pygmy, which gets no larger than four inches, are often found washed up on U.S shores inside of sea shells, where they have attempted to take refuge, which has ironically taken them to death (Ingrao).
The bodily make up of an octopus is fairly simple to the naked eye, although deceives the truly intricate body the octopus has. All of the organs rest inside the mantle, the large, round muscular cavity of the octopus. IT HAS THREE HEARTS The muscled mantle will expand and contract, allowing the octopus to use jet propulsion, mostly to escape from their enemies. Here the mantle will be in a relaxed state, filling up with water, and then when the animal feels it needs to escape, will contract the mantle forcing all the water out of its funnel, a narrow opening on the ventral side of the mantle allowing for a jet propelled getaway (Burton, Devaney, & Long).
An interesting feature(s) an octopus has is its three hearts. Two of these hearts rest at the base of the two gills where the octopus receives water from, and these hearts will get the unoxygenated blood from the capillary of the gills. While here, the blood when then get oxygen rich, using the other heart to pass the blood to the median ventricle, where it will then be pumped to the rest of the body (Ingrao).
Another defense strategy to avoid predators such as seals, whales, and other larger fish, it uses is camouflage. As I mentioned before it can change its color to blend in with its surroundings in less than a half of second. It does this by using the chromatophores in its skin. They consist of three bags in each cell, that will expand and contract to adjust individually to the back ground in which the octopus is trying to blend into. It does this by using the chromatophores in its skin. The initial trigger of the bodily color change is started in the eyes, where the octopus will see something that it feels brings danger, and will start a chain of reactions ending with a bodily color change. An octopus will also use its ability to change color to reflect different moods such as white for fear, red when it is angry, and brown being the neutral color which you would most often see an octopus as (Guerrini). As a last line of defense, the octopus will squirt a cloud of ink at their predator, some species can squirt the ink in the shape of an octopus, others rely on the power to dull the senses and act as a smoke screen, giving the octopus a couple extra seconds to get away (Devaney et al.).
Branching off from the mantle are 8 tentacles, which the octopus uses to catch prey and maneuver along the rocky bottom of the ocean. On the ventral side of each of the eight tentacles reside hundreds of suckers, which assist the octopus further in movement and seizure of preys. For example, the octopus uses these suckers to pry open the shell of a clam, allowing it to eat the meat inside (Guerrini). The octopus can also smell with the suckers, and will often stick a tentacle down into crevices to smell what possible prey may be hiding in there. If it likes the smell it will simply grab it with that tentacle. Another prime example the octopus will use the suckers for is to hold tight to a large rock on the bottom of a coastal ocean, so it will not be taken away with the strong current. The octopus enjoys spending most of its time here, on the rocky bottom in coastal waters lurking around on the rocks. This behavior contradicts that of other cephalopods in the same phylum, such as the squid, which will stay moving for most all of its entire life, exploring both the shallow coastal waters and deeper waters (Internet 2).
Most of the octopus’ day is spent out of sight, usually deep in their den, which is well guarded by old crab shells. It is found that the octopus will even “shut the door” to its den with a shell blocking any creature from entry. This is another way in which the octopus exhibits its advanced intelligence (Internet 2).
It is then during the night, or in murky water at any time; the octopus will come out to hunt for a meal. The octopus enjoys eating crustaceans, small fish, and one of its favorites is clam. Often times an octopus will lure an animal in by wiggling one of its arms, looking like a worm, then once the prey is close enough will grab it with all the other arms and give the animal its paralyzing bite. It brings the animal up to its mouth, where it has a beak, and bites the animal injecting it with a poison, killing its prey. It may kill a multiple number of prey on an outing, stuffing the dead prey into its mantle for storage. Once the octopus has retrieved its desired amount of food it will return back to its den and release a digestive enzyme (Internet 2). After a couple hours the digestion process is over, and the octopus will then expel the hollow exoskeleton of whatever animal it has just caught (Guerrini). The digestive enzyme breaks down the flesh and insides of whatever prey the octopus has chosen so it may suck it up as a liquid. This makes it easier for the octopus to eat larger crustaceans and larger fish.
The octopus has a very interesting reproduction cycle, which ends with the mother dying at the time of her young’s birth. An octopus does not live more than five years usually, and no less than six months, but the female will always perish once her eggs have hatched (King). The cycle starts off with the male using his one, spoon shaped tentacle to reach inside his own mantle and remove a packet of sperm. He will then insert this arm into the hallow of the female where the sperm with come into contact with the ovaries. Here the eggs will be fertilized and will be ready for the female to lay them. The eggs will be laid in strings surrounded by a thick jelly coat, usually attached to weeds and rocks on the ocean bottom. Now an octopus can lay anywhere from 150 eggs from the Pygmy Octopus to 250,000 in the Common Octopus. Octopus which lay fewer eggs usually indicate that the eggs are larger and when they hatch will be almost full-grown. Opposed to those octopus which lay over 100,000, when they hatch they will float around as plankton for a few weeks before being able to swim on their own. Out of these 100,000+ Octopus eggs, only one or two will live to be old enough to give birth to their own young one day (Ingrao). But before they start swimming around it will take about 50 days, depending on the Octopus, for the eggs to hatch. During these 50 days, the mother will stay on guard at all times, constantly shooting jets of water on the eggs and brushing them with her suckers to keep bacteria and other growths off them, and a supply of fresh oxygen to them (Devaney et al.). The mother does not eat during this time period, which is the main reason to her death by the time the eggs hatch.
The ocean houses many wonderful creatures with amazing adaptations fit for survival. The octopus is one of many with such magnificent abilities such as the chromatophores, allowing it to blend in with its background in less than half of a second! Also with its highly developed brain, it has an edge over its prey and even some predators after it, whether it be luring them in with a tentacle posing as a worm, or shooting a cloud of ink into the face of a seal for a getaway, the octopus is always alert. Hopefully we will be lucky enough to see one of these creatures during our trip in the Bahamas. That would really be something to see an octopus changing color or using its jet propulsion or even squirting a cloud of ink (from a distance). I hope my paper has lead to a better understanding and knowledge to the octopus.
-Body make up
-Diet and feeding
SOURCES: 1- “The Great Book of the Sea” Francesco GUERRINI. Courage Books. Running Press Book Publishers, Philly, Penn. Copyright 1988
2- Wonders of the Sea. Robert Burton, Carole DEVANEY, Tony LONG, Exetar Books. New York. copyright 1976
3- THE WORLD BOOK ENCYCLOPEDIA printed in US,volume 14, a Scott Fetzer company
4- "The Animal World" The World Book Encyclopedia of Science
5- "Life in the Coral Reef" Thomas Dozier, Don Earnest from TV show: Wild,Wild world of animals; copyright 1958. Houghton Mifflin co.
www.tonmo.com/articles/basicoctopus.php, Nancy King
www.marinelab.sarasota.fl.us/OCTOPI.HTM , Debi Ingrao
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