Eight Arms are Better Than Two

By Anonymous -
Eight Arms are Better than Two

Hannah Yarbrough, Ben Book, Sidney Ketchum

Octopus, a creature so unique, swims our oceans with three hearts and eight tentacles. While they typically roam these waters alone, the plural form of octopus is octopuses, not octopi as many believe.  There are close to 300 species of octopuses. Octopuses are a part of the Cephalopoda class, which also includes cuttlefish, squids and nautilus.  These intelligent creatures live fascinating lives.  Let’s dive in and take a look at the places they call home, the ways they “get it on” and how they fight off those cruel enemies.

HABITAT

https://www.nationalgeographic.com/animals/
invertebrates/c/common-octopus/
Octopuses can be found in various locations within the oceans.  However, they are more commonly found near coral reefs.  Reefs provide nooks and crannies for them to make their homes.  Much like a couch-surfer, these animals do not stay in one location for too long.  They like to move every couple weeks and live in a variety of places.  If you dare, attempt to locate the octopus in his home to the picture on the right.  

Octopuses have the ability to live in a wide range of temperatures.  A good majority can be found living in the depths of the ocean.  The rest can be found living happily in shallower waters closer to the surface.  One place the octopuses find extremely difficult to thrive in are places filled with pollution.  Due to the toxins, they find it difficult to find meals as well as lay eggs.  On the plus side, octopuses are smart cookies that can make many unique locations their home.

REPRODUCTION

Watch this short animation on the reproduction strategies of octopuses.

When it comes to reproduction, male and female octopuses have an interesting way of reproducing. First off, the female octopus is much larger than the male octopus, making the male terrified of the female. But if that wasn’t scary enough, the female octopus is a cannibal, constantly hungry, and will strangle and consume the male octopus if he does not move carefully. The male octopus has many tricks though. He can literally mate at arm’s length, completely disguise himself as a female and sneak into her den, or detach and sacrifice his arm while he makes a hasty getaway. Octopuses are some of the most unsocial creatures in the ocean, yet they mate in the most intimate way as the male inserts his arm into the female’s mantle so that his sperm can go directly into her body for the female to store until she is ready to lay her eggs.

https://www.pinterest.com/pin/333055334921275812/
For the particular species, Enteroctopus dofleini, reproduction is their main goal in life and once they accomplish it, they will die. The octopuses locate each other by the female producing chemicals that the male can sense as he searches for her. As they begin the courtship, they will use their sight to determine if the other is a compatible match or not. The female is always larger than the male, so that’s what the male is looking for in a mate because a larger female produces more eggs. The female is looking for a male with a long ligula, which is a section on the hectocotylus located at the end of one of the male’s arms. To attract his mate, the male will flash displays on his skin using his chromatophores. The whole courting and mating process can take up to three or more hours. The male octopuses spermatophores contain up to seven billion sperm and can be three feet long and he places them into the female’s body from his hectocotylus into an opening in her mantle. The female will store the sperm until she is ready to lay her eggs, which will be anywhere from 20,000 to 100,000 eggs. It will take her a couple of days to lay all of them. After that, she will spend the rest of days caring for them until they hatch.

The final stage of the octopuses life cycle is senescence, where both the male and female experience a dementia-like state that causes them to lose a lot of weight because they refuse to eat. They will lose 50 percent of their body weight because they metabolize muscle since their body is not able to store fat. The males tend to just float around, making them extremely vulnerable and easy prey, while the female will die shortly after her eggs hatch. White lesions that don’t heal will appear on the skin of both male and female octopuses, showing the last signs of senescence. They experience this unfortunate situation until their death.

DEFENSE MECHANISMS

Octopuses are an ideal delicacy for many predators in vast, diverse ocean. Being somewhat small, and extremely soft, they are specifically targeted because they have no exoskeleton, thus making them relatively easy to digest. The octopus must protect itself from eels, sharks, dolphins, etc. Based on the physiology of the cephalopod, the alternative to fight a predator is nonexistent and could possibly result in death. Instead, the octopus relies on defensive tactics: camouflage, ink sacs, detachable limbs, and mimicry which we see in the “Mimic Octopus.”

Thaumoctopus mimicus, a species that lives off the coast of Indonesia, specializes in mimicry. It can take on the appearance of a flounder, a sea snake, and even a bottom dwelling flatfish. By contorting its body and keeping its own color of brown and white stripes, the octopus can hide in plain sight. Even though it isn’t totally camouflaged, the fact it can lengthen and contort its body to resemble a fish is uncanny. It is unknown if these skills are learned or inherited, but I am sure the truth will present itself in due time.  These defense mechanisms allow this cephalopod to survive a little longer in a very short, lonely life. 

Click here to watch the mimic octopus at work!


If you wish to learn more about octopuses in a fun way, please watch Pixar's Finding Dory!

http://www.thepicturehouse.org/finding-dory/





SOURCES

  
Baker, Beth. “Unusual Adaptations: Evolution of the Mimic Octopus.” BioScience, vol. 60, no. 11, 2010, pp. 962–962. JSTOR

Courage, Katherine Harmon. “Earth - How male octopuses avoid being eaten by hungry females.” BBC, BBC, 24 Feb. 2015, www.bbc.com/earth/story/20150223-mysteries-of-cannibal-octopus-sex.

Kalupa, Julie. University of Wisconsin. 2012. http://bioweb.uwlax.edu/bio203/s2012/kalupa_juli/reproduction.htm

OctopusWorlds. 2014. http://www.octopusworlds.com/octopus-habitat/

OneKind Planet. OneKind Planet. 2017. https://onekindplanet.org/animal/octopus/

Vendetti, Jann. University of California Museum of Paleontology. 2006. http://www. ucmp.berkeley.edu/taxa/inverts/mollusca/cephalopoda.php


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