Crafty Creatures

Octopuses are known for being sneaky both in the wild and in captivity. They have a knack for creeping up on their prey and disappearing in the blink of an eye, but what enables them to do so? Their main defense tactics are hiding, camouflage, and inking. Their soft flexible bodies and clever thinking allow them to hide in small spaces, and their powerful bodies make them fast swimmers, which is a useful skill when they need to make speedy getaways. An octopus can quickly force water out of its siphon to create a jet propulsion effect, and can travel several miles on this momentum. If they aren't able to avoid a predator's grasp, some octopuses can purposefully detach their own arms in a process known as autotomy. Their limbs regenerate over time, like lizards who undergo autotomy can regrow their tails. The Mimic Octopus (Thaumoctopus mimicus) is unique because it can practice mimicry. They can imitate the appearance and movement of other marine animals such as lion fish, sea snakes, and brittle stars in order to fool both their predators and their prey. If you're interested, this video shows some of their amazing disguises. It's the craziest thing!

Octopuses have a special organ called the ink sac, which produces a dark ink made of melanin. When they feel threatened, an octopus will squirt a cloud of ink as it quickly swims away. The ink can obscure a predator's vision and interfere with their sense of smell, as well as act as a decoy that can confuse an attacker while the octopus escapes.

One thing octopuses are most recognized for is their ability to change the color and texture of their skin. Octopuses do this in order to communicate with other octopuses and blend into their surrounding area. Octopuses contain chromatophores in their epidermis which can emit pigmentary wavelengths of yellow, orange, red, brown, and black. In order to change the texture of their body, they use the many muscles located under their skin. However, it has been speculated upon that octopuses don’t contain all five of these colors. Scientists think that most octopuses have about three of these colors but some can have only two or even four. In our experiments while working with the Two-Spotted Octopus, we found that it was only able to change to about 3 main colors, Red, Yellow, and Brown. We are guessing that this is an octopus that falls under the category of only being able to change to three of the five colors. These specialized skin cells are also said to be able to change the color, opacity, and reflectiveness of the octopuses epidermis. They also utilize this ability to disguise themselves when hunting for food, and strike unsuspecting prey with their long arms and powerful tentacles when they least expect it.

As soon as it catches its food and brings it to its mouth or beak, they give it a deadly, poisonous bite, guaranteeing that their prey is a goner. They then secrete a nerve poison from their beak (cephalotoxin or neuromuscular venom) that stuns their victim. In some cases, their venom can be toxic or even deadly to humans. An example would be the Blue-Ringed Octopus (Hapalochlaena maculosa). These guys can kill a human with their secretion of neuromuscular venom.

(Source: http://marinebio.org/species.asp?id=403)

The octopus would not be the wily wonder that it is without its excellent eyesight, complex senses, and remarkable intelligence These are some of the most fascinating things about octopuses, making them so mysterious and different from any other organism we know, while at the same time somewhat similar to ourselves. Something neat is that octopuses have the ability to taste what they are touching due to the chemoreceptors located in their suckers. Also, something random we didn’t know is that octopuses are actually deaf or have very limited hearing.This, as well as their cleverness in solving puzzles, interaction with people, escape from enclosures, and so much more are just examples of their well-developed brain. Certain maze and problem solving experiments have proven that octopus have both short and long term memory, as well as observational learning by recognizing shapes and patterns. However, octopuses are not able to connect their actions between their arms and brain. For instance, the brain will issue a command to the arms like “Grab this clam” but it is actually the nerve cords in the arms that execute the action not the brain that makes it happen. In a sense it is almost as if the arms have a mind of their own. The brain is not able to receive feedback about how the command was executed but the octopus must instead look with its own eyes to see if their arms followed through with that action. This is definitely a strange concept for us to comprehend; imagine not knowing where your own arm ends!

(Source: http://www.daviddarling.info/images/octopus_eye.jpg)

Octopuses are known to have highly developed eyes but scientists don’t know a whole lot about them at this point in time. We know that the octopus is able to distinguish between different shapes and patterns and we guess that they have some kind of color vision due to the fact that they are able to change color and camouflage their bodies to their surroundings. We do know that they are able to see polarized light. The eye of an octopus is surprisingly very similar to the construction and complexity of the human eye. However the eye of an octopus has photoreceptors in the retina that are directed toward a source of light, this being classified as a “direct” eye. They seem to have almost more efficient eyes than us humans in theory, due to their ability to have a wider field of clear vision, better resolution, and sensitivity to light. Comparing the octopus eye to a camera lens helps put it function into perspective. In a camera, the lens has a fixed focal length. Well, an octopus eye is like a camera, its eye lens also having a fixed focal length. However, the octopus is able to manipulate its entire eyeball to focus instead of just the lens alone. A typical vertebrate only has the capability to focus its lens.


Research from:
Cephalopod Behaviour, by Roger T. Hanlon & Roger B. Messenger
Tales from the Cryptic: The Common Atlantic Octopus, by Nadia Meyers (http://www.dnr.sc.gov/marine/sertc/Featured%20Species%20O%20vulgaris.pdf)
http://news.nationalgeographic.com/news/2001/09/0920_octopusmimic.html
http://www.octopus.com/anatomy/http://animals.nationalgeographic.com/animals/invertebrates/common-octopus.html
http://www.bio.unc.edu/faculty/kier/lab/research.html
http://marinebio.org/species.asp?id=403
http://www.factsmonk.com/octopus_facts
http://www.wikipedia.org/

Octopus 101

So as many of you may know, octopuses belong to the phylum Mollusca. Members of this phylum are bilaterally symmetrical soft-bodied invertebrates with some form of hard shell. They each have a nervous system, an open circulatory system, and a complete digestive tract. In case you were wondering where octopuses fit in the grand scheme of life, here's the scientific classification:

• Domain: Eukarya
• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Order: Octopoda
• Genus: Octopus

Their closest relatives are cuttlefishes, squids, and chambered nautiluses, which are all of the class Cephalopoda. So far, about 700 species of cephalopods have been discovered (Hanlon & Messenger). Unlike their fellow cephalopods which all have some sort of shell structure either externally (like the shell of a nautilus) or internally (cuttlefish have a cuttlebone that helps with buoyancy, and squid have a long thin pen that supports their bodies), the only hard part of an octopus's body is their beak. This enables them to squeeze into unusually small spaces, as long as the opening is larger than their beak.

(Source: http://www.octopus.com/anatomy/)

To refresh your memory, an octopus has a head, a mantle, and eight arms. The beak, eyes, and complex brain are all located in the head. The mantle holds the octopus's internal organs, such as its digestive tract, kidneys, and three hearts. One heart pumps blood, which is actually blue, throughout the octopus's body. The other two hearts, known as the branchial hearts, pump blood to the gills where they absorb oxygen as water flows into the mantle. This water is then forced out of a tube called the siphon.

Each arm has one or two rows of suckers along its entire length. These suckers are connected to nerves, which enables the octopus to use them to grab and taste food and other objects. A Giant Pacific Octopus (Enteroctopus dofleini), which is the largest octopus in the world, has two rows on each arm and can have about 1,600 suckers total (FactsMonk). That’s a lot of suckers! Octopus arms are muscular hydrostats, which makes them very strong and flexible. This helps them catch and kill large prey, and even perform some of those escape artist tricks they are known for, such as lifting a heavy lid off of their tank. Muscular hydrostats are basically a mass of muscle that act as skeletal support would in another animal. However, instead of a rigid structure that restricts certain kinds of movement, the muscular hydrostats can bend, elongate, shorten, and twist at any part, even at several parts all simultaneously. This is the same structure that makes up a worm's body, an elephant's trunk, and our tongues!

(Source: http://www.wired.com/wiredscience/2009/09/octopuscontrol/)

Speaking of tongues, octopuses have a radula, also known as a rasping tongue, inside their beaks. The radula has tiny little teeth that scrape food into smaller pieces before swallowing. Octopuses eat mainly crabs, crayfish, and mollusks, including other octopuses. Their predators are seals, sharks, dolphins, eels, and humans. Octopuses are a delicacy in many cultures, especially in Japan, Portugal, the Mediterranean, and Hawaii, and are sometimes eaten alive. According to the USDA, octopuses are actually a good source of B3, B12, potassium, phosphorus, and selenium, but we prefer to think of them as friends rather than food!

(Source: http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/IMAGES/squid_radula.gif)

Sadly, octopuses typically don’t live very long lives; on average their life span is only about one to two years. The Giant Pacific Octopus is the longest-lived; males live to approximately 4 years and females to about 3.5. Males die after mating, and females die shortly after their eggs have hatched. Information for how many eggs an octopus lays is extremely varied but from what we have gathered it seems that they can produce a couple thousand to about two hundred thousand. It seems to depend on the species and individual. The female usually hangs her eggs in strings coming down from the ceiling of her little haven or she individually attaches each egg to the substrate, once again, this depends on the species. The female has a tough life caring for her soon to be born babies. She spends her time guarding them from predators and blowing small currents of water over the eggs so that they are able to get enough oxygen. The female octopus also does not hunt at all during the approximate one month period that she takes care of her eggs and may even ingest her own arms for sustenance! When her eggs finally hatch, mom leaves her little haven but she is extremely weak due to not eating, therefore causing her great vulnerability. She dies soon after her eggs hatch anyways but she is more likely to be eaten by a predator since it is unlikely she will be able to defend herself. Octopuses are not social animals in that they don’t have contact with their mother or learn skills from her. Octopus learn on their own and don’t have any influence from parents or siblings. After her little babies hatch out of their eggs, the young larvae spend their beginning stages of life drifting in clouds of plankton at the surface of the ocean. While drifting they are able to feed on copepods, and larval crabs and starfish. They eventually descend back to the bottom, returning to the deep, but only if the babies are lucky enough to survive the treacherous plankton cloud. In this cloud they are very vulnerable to other plankton eaters. As adults, octopuses live on the ocean floor. One thing we thought was pretty neat is how octopuses will sometimes collect random objects like coconuts or crustacean shells that they come across along the seafloor, and make little homes out of them.

Red Octopus

(Source: http://sanctuaries.noaa.gov/pgallery/pgolympic/living/octopus_300.jpg)

You can find octopuses in all the oceans of the world. The Giant Pacific Octopus, which we have here in our aquarium, is found along coastal waters of the North Pacific. Another species found in Monterey Bay is the Red Octopus (Octopus rubescens). Hopkins Marine Station has an adult Red Octopus, which was caught by one of the lab's scientists when he was diving. However, due to its wild and quirky behavior this little guy can be pretty tough to work with, so we're lucky that the lab also has baby Two-Spot Octopuses (Octopus bimaculoides). The babies, which were collected in Santa Barbara and hatched at Hopkins, are much easier to handle, and are also extremely cute!

Two-Spot Octopus

(Source: http://static.howstuffworks.com/gif/octopus-6.jpg)

Research from:
Cephalopod Behaviour, by Roger T. Hanlon & Roger B. Messenger
http://www.octopus.com/anatomy/

http://animals.nationalgeographic.com/animals/invertebrates/common-octopus.html
http://www.bio.unc.edu/faculty/kier/lab/research.html
http://marinebio.org/species.asp?id=403
http://www.factsmonk.com/octopus_facts
http://www.wikipedia.org/

The First Hurrah!

Hello!

We are writing this blog to share our research and findings about octopus intelligence and eye function. Many of you may have heard stories of cephalopods recognizing their caretakers or solving various puzzles, and we are eager to learn more about these fascinating creatures. We want to understand how octopuses learn and perceive their worlds, and how they use their intelligence to overcome obstacles. What makes these mysterious creatures so advanced and easy to relate to, when they are so different from ourselves?

To start our project, we took a trip to Hopkins Marine Station in Pacific Grove, CA on March 23, 2010. We were lucky enough to have been introduced to Judit Pungor, a cephalopod researcher and enthusiast. She showed us around the station and the octopus lab she works in, told us about her current work, and familiarized us with the lab's interesting creatures. We discussed the intent of our project, and Judit helped us narrow our focus so we could research more efficiently. Before we left, Judit offered to take the adult Red Octopus (Octopus rubescens) out to introduce it to us, but the moment she took the heavy weight off its tank, the sneaky little guy tried to push the lid off the tank and leap out, splashing water all over the place in the process.

We learned a lot during just our first visit, such as the possibility that octopuses may be able to see polarized light. This inspired us to consider various experiments we could perform to test the presence and usefulness of such an ability. We plan to go visit Hopkins soon so we can conduct our own experiments, and get to know the octopuses a little better!

Until next time!
-Emma and Malwina