Octopus Ink: What Does it Do?

A few years back, we explored the the mechanics of how octopus inking works. To recap, octopuses have an ink sac located near their digestive system, and when necessary, they can eject ink out of the sac accompanied by a burst of water to serve as a smokescreen to confuse predators while the octopus swims away.

Octopuses have two main methods of inking. The first type is the one with which we are most familiar. The octopus will squirt a large cloud of ink, then make a quick getaway, leaving behind a predator befuddled by the inky smokescreen. Sometimes though, the octopus will release several small clouds of ink approximately the same size as the octopus itself meant to be pseudomorphs or "false bodies" that serve as decoys to confuse the predator. What's interesting is that the composition of these smaller ink "bodies" differs from that of one large ink cloud as they contain greater amounts of mucus, thereby allowing them to hold their form longer while the octopus - or cephalopod - escapes.

This method, commonly referred to as "blanch-ink-jet maneuver", is so effective a variety of species have been witnessed attacking the false bodies.

Wait - it gets better! There is some evidence to suggest that certain chemical compounds found in octopus ink actually suppress or disable certain predators' chemosensory systems, leading scientists to believe that octopus ink is much more than a mere smokescreen.

Cephalopod ink has been shown to contain several chemicals with some varieties depending on the species. The primary components are melanin and mucus. Tyrosinase, dopamine and L-DOPA, and small amounts of amino acids, including taurine, aspartic acid, glutamic acid, alanine and lysine are also known constituents of octopus ink.

While there is still much research to be done, recent evidence suggests that cephalopod ink is toxic to tumor cells.

We have a long way to go to uncover the many mysteries shrouding the octopus, so please join us as we continue to explore and celebrate everything octopus.

Explore the Complexity of Octopus Brains

Pop some corn, get cozy, and watch this amazing and informative video from BoingBoingVideo.



Octopus Video Description

Everybody loves cephalopods—that class of animals containing octopuses, squid, and cuttlefish. But why? What makes these non-fluffy, non-mammals so appealing?

Last August, I attempted to answer that question in a presentation for a University of New Mexico IGERT symposium (http://www.chtm.unm.edu/incbnigert/2010Symposium.html). "Those Fabulous Octopus Brains" is a speech linking cephalopod neurobiology to cephalopod behavior, and asking what it really means to call a species "intelligent". It'll get you caught up on what we do, and don't, know about cephalopod smarts—and what studying these amazing creatures means for the future of human technology, and our understanding of the human brain.

Don't have time to watch the entire thing? Never fear. The intrepid editors at BoingBoing Video have put together a highlights reel that will enlighten you in a 1/3 of the time.

Polarized Display Sheds Light on Octopus and Cuttlefish Vision – and Camouflage

Written by Katherine Harmon
Originally posted on blogs.scientificamerican.com on February 20, 2012

Octopuses are purportedly colorblind, but they can discern one thing that we can’t: polarized light. This extra visual realm might give them a leg (er, arm) up on some of the competition.

And a team of researchers has created a new way to test just how sensitive cephalopods are to this type of light. Their results were published online Monday in Current Biology.

“We now know that polarization is tuned much more finely than we thought it was,” says Shelby Temple, of the Ecology of Vision Laboratory at the University of Bristol in the U.K., who led the study.

Image courtesy of Shelby Temple
But testing polarized light is tricky, especially since we humans aren’t tuned to see it. As Temple and his co-authors wrote in their paper: “For animals that can see it, the polarization of light adds another dimension to vision, analogous to adding color to a black and white image.” Polarized light is different from what we see in that it comes from a single angle, and animals that can detect it seem to see it in different resolutions based on changes in its angle. (The closest we can get to using it is putting on a pair of polarized lenses to cut down on glare.)

Polarized light perception in the best-tuned animals was assumed to be limited to differences of about 10 to 20 degrees. But in the group’s new experiments, the mourning cuttlefish (Sepia plangon) responded to just 1.05-degrees change of polarized light orientation.

For the experiments, the team used computer screens that had had the polarizing light filter removed (without these front filters on our liquid crystal displays—LCDs—our monitors would project polarized light images that we wouldn’t be able to see).

These modified displays played digital movie versions of “looming stimuli” such as an expanding circle, which would suggest a potential predator approaching. But instead of a color or intensity-based image, the one they created was based on changing polarized light orientation only.

Image courtesy of Shelby Temple
Octopus don’t yet seem to be quite as sensitive as cuttlefish to the fine gradients in polarized light, responding only after about 10 degrees shift. But, says Temple, “it may be the way that we’re testing.” As he points out, cuttlefish’s knee-jerk response to an approaching predator is a quick change of color, which the researchers could use as an indication that they had seen even fine shifts in the polarized light angle.

“Cuttlefish, they wear their emotions on their sleeve, quite literally,” Temple says. “They’re showing everything that they’re doing as a neural response.” In fact, the cuttlefish responded so well, that he and his colleagues thought they were doing something wrong. They were afraid that in the digital renderings they might have accidentally included a non-polarized light clue, such as brightness or intensity. But they went back and checked and found that it was, indeed, just the slight change in polarized light that was frightening the animals.

With octopus, “there’s no comparison,” he says. But, he concedes that it is possible that the octopuses might have seen finer resolutions of polarized light shift but just didn’t have the same simple, speedy reaction as the cuttlefish.

And says Temple, “it could be that some species could do it better than others.” So far, he has found that the blue ringed octopus looks to me more sensitive than the day octopus. He has plans to test different species of octopus soon.

Researchers are still working to get to the bottom of cephalopod vision, which is turning out to be highly complex. And this new work supports the idea that such sensitivity to polarized light emerged precisely because these animals don’t see color well—if at all.

Image courtesy of Shelby Temple
And if octopuses, cuttlefish and squid—and some of their predators and prey—can see polarized light so keenly, are they also using it, as they use color and luminosity, to actively create camouflage?

Other researchers are working on that very question. And Temple and his colleagues have observed that, at least in some cuttlefish, they can create a polarized light-based pattern on their skin. This play in light might “be used as part of a covert communication channel, invisible to animals lacking polarized vision,” they wrote.

But the patterns remain tricky for us to pick up on. For that, Temple and his colleagues have developed a way for us to get a peak into the invisible world of polarized light and dark by modifying a digital single-reflex lens (SLR) camera and creating a computer program to feed false-color into varying degrees of polarized light. These mysterious rainbow-colored ecosystem images make it clear that, “We’re not done with the story yet, for sure,” Temple says.

Octopuses Capable of Hand-Eye Coordination

By Helen Albert, CosmosMagazine.com
May 30, 2011

LONDON: Octopuses are able to use visual cues to guide a single arm to a location, a complex movement that was not thought possible due to their lack of a rigid body structure, say researchers.

The octopus' arm is made up primarily of muscle with no skeletal support, so octopuses were previously believed to have a low level of body awareness and only limited control over their limbs. However, this study has shown for the first time that they can direct a single arm in a complex movement to a target location.

"Octopuses have a central nervous system that is advanced for an invertebrate, but simple compared to a vertebrate, yet it is capable of controlling a much more 'difficult' arm," said lead study author Tamar Gutnick, a researcher at the Hebrew University of Jerusalem in Israel.

"Because of the unique body plan of the octopus its ability to control a single arm in a complex movement is quite amazing."

Too soft for complex movement?

Octopuses were thought to have no conscious central nervous system-directed (CNS) control over their arms with movement being controlled solely by the activity in the complex array of nerves (PNS) present in the limbs.

However, the visual aspect of the task carried out by the octopuses in this study suggests that there must be an exchange of information between the CNS and the PNS during such behaviours.

Photo by Tamar Gutnick
In Gutnick and colleagues' experiment, six out of seven octopuses succeeded in using a single arm to select a visually marked compartment containing a food reward in a three-choice, plexiglass maze.

The animals were required to reach the compartment containing the food reward at least five times in a row out of a total number of trials ranging from 61 to 211. The octopuses could only use one arm to complete the task, as the tube leading to each compartment was only wide enough for one limb.

How brains control behaviour

The team observed that the chance of a successful trial improved significantly during the last 20 trials for each animal compared with the preceding trials.

They also noted that the animals seemed to learn that they needed to see the three boxes to improve their chances of getting the reward and were significantly more likely to be in view of the boxes during the last 20 trials than during the earlier tests.

The octopuses also adapted their arm use strategy from mostly 'straight', involving a direct unrolling or pushing upwards of the arm through the tube, to a 'search' strategy, involving probing and crawling in the central tube and above the choice boxes before deciding on a compartment.

Photo by Michael Kuba
It's not automatic

"This is a very important step in our knowledge of octopus behaviour," commented Jennifer Mather, a professor of psychology and expert on octopus behaviour at Lethbridge University in Alberta, Canada.

"The octopus has a large number of complex arms, and the question of how they manage to guide all of them is a fascinating one. We had previously thought that it might be fairly automatic or that their control was more at the local level within the arm. This is good evidence that local control need not be all," she added.

Studies involving octopus motor control, such as this, are the foundation of a current European Union research project to develop a robot octopus (Octopus Project). The aim of the project is to design and produce a soft-bodied robot that moves and squeezes through narrow spaces in a similar way to a biological octopus.

"Depending on the size of the robot its use could be from medicine (constructing new soft-bodied ultra flexible surgical tools) to big robots that could be used in search and rescue," said Gutnick, who is continuing her research on motor control.

"We are continuing to look at single arm tasks where animals are taught using a variety of senses, exploring the involvement of central and peripheral information," she said.

Ancient Octopus Mystery Resolved

By Rosalind Pidcock
Science reporter, BBC News

May 19, 2010


Trapped air in the shells of rare octopuses is the key to their survival in the deep sea, say scientists.

Females of the argonaut family (Argonautidae) release trapped air from their shells to control very precisely their movement through the water.

This ability has puzzled naturalists for over 2,000 years, dating back to observations made by Aristotle in 300 BC.

Research published in the Royal Society journal, Proceedings B, finally explains why it may have evolved.

The Australian researchers describe how the mechanism enables the creatures to conserve energy, avoid predators and protect eggs during the brooding stage.

The study, led by Dr Julian Finn of Museum Victoria in Melbourne, is the first to observe directly how this unique species of octopus captures air at the sea surface and uses it to its advantage.

"It wasn't until I actually got an argonaut in the water that I really saw the true marvel of these animals," said Dr Finn.

Unlike any other species of octopus, the female argonaut, which can be up to 50cm (20 inches) in length, makes itself a paper-thin shell. It secretes this shell, made of calcium carbonate, from two web structures on the sides of its body.

The males are much smaller, typically only a centimetre in length, and do not produce shells.

Mythical Creatures
Air pockets have been observed before within the shells of both wild and captive argonauts, also known as "paper nautiluses", but their origin and purpose has until now been a mystery.

"This mythical story began around the time of Aristotle that the argonaut female actually lived in the shell and raised those webs as sails as she sailed across the ocean," explained Dr Finn.

The new findings show that the female argonaut takes in air at the sea surface through a funnel as it rotates its shell anti-clockwise. It then seals off an air pocket in the top, or apex, of the shell using a second webbed pair of tentacles.

As it dives to depths of up to 750m (almost half a mile) below the surface, it adjusts the amount of air in its shell to match its own density with that of the seawater, keeping it "neutrally buoyant" and enabling it to swim effortlessly.

This contrasts with most other cephalopods - the class of animals that includes octopuses, squid and cuttlefish - which expend vast amounts of energy to maintain their position.

Underwater Control
The female argonaut can also counteract the considerable weight of its eggs, which it releases into its shell during the reproductive period, to carefully avoid bumping them on the sea floor.

By keeping a safe position in mid-water, argonauts can also steer clear of disturbance by surface waves and predators from above, such as birds.

Once believed to hinder the females, it is now thought that argonauts evolved this remarkable mechanism from ancestors that lived on the seafloor, allowing the species to expand its range into mid-depths.

"The female argonaut knows exactly what she was doing. Underwater she was completely in control," added Dr Finn.

Discovery LIFE Features the Octopus

From: SeattlePi.com, March 21, 2010
Written by: Tim Hall

Discovery LIFE

Discovery Channel's new series LIFE (hosted by Oprah Winfrey) begins Sunday March 21st at 8 PM. The first episode, Challenges of Life, shows what different species do to survive. Each species has a unique way of adapting to their ever changing environment...
The most fascinating part of the first episode was the octopus. The last act of the female octopus is laying 100,000 eggs (not a typo) and tending to them until they hatch. Shortly after she nurtures her eggs, she dies. I'm amazed at the level of sacrifice other animals possess.

To read the full article, please visit Blog.SeattlePi.com

LIFE, an 11-part series, debuts tonight, Sunday, March 21st at 8:00 pm.

Video: Lurking Octopus Makes Like an Umbrella

Very nice high quality video of an octopus lurking on a drilling platform. Once it's startled, it swims away. Great demonstration of how an octopus swims by jet propulsion.

Octopus Circulatory System

Here's a great article I found about the octopus's unique circulatory system on A Moment of Science.

When it comes to weird sea-creatures, octopuses are hard to beat. There's the well-known ink-squirting defense system, the bird-like beak, the eight tentacles with their double rows of suckers. What's less well known is that octopuses have more than one heart. They have three, to be exact, each one crucial to maintaining the robust blood pressure that allows octopuses to be active hunters and powerful swimmers.

Human hearts have two main jobs. One is to pump blood to the lungs, where it dumps carbon dioxide and picks up oxygen. The second is to distribute freshly oxygenated blood to the rest of the body. Making sure enough blood gets to the lungs is so important, in fact, that two of the human heart's four chambers are reserved solely for that task.

Octopus hearts solve the circulation problem a bit differently. They have one main heart, called the systemic heart, and two smaller hearts located near their gills. The two smaller hearts perform the same task as the right side of the human heart. They pump blood to the gills where it dumps waste and loads up on oxygen, then pump the oxygen-rich blood back to the main heart. The main heart then pumps the refreshed blood through the octopus's body.

Besides having three hearts, the octopus circulatory system differs from the human system in one other way. Humans blood contains the protein hemoglobin, which helps it absorb oxygen and causes its red color. The blood coursing through the three hearts of the octopus is blue, thanks to a different protein called hemocyanin.

Octopuses are rather shy, so despite their blue blood they are not exactly kings of the sea. But there's no denying that they've got a lot of heart.

Video: Octopus Swimming by Jet Propulsion

This brief video beautifully demonstrates how the octopus uses jet propulsion to get around.

Primitive Octopus Fossil: Pohlsepia Mazonensis

From: Tonmo.com
Written by: Phil Eyden, November 2004

Pohlsepia mazonensis was named after the person who discovered it, James Pohl, and the location, Mazon Creek. It is the earliest octopod that has been described to date and is approximately 296 million years old. Up until the recent discovery and publication of Pohlsepia in 2000 it was thought that the octopus lineage stemmed from the vampyromorphs sometime in the mid Jurassic, so it is obvious how important this discovery was of a soft-bodied octopod from the Upper Carboniferous (Pennsylvannian) as it pushed the origin of the octopus group back at least 140 million years further. It is important to remember that Pohlsepia clearly had its own ancestors and even at this early date had clearly defined cirrate-octopus features. The true origin of the octopods must have happened a few million years before even this remarkable fossil.

The fossil hails from the Upper Carboniferous deposits at Mazon Creek in Illinois, a source of extensive coal deposits. Many other cephalopods have been found in these deposits including nautiloids and the shelled torpedo-shaped ten-armed coleoid known as Jeletzkya. Specifically Pohlsepia comes from the Francis Creek Shale Member, this site of exceptional preservation consisted of rapid deposition of silt and sediments believed to have been at the mouth of a river delta where it met the sea. It is believed that storm surges following heavy rains swept masses of sediment down the river and out to sea burying coastal and marine animals and vegetation extremely rapidly. Concretions of ironstone then formed around the dead animals very quickly. Pohlsepia originates from the 'Essex' marine deposits and is preserved as a carbon film resembling a compressed stain inside one such nodule; this is typical for most fossils from Mazon Creek.


Just one example of Pohlsepia is known; as it is in a primitive condition the octopod actually has ten arms, two of these were modified but the other eight were approximately of the same length. The animal is small and is estimated to have had a Mantle Length of just 25mm long by 35mm wide. The animal lacks an internal shell much as with modern cirrate octopuses. The animal is sack shaped, has no clearly defined head and has very short arms. It also had two fins on its mantle, which are longer than they are wide, much like modern cirrate octopuses. The fossil has been preserved in a ventral aspect, eyes, a funnel, mandibles and a radula are identifiable and there is an indistinct feature that may represent an ink sac (extant cirrate octopods do not have these). No arm hooks or suckers are present. Peter Doyle and Joanne Kluessendorf published the fossil in 2000 and they have concluded that Pohlsepia should be assigned to the order Cirroctopoda.

Pohlsepia is housed at the Field Museum of Natural History, Chicago, Illinois.

How Does an Octopus Move?

The octopus has a few different modes of transportation available. The first of which is crawling. Octopuses sometimes travel along the ocean floor, or even in tide pools, and sometimes on land by walking on their arms.

It has been reported that octopuses can also travel by bi-pedal walking. Walking on two arms (or legs, if you will) is a slower more inconspicuous means of movements for the octopus. Both crawling and bi-pedal walking are safe modes of travel when there are predators nearby; crawling or walking allows the octopus to quickly escape a predator's clutches without drawing attention to itself. Often, when octopuses crawl or walk, they look like plants!

The movement that octopuses are often marveled at for is swimming by jet propulsion. This is the octopuses fastest means of locomotion. This process takes place by the octopus drawing water into a cavity in its body, then expelling the jet of water from a contractile mantle, and aiming it via a muscular siphon. The force of this squirting is so powerful that it moves the octopus swiftly backwards through the water. That is why octopuses swim headfirst, with their arms trailing behind.

An octopus using jet proplusion to swim over seagrass.

Octopus Inking Video

This 10-second video, filmed in the waters off Bolongo Bay in St. Thomas, demonstrates the octopuses brilliant defense mechanism known as inking.

This diver just got INK'D!!!

Octopus Inking: How Does it Work?

In addition to the octopus's uncanny ability to camouflage itself into its surroundings to avoid predators, the octopus has a secret weapon: ink. An ink sac is located near its digestive system, and when necessary, the octopus can eject ink out of the sac along with a burst of water from the funnel. The combination creates a black cloud. The octopus can shoot the ink out in little blobs that serve as decoys, or it can shoot it out in one big mass to obscure a quick getaway. To top it off, the ink contains tyrosinase, a compound that impairs smell and taste, which further confuses the predator.

Octopus Anatomy from Octopus.com, Part III

OCTOPUS SENSES
Octopuses have excellent sight, smell and touch. Each of their suckers has small and touch sensors capable of identifying even the smallest of scents or hints of a food source. They are however deaf with no auditory capability at all.
Their eyes slit-shaped pupils are well suited for the light levels which an octopus typically finds itself, but they do not appear to have color vision although they do distinguish polarization of light which may explain why they can mimic surrounding colors so well.

Two special organs called statocysts attached to the brain allow the octopus to orient its body and an autonomic response keeps the eyes oriented horizontally at all times.

Octopuses have an excellent sense of touch, and each sucker has chemoreceptors to allow it to taste what it touches. Each arm also contains tension sensors to allow it to know when they are stretched out but since each limb has some independent capability and the octopuses has very poor proprioceptive senses it is not always capable of determining the exact position of its body or arms at any given time. Due to this an octopus can’t tell the overall shape of an object it is handling (stereognosis) although it can detect texture variations on a local level.


The unique autonomy of the arms causes some difficulty for octopuses learning effects of its motions – to see what reaction the arms have taken to a high-level command means visually observing as there is no direct feedback to the brain from the arms themselves.

The neurological autonomy of the arms means that the octopus has great difficulty learning about the detailed effects of its motions. The brain may issue a high-level command to the arms, but the nerve cords in the arms execute the details. There is no neurological path for the brain to receive feedback about just how its command was executed by the arms; the only way it knows just what motions were made is by observing the arms visually.

Octopus Anatomy from Octopus.com, Part II

OCTOPUS DEFENSE
Octopus defense is primary avoidance and flight but they can bite with their sharp beak, have potent venom, in some cases enough to insure or kill a human, and are very strong. When threatened the Octopuses first reaction is normally to release Ink and initiate flight.

The ability to change skin color and mimic surrounding is a great avoidance/protection skill which they utilize in self preservation as well.

In addition to using their ink sacs and camouflage via the specialized skin cells, some octopuses can autotomise their limbs which will grow back. In the case of the Mimic Octopus there is also a fourth defensive option: mimicking more dangerous animals!

Mimic Octopus pretending to be something he's not!

Octopus Anatomy from Octopus.com, Part I

OCTOPUS PHYSIOLOGY
The donut-shaped brain of the octopus contains only part of its complex nervous system: at least two-thirds of an octopus’s neurons are actually located in the nerve cords of its arms. The arms themselves are boneless and highly flexible appendages which appear to have three excitatory neuronal inputs with fairly large synaptic input values.

Octopuses have no bone structure being invertebrates but do have a skull, a shell rudiment and a beak. Despite having no skeletal structure they are very strong and extremely flexible.

Octopuses have three hearts - one that pumps blue blood throughout their extensive vascular system similar to other molluscs, and two branchial hearts which pump blood to the gills for oxygenation.

Life Cycle of an Octopus

The first thing that happens to the octopus in the life cycle of an octopus is that it hatches from an egg. The young larval octopuses spend a period of time drifting in clouds of plankton, where they feed on copepods, larval crabs and larval starfish until they are ready to sink down to the bottom of the ocean, where the cycle repeats itself. In some deeper dwelling species, such as the Dumbo Octopus, the young do not go through this period. This is a dangerous time for the larval octopuses; as they become part of the plankton cloud they are vulnerable to many plankton eaters.

A juvenile octopus grows at a rapid rate, perhaps because of its short life span. Extremely effective at turning the food it eats into body mass, a young octopus increases its weight by 5 percent each day. By the end of its life, an octopus will weigh one-third as much as all the food it has eaten. Should a larval octopus be fortunate enough to survive this difficult period, it enters into the next stage of its life: it grows into an adult octopus.

Around the age of 1 or 2 years old, the full-grown octopus is ready to mate. When octopuses reproduce, males use a specialized arm called a hectocotylus to insert spermatophores (packets of sperm) into the female's mantle cavity. The hectocotylus in benthic octopuses is usually the third right arm. Males die within a few months of mating. In some species, the female octopus can keep the sperm alive inside her for weeks until her eggs are mature.

Blue-ringed octopus male and female mating; see the male inserting his reproductive tentacle into the female's funnel

After the eggs have been fertilized, the female lays about 200,000 eggs (this figure dramatically varies between families, genera, species and also individuals). The female hangs these eggs in strings from the ceiling of her lair, or individually attaches them to the substrate depending on the species. The female cares for the eggs, guarding them against predators, and gently blowing currents of water over them so that they get enough oxygen.

Photo of Giant Pacific Octopus eggs by Brandon Cole.

The female does not eat during the two to ten month period spent taking care of the unhatched eggs (Incubation period varies according to species and water temperature). At around the time the eggs hatch, the mother dies.

Then, we are back to the beginning of the life cycle of an octopus.

Eggs and one newborn Pacific Giant Octopus.

Cyanea Octopus in "The Great Escape!"

Because of their advanced problem-solving skills, dexterous mobility, and lack of a rigid skeletal structure, octopuses have the unique talent of being able to fit through tiny spaces. In this video, a 600 pound Cyanea Octopus wriggles it's way through an opening no bigger than a quarter! The footage is very high quality, offering a detailed view of the slippery tentacles as they maneuver through a clear plastic tube, and the narration is pretty darn informative. Enjoy:

How Many Arms Does an Octopus Have? Only Six - the Other Two Are Legs

From MailOnSunday.co.uk
Writen by Daily Mail Reporter

Ask anyone how many arms an octopus has and the usual answer will be eight. But scientists now insist these nautical animals only have six. In a new study they found that the creatures used six of their tentacles as arms and two as legs. Marine experts at 20 Sea Life centres across Europe gathered data from over 2,000 separate observations. They found common octopuses moved over the ground using their back two limbs, leaving the remaining six for eating.


(Above) Scientists found that octopuses use two tentacles for walking and four as arms.
Claire Little, a marine expert from the Weymouth Sea Life Centre in Dorset, said: 'We've found that octopuses effectively have six arms and two legs.

'It had been thought they used four tentacles for movement and the other four for feeding and manipulating objects.

'But observations showed that they use the rearmost two to get around over rocks and the seabed.

'They also use these two legs to push off when they wish to swim, and then other tentacles are used to propel them.'


Four legs up, two legs down: An octopus goes for a walk.
The results came out of a study designed to show if octopuses favoured one side or the other. The study had involved giving them jam jars and Rubik's Cubes to play with in a bid to see if the creatures favour a particular tentacle for handling objects.
While there is no obvious difference between any of the tentacles, experts were surprised to note how often the octopuses' third tentacle from the front was employed for eating.

They also concluded the creatures favour no side and are ambidextrous.

Octopus Sex More Sophisticated Than Arm-Wrestling, Part II

From Berkeley.edu

Written by Yasmin Anwar

Caldwell said most of what we know about octopuses comes from laboratory observations of just a few species that are summarized in books such as "Cephalopod Behavior" by Roger Hanlon and John Messenger (Cambridge University Press, 1996).

Because they are such bashful sea creatures, octopuses' mating rituals have been hard to get a handle on. "They're obsessively secretive, solitary and pretty spooky," Caldwell said. "If you watch them, they watch you back. It's hard to study them."

So, when UC Berkeley graduate Christine Huffard, now a postdoctoral fellow at the Monterey Bay Aquarium Research Institute in Moss Landing, Calif., discovered a thriving community of Abdopus aculeatus while doing her Ph.D. fieldwork in Sulawesi, she was overjoyed.

(Above) A male octopus's hectocotylus, or mating arm, (with pink lining) is inserted into the female's mantle.

"Each day in the water, we learned something new about octopus behavior, probably like what ornithologists must have gone through after the invention of binoculars," said Huffard, the study's lead author. "We quickly realized that Abdopus aculeatus broke all the 'rules' — doing the near opposite of every hypothesis we'd formed based on aquarium studies."

There are nearly 300 species of octopus in the world, ranging from the giant octopus in the Pacific Ocean to the tiny Octopus wolfi in the tropics. Mating is literally an octopus's life's work and can take place several times a day once the animal reaches sexual maturity. It usually begins with the male octopus poking the female with his long, flexible, hectocotylus arm and then slipping it into her mantle cavity.

Once the sperm packet has been deposited, the female retires to her den and lays tens of thousands of eggs, which she weaves into strings and attaches to the roof of her underwater dwelling. She keeps the eggs clean by blowing jets of water on them and is unable to leave her den to forage for food during this time. After about a month, the eggs hatch and the weakened mother octopus dies. The father also dies within a few months of mating, leaving the newborns to fend for themselves.

"It's not the sex that leads to death, Huffard said. It's just that octopuses produce offspring once during a very short lifespan of a year. And as the research team discovered, that once-in-a-lifetime lovemaking session is much more than just arm wrestling.

"This is the first study to show a level of sophistication not previously known in the sexual behavior of an octopus," Caldwell said. "We got it wrong before, and what this tells us is that we need to do a lot more fieldwork."