Octopuses Behavior: Sleep, Fighting, Personalities | Sea Life, Islands and Oceania

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OCTOPUS BEHAVIOR

20120518-octopus _-_NOAA_Photo_Library.jpg Octopus can slither into tight spaces and change shape to confuse predators. They can alter their colors to match their surroundings and squirt clouds of black ink to make an escape. Octopuses are bottom dwellers and are not found in open water. Although they may venture onto dry land in pursuit of a crab, if they remain there for more than half an hour they will die from suffocation. /=\

Octopuses are largely solitary creatures and spend much of their short lives in hiding. Most species hide in holes, crevasses and burrows during the day, often covering their hiding place with rocks, and hunt at night. They feed on shrimp, clams and crabs and other crustaceans and mollusks. With the exception of mating rituals, they live alone, concentrating on housing and feeding. They tend to be territorial (defend an area within the home range). If they encounter a member of their own species, there is always "psychological advantage" for the individual defending its own territory. If confrontation does lead to competition, octopuses attack competitors and rivals the same way they do with prey . [Source: Kelly Ray, Animal Diversity Web (ADW) /=]

Jennifer A. Mather wrote in Natural History magazine, “When I started my fieldwork on the behavior of juvenile common octopuses in Bermuda, I expected all my subjects to be much the same. I assumed their activities would be fairly limited; individuals would hunt, rest, and avoid predators, all in roughly the same way. In fact, I learned, their behavior is quite complex and variable. I watched as they carefully chose rocky crevices for their dens and blockaded the entrances with piles of rocks. I observed them navigate complicated routes across the sea bottom to and from their hunting grounds. But I was most intrigued to discover that individual octopuses are very different from one another. [Source: Jennifer A. Mather, Natural History, February 2007]

Around the same time, Roland C. Anderson, a marine biologist at the Seattle Aquarium,noticed that aquarium workers gave names to giant Pacific octopuses. The workers named the octopuses for their distinctive behaviors. Leisure Suit Larry, for instance, was all arms. He touched and groped his keepers so often that had he been a person, he would have been cited for inappropriate behavior. Emily Dickinson, by contrast, hid permanently behind the artificial backdrop of her display tank, so retiring that eventually she had to be replaced by a more active octopus for aquarium visitors to watch. Then there was Lucretia McEvil, whose caretakers were afraid to approach her, and who ripped up the interior of her tank. All those "characters" set me to thinking about whether octopuses might just have something like human personality.

Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems

Octopuses and Their Hiding Places

Common octopus (Octopus vulgaris)
Octopuses are rarely seen swimming around. They tend to hide in crevices amongst rocks, inside seashells, and discarded bottles and cans. Their soft-bodies are vulnerable to attacks from predators. They often place shells, rocks, hollowed-out legs of various crustaceans and human litter immediately in front of the openings to their lairs. They often occupy a particular hiding place for a long time and venture out only to hunt for food or look for a mate. However, they often can’t resist a new hiding place when one is offered that is why fishermen can catch them by dropping pots in the water. [Source: Kelly Ray, Animal Diversity Web (ADW) /=]

On the denning behavior of different octopuses, Jennifer A. Mather wrote in Natural History magazine: I could swear, for instance, that octopus number 45 never left its crevice — except that the discarded shells of clams, crabs, and snails kept appearing in front of the crevice. It must have been making secret hunting forays when my back was turned. By contrast, octopus number 26 was anything but shy. One afternoon I watched it as I floated in the shallow Bermuda water, hanging on to a rocky outcrop. The little octopus peered back at me from inside its den for some time, then suddenly jetted three or four feet directly toward me and landed on my dive glove. After about a minute of exploring, it must have decided the glove didn't taste good, and slowly jetted back home. I was hooked. [Source: Jennifer A. Mather, Natural History, February 2007]

Octopus Perception and Communication

Octopuses communicate with vision and touch and sense using vision and sound. According to Animal Diversity Web: In general, all octopuses have high-acuity-lens eyes on the sides of their heads. This placement forces them to use monocular vision, which means they only use one eye at a time. They are also color blind, but are able to distinguish between different hues and brightnesses. Octopuses respond to sound and use it as a way to find prey. [Source: Lindsey Lee, Animal Diversity Web (ADW) /=]

Octopuses have various ways of communicating among themselves. These organisms have a sender-receiver match (a species-specific vocalization) that allows them to communicate with each other. Octopuses use a complex skin display, using the chromatophores, to form patterns that other octopuses are able to comprehend. Another form of communication for these species are using their layers of iridocytes in the dermis of their skin, which produce reflections off the skin, signaling to other octopuses. Octopuses can also change the appearance of their skin and their posture, shaping their bodies into different patterns. These organisms use their advanced eyesight and tentacles, loaded with nerve endings, to perceive their environment./=\

Octopuses Feel Pain, Review Concludes

20110307-NOAA octopus_100.jpg A review of 300 studies published in scholars 2021 concluded there is strong evidence that some invertebrates — including crustaceans such as crabs, lobsters, shrimp, prawns, and crayfish, and cephalopods such as octopuses, squids, and cuttlefish — are sentient. The review defined sentience as "the capacity to have feelings, such as feelings of pain, pleasure, hunger, thirst, warmth, joy, comfort and excitement." The British government responded by updating it animal welfare laws with a bill to includes octopuses, crabs, and lobsters. [Source: Kelsey Vlamis, Business Insider, November 22, 2021]

An announcement said the bill "already recognizes all animals with a backbone (vertebrates) as sentient beings. However, unlike some other invertebrates (animals without a backbone), decapod crustaceans and cephalopods have complex central nervous systems, one of the key hallmarks of sentience." The decision followed the findings of a government-commissioned independent review by the London School of Economics and Political Science.

The review found there was "strong evidence" that such animals are sentient, which the review defines as having "the capacity to have feelings, such as feelings of pain, pleasure, hunger, thirst, warmth, joy, comfort and excitement." The report said there is no evidence of a slaughter method for creatures like octopuses that is "both humane and commercially viable on a large scale," recommending more research be done to identify more humane practices.

Octopus Sleep Like Humans— and Possibly Dream

In March 2021, scientists in Brazil published a study documenting evidence of a two-stage sleep pattern in octopuses animals, consisting of “active” and “quiet” sleep — similar to how humans fluctuate between rapid eye movement (REM) and non-REM sleep each night. In humans, most dreaming occurs during REM sleep, so some scientists wondered if octopuses might be able to dream during their “active” sleep stage. [Source: Live Science]

Will Dunham of Reuters writes: “The findings, the researchers said, provide fresh evidence that the octopus possesses a complex and sophisticated neurobiology that underlies an equally sophisticated behavioral repertoire, while also offering broader insight into the evolution of sleep, a crucial biological function. Octopuses previously were known to experience sleep and change colors while slumbering. In the new study, the researchers observed a species called Octopus insularis in a laboratory setting. They found that these color changes are associated with two distinct sleep states: "quiet sleep" and "active sleep." [Source: Will Dunham, Reuters, March 26, 2021]

“During "quiet sleep," the octopus remains still, with pale skin and eye pupils contracted to a slit. During "active sleep," it dynamically changes its skin color and texture and moves both eyes while contracting its suckers and body, with muscular twitches. A repeating cycle was observed during sleep. "Quiet sleep" typically lasted roughly seven minutes. The subsequent "active sleep" typically lasted less than a minute. This cycle appears analogous, the researchers said, to the alternating "rapid eye movement," or REM, and "non-rapid eye movement," or non-REM, sleep states experienced by people, as well as other mammals, birds and reptiles. Vivid dreaming occurs during REM sleep, as a person's eyes move rapidly, breathing becomes irregular, the heart rate increases and the muscles become paralyzed to not act out the dreams. Non-REM sleep features more deep sleep and less dreaming.

“Study lead author Sylvia Medeiros said the findings suggest octopuses may be dreaming, or experiencing something similar. “If octopuses indeed dream, it is unlikely that they experience complex symbolic plots like we do," said Medeiros, a doctoral student in neuroscience at the Brain Institute of the Federal University of Rio Grande do Norte. “'Active sleep' in the octopus has a very short duration, typically from a few seconds to one minute. If during this state there is any dreaming going on, it should be more like small video clips, or even GIFs," Medeiros added.

“Scientists are seeking a greater understanding of the origins and evolution of sleep. Because the last common ancestor of vertebrates, including humans, and cephalopods, including octopuses, lived more than half a billion years ago, it seems unlikely their similar sleep patterns were established before their evolutionary divergence, the researchers said. That would mean, they added, that this similar sleep pattern arose independently in the two groups, a phenomenon called "convergent evolution." “The investigation of sleep and dreaming in the octopus gives us a vantage point for the psychological and neurobiological comparison with vertebrates, since the octopus possesses several sophisticated cognitive features that are only seen in some vertebrate species but with a very different brain architecture," said study co-author Sidarta Ribeiro, founder of the Brain Institute. “The understanding of how organisms as different as humans and octopuses can share fundamental traits such as the sleep cycle opens new avenues for the investigation of animal cognition and for the understanding of the general principles that shaped brain design in these groups of highly intelligent animals," Medeiros said.

Octopus Having a Nightmare?

In May 2023, Live Science reported: Scientists have filmed an octopus exhibiting strange behaviors in a laboratory in New York that could be explained by it having nightmares. Over the course of a month, researchers watched as the octopus appeared to jolt out of a restful sleep and thrash around, in a behavior that seemed almost like the animal was suffering from some kind of sleep disorder. But was this octopus really having nightmares? There are some other potential explanations for why the animal might have acted this way, and experts expressed caution in interpreting the animal's behavior too quickly – but nonetheless, this behavior is certainly unusual. "For all the studies that have been done" on octopuses and other cephalopods, "there’s still so much we don't know," said Eric Angel Ramos, a postdoctoral researcher at the University of Vermont who helped film the octopus. [Source: Ethan Freedman, Live Science, May 22, 2023]

Video footage from a laboratory at The Rockefeller University in New York captured four episodes in which an Octopus insularis named Costello appeared to sleep calmly in a tank before suddenly flailing its tentacles around in a frenzy. In two of these instances, Costello also shot a jet of black ink into the water, a common predator-defense mechanism. "It was really bizarre, because it looked like he was in pain; it looked like he might have been suffering, for a moment," Ramos told Live Science. "And then he just got up like nothing had happened, and he resumed his day as normal."

Some of these behaviors are similar to what an octopus might do when encountering a predator in the wild, according to the research team, who described these behaviors in a preprint (which has not been peer-reviewed) posted to the server bioRxiv this month. That led the authors to speculate that “the animal may have been responding to a negative episodic memory or exhibiting a form of parasomnia,” meaning a sleep disorder. But they also cautioned that nothing can be definitively concluded from these observations.

However, one expert who wasn’t involved in the observations expressed caution in interpreting the octopus's actions as dreams. We don't know enough about the neuroscience of sleep in cephalopods to know if they dream at all, let alone have nightmares, Robyn Crook, a comparative neurobiologist at San Francisco State University, told Live Science. And even if octopuses do dream, they might dream in a completely different way than humans do, she said. “It's not something that we could easily answer,” Crook said. “It's a very philosophical question.”

So although the behaviors in this video are "very interesting," they could very likely have been spurred by something other than dreams, she said. For example, the octopus might have just been startled by something, Crook said. This octopus also might have been exhibiting signs of senescence, she said. This is the stage of an octopus’s life that occurs right before death, when their bodies start to break down.

In another octopus species, the giant Pacific octopus (Enteroctopus dofleini), Crook and her colleagues recently found an association between senescence and nervous system degradation. To her, the arm movements in the video seemed more like evidence of a lack of motor control, which she says is associated with senescence, rather than anti-predator behavior. Indeed, the species Costello belongs to lives for about 12 to 18 months, Ramos said, and Costello died shortly after these incidents. "I don't exclude that senescence could be one of the drivers of this," he told Live Science. It's possible that this behavior seemed unusual because many laboratory octopuses are euthanized before they start to senesce, Ramos said. Plus, most labs aren't filming their octopuses 24/7, he added, so other laboratories might have missed chances to spot similar behaviors.

Antisocial Octopuses

According to The Guardian: Under normal circumstances, octopuses are deeply antisocial, and treat each other with aggression –– sometimes to the point of eating each other. “Even during mating the male will just leave his sperm and depart as quickly as possible, because if he sticks around she’ll attack him,” said Gül Dölen, a neuroscientist at the Johns Hopkins University School of Medicine, who studies octopuses.

Gloomy octopus (Octopus tetricus) have been characterized as loners, with males and females meeting only once a year to mate and then dying. But sometimes they can be social such as in Jervis Bay on Australia's east coast but even then their interactions are often far from friendly. Live Science reported: In the site they have christened "Octlantis," an international team of marine biologists, led by Alaska Pacific University's David Scheel, observed "complex social interactions" among 10 to 15 octopuses on eight different days, as they foraged, mated and fought in close quarters. Their research, published online in September 2017 in the journal Marine and Freshwater Behaviour and Physiology, reveals an animal that is far from reclusive. In hours of footage recorded using four GoPro cameras, the octopuses are seen exhibiting threat displays and other signs of aggression, including violently ejecting one another from their dens. [Source: Jasmin Malik Chua, Live Science, October 30, 2017]

Faced with a would-be adversary, an octopus might darken its mantle to express its disgruntlement or splay itself lengthwise to appear larger. When going mano a mano — or tentacle to tentacle — one octopus might whip out its suckered arm to flail at another. It's a behavior that Stephanie Chancellor, a graduate student in biological sciences at the University of Illinois at Chicago and an author on the paper, said she found surprising. "I know these animals are intelligent, but this behavior — the communication, the grappling, all of them together — is very sophisticated," she told Live Science. "And it's pretty much unheard of with invertebrates."

As a community, Octlantis isn't unprecedented. In 2009, citizen scientist Matthew Lawrence and the University of Sydney's Peter Godfrey-Smith, both co-authors of the current paper, discovered a similar settlement a few hundred yards away. Dubbed "Octopolis," it housed several dens and featured one key difference: an unidentified metal object about 12 inches (30 centimeters) long, likely "garbage from a boat," Chancellor said. At the time, scientists thought that the settlement had formed as a result of the artificial object. But then Octlantis came along, with no similar item in place.

Fighting Octopuses Change Colour and Spread Their Arms

Footage shot by David Scheel, a marine biologist at Alaska Pacific University, off southeastern Australia suggests that Sydney octopuses broadcast their intentions to each other, either to avoid or to escalate conflict, by changing color.. National Geographic reported: The common Sydney octopus, also known as the gloomy octopus, were thought to be very independent: When they do come together to mate, the female often eats the male afterward. So the researchers were surprised that Sydney octopuses at their research site seemed to be interacting regularly. "The expectation has been that if two octopuses meet, the big one eats the smaller one," says Scheel, who presented the initial findings at a recent Animal Behavior Society meeting in Anchorage, Alaska. "But if octopuses encounter each other routinely, they can't cannibalize each other all the time." [Source: Mary Bates, National Geographic, July 14, 2015]

Instead, it makes sense that the octopuses would need to communicate to either escalate or avoid conflict—which is exactly what the team found. Scheel and his colleagues observed a range of aggressive interactions between octopuses—everything from simply reaching out toward another octopus, to chases, to grappling. Of all these incidents, only a fraction were full-blown fights. To get their point across, octopuses used a suite of dramatic behaviors such as spreading their arms wide, standing tall, raising their mantles—a structure that holds all their organs—like a crest above their eyes, and climbing on top of objects, the team observed.

The animals also changed color depending on their behavior: Aggressive octopuses tended to become darker, while fleeing octopuses were much paler. "If one octopus signals that he's coming over and not going to back down, and the other signals he is going to run away, that can end the interaction," says Scheel. "Whereas if they both signal that they're not going to back down, those are the [incidents] that tend to escalate."

Octopuses Throwing Stuff at Each Other

Underwater video cameras recorded over 100 instances of gloomy octopuses hurling silt and shells at one another in Jervis Bay, Australia in 2014 and 2015. The team of researchers that studied the behavior has published their findings in November 2022 in Plos One. Gizmodo reported: In the videos, the eight-armed cephalopods gather up material from the seafloor like silt and shells, and then push it through the water using their siphon and arms. Octopuses have previously been observed shooting sand from their siphon but never throwing more substantial objects like seashells. [Source: Isaac Schultz, Gizmodo, November 10, 2022]

The researchers found that the octopuses had to move their siphons into an unusual position — under the web of the octopus’ arms — to eject the material, indicating that they were intentionally throwing the material. The teams observed both sexes throwing material; about half of the throws were done while interacting with other octopuses. Only about 17 percent of the throws actually hit their targets. And if we’re splitting hairs, the octopuses are not hurling objects at their foes. The propulsion is entirely driven by their siphons; the arms are simply directing the material.

Because some of the throws were by male octopuses and some by female octopuses, and they occurred both in the presence and absence of other octopuses, the researchers aren’t exactly sure of the motive here. At least in some cases, the team believes the throws have a social purpose. And considering that in some of the videos the octopuses are literally blanketed in silt tossed at them by a nearby octopus, that seems correct.

In the abstract for the paper entitled “In the Line of Fire: Debris Throwing by Wild Octopuses,”
Peter Godfrey-Smith et al wrote: “Wild octopuses at an Australian site frequently propel shells, silt, and algae through the water by releasing these materials from their arms while creating a forceful jet from the siphon held under the arm web. These “throws” occur in several contexts, including interactions with conspecifics, and material thrown in conspecific contexts frequently hits other octopuses. Some throws appear to be targeted on other individuals and play a social role, as suggested by several kinds of evidence. Such throws were significantly more vigorous and more often used silt, rather than shells or algae, and high vigor throws were significantly more often accompanied by uniform or dark body patterns. Some throws were directed differently from beneath the arms and such throws were significantly more likely to hit other octopuses. Throws targeted at other individuals in the same population, as these appear to be, are the least common form of nonhuman throwing. [Source: Plos One, November 2022]

Paul the World Cup Octopus

Paul picks Spain over Germany
Paul the octopus was an unlikely star of the 2010 World Cup. He successfully predicted the outcome of eight matches—the results of all seven of Germany’s games, and finished by picking the tournament winner Spain, who defeated the Netherlands 1-0 in the final — from his aquarium at the Sea Life centre in Oberhausen. Germany [Source: BBC, October 26, 2010]

The BBC reported: “Paul made his name by successfully choosing a mussel from one of two boxes bearing the flags of competing nations. He correctly guessed the outcomes of seven of Germany's World Cup matches, including their defeats, and had "enthused people across every continent". As the tournament progressed, the octopus's uncanny knack of selecting the correct box drew increasing interest from the world's media, culminating in his choice of Spain as the eventual winner.”

Paul became an instant hero in Spain, prompting a request to have him put on display at Madrid zoo. Amid the euphoria, he was even made an honorary citizen of a Spanish town before being made an ambassador for England's 2018 World Cup bid. A documentary was filmed, and books and toys were made.

Paul died in October 2010, a few months after the World Cup. Octopuses rarely live beyond two years so his death was not unexpected. He was two-and-a-half years old and had been hatched at another centre at Weymouth in England in 2008. "It's a sad day. Paul was rather special but we managed to film Paul before he left this mortal earth," said his agent, Chris Davies said after his death.

Octopus Personality

Jennifer A. Mather studied the "personalities" of octopuses. She wrote in Natural History magazine, We gave "personality tests" to forty-four red octopuses (Octopus rubescens), natives of the West Coast of North America that weigh as much as a pound. We exposed each animal to three test conditions, seven times each, during a two-week period. We measured and recorded their responses when we opened the tank lid, when we touched them with a brush, and when we fed them a crab. The brush prompted the greatest variety of responses. Some octopuses grabbed it, stood their ground, and inflated their mantle to look bigger. Others jetted to the opposite end of the tank, leaving a cloud of obscuring dark ink in their wake. Individuals gave the same responses to the tests even after being exposed to them several times. [Source: Jennifer A. Mather, Natural History, February 2007]

20120518-octopus r_-_NOAA_Photo_Library.jpg
octopus with a badminton birdie
In all, the forty-four octopuses responded to the three tests with nineteen distinct behaviors. Statistical analysis enabled us to group the nineteen behaviors and place them along three personality dimensions: activity (how much the octopus moved around), reactivity (how strongly it reacted to the stimuli), and avoidance (how much it kept out of our way). An octopus could vary on all three dimensions independently. For example, among highly avoidant octopuses, which tended to remain in their dens during testing, some were extremely reactive, shrinking at the first sign of the brush. Others were not reactive at all, practically ignoring the brush. (By extension, Leisure Suit Larry, the touchy-feely giant Pacific octopus, would have rated high on activity and low on avoidance.)

So do octopuses have personality? Our answer is a qualified "yes." Because we didn't try to change their personalities by manipulating their experiences, we couldn't rule out the possibility that their behavioral variations might have been genetically preprogrammed. But given the octopus's legendary intelligence, behavioral flexibility, and learning ability, such preprogramming seems unlikely.

Octopus Personality Differences: Nature or Nurture

Jennifer A. Mather wrote in Natural History magazine, “How much of the behavioral differences among individual octopuses is inherited, and how much is learned? For his master's thesis, David L. Sinn, now a zoologist at the University of Tasmania in Hobart, raised laboratory-born California two-spot octopuses (Octopus bimaculoides) in small isolation chambers and gave juveniles the same three tests Anderson and I gave our red octopuses. The genetic effects were clear. Octopuses that shared at least a mother (female octopuses mate several times with any available male, so paternity was all but impossible to determine) reacted to the three tests more similarly than octopuses from different broods. Intriguingly, Sinn also discovered that as the animals matured, their responses to the tests changed in a predictable way. [Source: Jennifer A. Mather, Natural History, February 2007]

Sinn did not raise his subjects to maturity, so no one knows whether youthful experiences might have added a layer to the octopuses' temperaments to yield true adult personalities. It's too bad — it would be fascinating to know whether octopuses' differing experiences when young would result in differing adult personalities. Was Lucretia McEvil's destructiveness, for instance, the result of a "bad childhood"?

Another question about octopus personality is whether it has evolutionary benefits or drawbacks. The only scientific clue comes from Sinn's doctoral work, which showed that squid, too, vary along the personality dimensions of avoidance, activity, and reactivity. Shy female southern bobtail squid, Sinn found, mate with males that are shy, bold, or anything in between along the avoidance dimension. But bold females tend to reject shy males. Score one for the survival of the boldest. Sinn also found, however, that shy females are more successful than bold females at hatching their broods of eggs. No obvious pattern emerges, but personality clearly does affect survival and reproductive fitness.

Octopuses on Ecstasy

In 2018 scientists announced that they had given ecstasy (the drug MDMA) to octopuses and said the normally antisocial sea creatures becomes friendly and tactile after they took it. Gül Dölen, a neuroscientist at the Johns Hopkins University School of Medicine and the lead investigator on the study, said: “People are like, ‘Have you got any pictures of octopuses holding glow sticks?’ which I kind of ignore because that wasn’t really our objective. MDMA is a great tool for investigating whether or not an octopus can become social.” [Source: Hannah Devlin, September 20, 2018]

The Guardian reported: The answer was a definitive yes: the creatures’ normal hostility towards each other vanished and they became touchy-feely. The findings suggest that the brain chemical serotonin, which floods the brain after a dose of MDMA, has been a trigger for social behaviour since very early in evolutionary history.

The study, published in the journal Current Biology, studied the behaviour of octopuses in a tank with three connected chambers: one empty, one containing a plastic action figure, and a third with another octopus in a cage. Four octopuses were placed in a beaker of diluted MDMA, which they absorbed through their gills. While on the drug, all four spent far more time in the chamber with the caged octopus than they did without the drug.

The nature of their interactions were also strikingly different. Without MDMA, they approached the cage tentatively with just one tentacle outstretched. The drug made them relaxed and friendly. “They’re basically hugging the [cage] and exposing parts of their body that they don’t normally expose to another octopus,” said Dölen. There appeared to be other parallels with the euphoria experienced by people who take MDMA. “Some were being very playful, doing water acrobatics or spent time fondling the airstone [aquarium bubbler],” said Dölen. Others stretched out all eight arms and just floated around, doing what the researchers described as “water ballet”.

The findings are surprising because the octopus brain is radically different to our own: the central brain surrounds their throat and the majority of neurons, which appear to work semi-independently, are distributed through the arms. Until now, much research into the biology underpinning social behaviour has focused on sophisticated brain circuitry. The latest work suggests a more prominent role for basic brain chemistry, and in particular the brain chemical serotonin.

Image Sources: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated April 2023