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8 Octopus Facts (one for each arm)

There's absolutely no telling how many moms and dads have reached a point during this holiday season when they've thought, "I can't do everything at once. I'm not an octopus, y'know!" Well, having eight arms might sound like fun, but there's more to being an octopus than spitting out ink and attending Detroit Red Wings games. Here are 8 facts about these fascinating aquatic creatures that you may not have known. Enjoy!

1. All varieties of octopus are venomous.

oct1.jpgFortunately, only a few species have enough venom to injure or kill a human being. One of these is the blue ringed octopus, which is responsible for at least two confirmed deaths. Octopi inject their venom using a tough beak-like mouth that sticks out of the side of their head. It's similar to a bird's beak and is made of the same tough material as a lobster's shell.

2. A female octopus, known as a hen, may lay 100 thousand eggs...

...over its one-to-two-week fertile period. The transparent eggs are protected by the mother in the octopus' lair for several weeks. In most species, the eggs hatch, and the larval octopi swim for the surface where they may remain for a month or more. The vast majority of them die during this period. Weather and turbulent water get many of them, while others are swallowed up along with plankton by larger sea creatures.

3. An octopus' "ink" serves three important purposes.

Most - but not all - octopus species come equipped with an "ink sac" that spews out a stream of dark liquid into the water when the creature is threatened. When frightened, an octopus often "swallows" water with its body and ejects it forcefully. This not only propels the animal away from the danger, but also forces out a trail of "ink." This ink, which may be red, brown, or black, is made of melanin, the same dark pigment that colors human skin and hair. The ink's effects are three-fold: First, the initial "jet" of ink visually distracts, confuses, and perhaps even frightens the predator. Secondly, it may interfere with the predator's sense of smell or sight. And third, once dispersed, the ink clouds the water to help give the octopus time to escape.

4. An octopus' suckers are arranged in two rows down each arm

Some species have more suckers than others. And while some species grow a standard number of suckers on each arm by the time they become adults, the number of suckers on the arms of other species may vary. In some cases, female octopi have more suckers than the men, but only because of what "makes the male the male." Read on.

5. One arm of a male octopus is, well, special.

The third right arm, to be exact. At the tip of this "hectocotylus" arm is the ligula, which serves as its reproductive organ. In some species, the arm is visibly different since it has fewer suckers than the other seven arms. When a male fertilizes a female's eggs, she doesn't necessarily lay them right away. She may hold them for days or weeks before she feels ready to do so.

6. An octopus sees the same thing upside down as right-side up.

oct2.jpgThe large and complex eyes of an octopus help it to perform the two functions most necessary for survival: finding food and avoiding trouble. While most of the rest of the creature's body is quite flexible in the water, the eyes are more solid. As a result, some species of octopus can squeeze through tight spaces only slightly larger than their eyes.

Oddly, an octopus' eyes have horizontal pupils (in direct contrast to felines, whose eyes have vertical pupils). What's even more unusual is that the octopus' eyes remain at the same orientation regardless of the creature's position. So if it turns on its side or even upside down, the gaze of the eyes remain fixed in relation to the horizon.

7. Octopi don't like the spotlight.

Octopi like to keep hidden away. They'll usually find a cave or a formation in the rocks that allows them to remain secluded, but smaller octopi may hide inside a clamshell. They can actually crawl inside and use their suckers to pull the shell closed. Once the creatures get larger, however, they find clamshells are more interesting because they tend to include a tasty clam. A hungry octopus may perform any of a number of steps to open a clamshell. It may drill into the shell using its beak, it may use digestive juices to soften up the shell to break inside, or it may use its suckers and arms to pull the shell apart.

8. An octopus may also eat its own.

A hungry adult octopus isn't shy about consuming young octopi. After all, the smaller creatures can't put up much of a fight.

What's more, a study published in the March 2008 edition of Marine and Freshwater Behaviour and Physiology describes a female octopus that attacked, suffocated, and spent two days eating a male who'd just mated with her 13 times over a 3.5-hour period. And you thought your significant other was needy...

Happy holidays, everyone!

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Dodo: © Oxford University, Oxford University Museum of Natural History. Background: iStock
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science
Head Case: What the Only Soft Tissue Dodo Head in Existence Is Teaching Scientists About These Extinct Birds
Dodo: © Oxford University, Oxford University Museum of Natural History. Background: iStock
Dodo: © Oxford University, Oxford University Museum of Natural History. Background: iStock

Of all the recently extinct animals, none seems to excite the imagination quite like the dodo—a fact Mark Carnall has experienced firsthand. As one of two Life Collections Managers at the UK's Oxford University Museum of Natural History, he’s responsible for nearly 150,000 specimens, “basically all the dead animals excluding insects and fossils,” he tells Mental Floss via email. And that includes the only known soft tissue dodo head in existence.

“In the two and a bit years that I’ve been here, there’s been a steady flow of queries about the dodo from researchers, artists, the public, and the media,” he says. “This is the third interview about the dodo this week! It’s definitely one of the most popular specimens I look after.”

The dodo, or Raphus cucullatus, lived only on the island of Mauritius (and surrounding islets) in the Indian Ocean. First described by Vice Admiral Wybrand van Warwijck in 1598, it was extinct less than 100 years later (sailors' tales of the bird, coupled with its rapid extinction, made many doubt that the dodo was a real creature). Historians still debate the extent that humans ate them, but the flightless birds were easy prey for the predators, including rats and pigs, that sailors introduced to the isolated island of Mauritius. Because the dodo went extinct in the 1600s (the actual date is still widely debated), museum specimens are very, very rare. In fact, with the exception of subfossils—the dark skeletons on display at many museums—there are only three other known specimens, according to Carnall, “and one of those is missing.” (The fully feathered dodos you might have seen in museums? They're models, not actual zoological specimens.)

A man standing with a Dodo skeleton and a reconstructed model of the extinct bird
A subfossil (bone that has not been fully fossilized) Dodo skeleton and a reconstructed model of the extinct bird in a museum in Wales circa 1938.
Becker, Fox Photos/Getty Images

Since its extinction was confirmed in the 1800s, Raphus cucullatus has been an object of fascination: It’s been painted and drawn, written about and scientifically studied, and unfairly become synonymous with stupidity. Even now, more than 300 years since the last dodo walked the Earth, there’s still so much we don’t know about the bird—and Oxford’s specimen might be our greatest opportunity to unlock the mysteries surrounding how it behaved, how it lived, how it evolved, and how it died.

 
 

To put into context how old the dodo head is, consider this: From the rule of Oliver Cromwell to the reign of Queen Elizabeth II, it has been around—and it’s likely even older than that. Initially an entire bird (how exactly it was preserved is unclear), the specimen belonged to Elias Ashmole, who used his collections to found Oxford’s Ashmolean Museum in 1677. Before that, it belonged to John Tradescant the Elder and his son; a description of the collection from 1656 notes the specimen as “Dodar, from the Island Mauritius; it is not able to flie being so big.”

And that’s where the dodo’s provenance ends—beyond that, no one knows where or when the specimen came from. “Where the Tradescants got the dodo from has been the subject of some speculation,” Carnall says. “A number of live animals were brought back from Mauritius, but it’s not clear if this is one of [those animals].”

Initially, the specimen was just another one of many in the museum’s collections, and in 1755, most of the body was disposed of because of rot. But in the 19th century, when the extinction of the dodo was confirmed, there was suddenly renewed interest in what remained. Carnall writes on the museum’s blog that John Duncan, then the Keeper of the Ashmolean Museum, had a number of casts of the head made, which were sent to scientists and institutions like the British Museum and Royal College of Surgeons. Today, those casts—and casts of those casts—can be found around the world. (Carnall is actively trying to track them all down.)

The Oxford University Dodo head with scoleric bone and the skin on one side removed.
The Oxford University Dodo head with skin and sclerotic ring.
© Oxford University, Oxford University Museum of Natural History // Used with permission

In the 1840s, Sir Henry Acland, a doctor and teacher, dissected one side of the head to expose its skeleton, leaving the skin attached on the other side, for a book about the bird by Alexander Gordon Melville and H.E. Strickland called The dodo and its kindred; or, The history, affinities, and osteology of the dodo, solitaire, and other extinct birds of the islands Mauritius, Rodriguez and Bourbon. Published in 1848, “[It] brought together all the known accounts and depictions of the dodo,” Carnall says. The Dodo and its kindred further raised the dodo’s profile, and may have been what spurred schoolteacher George Clark to take a team to Mauritius, where they found the subfossil dodo remains that can be seen in many museums today.

Melville and Strickland described Oxford’s specimen—which they believed to be female—as being “in tolerable preservation ... The eyes still remain dried within the sockets, but the corneous extremity of the beak has perished, so that it scarcely exhibits that strongly hooked termination so conspicuous in all the original portraits. The deep transverse grooves are also visible, though less developed than in the paintings.”

Today, the specimen includes the head as well as the sclerotic ring (a bony feature found in the eyes of birds and lizards), a feather (which is mounted on a microscope slide), tissue samples, the foot skeleton, and scales from the foot. “Considering it’s been on display in collections and museums, pest eaten, dissected, sampled and handled by scientists for over 350 years,” Carnall says, “it’s in surprisingly good condition.”

 
 

There’s still much we don’t know about the dodo, and therefore a lot to learn. As the only soft tissue of a dodo known to exist, the head has been studied for centuries, and not always in ways that we would approve of today. “There was quite some consideration about dissecting the skin off of the head by Sir Henry Acland,” Carnall says. “Sadly there have also been some questionable permissions given, such as when [Melville] soaked the head in water to manipulate the skin and feel the bony structure. Excessive handling over the years has no doubt added to the wear of the specimen.”

Today, scientists who want to examine the head have to follow a standard protocol. “The first step is to get in touch with the museum with details about access requirements ... We deal with enquiries about our collections every single day,” Carnall says. “Depending on the study required, we try to mitigate damage and risk to specimens. For destructive sampling—where a tissue sample or bone sample is needed to be removed from the specimen and then destroyed for analysis—we weigh up the potential importance of the research and how it will be shared with the wider community.”

In other words: Do the potential scientific gains outweigh the risk to the specimen? “This,” Carnall says, “can be a tough decision to make.”

The head, which has been examined by evolutionary biologist Beth Shapiro and extinction expert Samuel Turvey as well as dodo experts Julian Hume and Jolyon Parish, has been key in many recent discoveries about the bird. “[It] has been used to understand what the dodo would have looked like, what it may have eaten, where it fits in with the bird evolutionary tree, island biogeography and of course, extinction,” Carnall says. In 2011, scientists took measurements from dodo remains—including the Oxford specimen—and revised the size of the bird from the iconic 50 pounder seen in paintings to an animal “similar to that of a large wild turkey.” DNA taken from specimen’s leg bone has shed light on how the dodo came to Mauritius and how it was related to other dodo-like birds on neighboring islands [PDF]. That DNA also revealed that the dodo’s closest living relative is the Nicobar pigeon [PDF].

A nicobar pigeon perched on a bowl of food.
A nicobar pigeon.
iStock

Even with those questions answered, there are a million more that scientists would like to answer about the dodo. “Were there other species—plants, parasites—that depended on the dodo?” Carnall asks. “What was the soft tissue like? ... How and when did the dodo and the related and also extinct Rodrigues solitaire colonize the Mascarene Islands? What were their brains like?”

 
 

Though it’s a rare specimen, and priceless by scientific standards, the dodo head is, in many ways, just like all the rest of the specimens in the museum’s collections. It’s stored in a standard archival quality box with acid-free tissue paper that’s changed regularly. (The box is getting upgraded to something that Carnall says is “slightly schmancier” because “it gets quite a bit of use, more so than the rest of the collection.”) “As for the specific storage, we store it in vault 249 and obviously turn the lasers off during the day,” Carnall jokes. “The passcode for the vault safe is 1234ABCD …”

According to Carnall, even though there are many scientific and cultural reasons why the dodo head is considered important, to him, it isn’t necessarily more important than any of the other 149,999 specimens he’s responsible for.

“Full disclosure: All museum specimens are equally important to collections managers,” he says. “It is a huge honor and a privilege to be responsible for this one particular specimen, but each and every specimen in the collection also has the power to contribute towards our knowledge of the natural world ... This week I was teaching about a species of Greek woodlouse and the molluscs of Oxfordshire. We know next to nothing about these animals—where they live, what they eat, the threats to them, and the predators that rely on them. The same is true of most living species, sadly. But on the upside, there’s so much work to be done!”

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