Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey, Brainstuff, Lauren
Speaker 1: Bobblebaum here. But we humans are lucky that our sexual
Speaker 1: dimorphism is relatively mild. It certainly makes city planning easier.
Speaker 1: Consider the blanket octopus. A full grown male of the
Speaker 1: species is less than an inch long, only a couple
Speaker 1: of centimeters, and weighs less than a gram. The females
Speaker 1: can reach more than six feet or two meters in
Speaker 1: length and weigh one hundred pounds. That's forty five kilos.
Speaker 1: That means a female blanket octopus is some forty thousand
Speaker 1: times heavier than a male. In human terms, it would
Speaker 1: be like a man walking down the street with a
Speaker 1: woman who is four times the size of the Statue
Speaker 1: of Liberty, or a woman ringing up an order for
Speaker 1: a man the size of a beetle. Luckily, for the
Speaker 1: male blanket octopus, a mating is not a full contact sport.
Speaker 1: He has a modified arm that contains long rows of sperm.
Speaker 1: He simply tears off this arm and politely hands it
Speaker 1: to his mammoth mate, who then saves it for later use.
Speaker 1: These males have also been known to rip off the
Speaker 1: venomous tentacles of the Portuguese man O war and wield
Speaker 1: them as makeshift swords to ward off predators. This octopus
Speaker 1: is immune to the man o war's sting. And this
Speaker 1: is just one fascinating example of the octopod order, which
Speaker 1: contains over three hundred species, ranging in size from the
Speaker 1: quarter gram male blanket octopus to the six hundred pound
Speaker 1: plus giant Pacific octopus that's at least two hundred and
Speaker 1: seventy kilos. These invertebrates live only a few years, but
Speaker 1: they're seriously smart. They can camouflage themselves, solve puzzles, use tools,
Speaker 1: and even be sassy. Today, let's talk about octopuses, and yes,
Speaker 1: that is the scientifically preferred plural. The octopus belongs to
Speaker 1: the mollusk phylum, alongside slimy next of kin like clams, snails,
Speaker 1: and slugs. Within the phylum, octopuses are in the cephalopod class,
Speaker 1: which originated some six hundred million years ago and includes
Speaker 1: other advanced animals like squid and cuttlefish, but octopuses have
Speaker 1: evolved the most. While other cephalopods sport some form of
Speaker 1: inner or outer shell like their mollusc relatives, most octopuses
Speaker 1: have none. The word cephalopod means head footed. These animal's
Speaker 1: arms branch directly off of their heads. Some cephalopods have
Speaker 1: tentacles as well as arms, but the octopus manages just
Speaker 1: fine with the eight sucker studded arms it uses for
Speaker 1: practically everything, eating, moving, hunting, tasting, and mating. There are
Speaker 1: actually two suborders of octopus, the better known inserate and
Speaker 1: the more mysterious sirate. Serrate octopuses are named for the
Speaker 1: pairs of ccilia like strand along the suckers on their arms.
Speaker 1: They tend to live in deep cold water and don't
Speaker 1: adjust well to other conditions, meaning they're harder to study,
Speaker 1: though we've learned a lot about some species, like the
Speaker 1: dumbo octopus in recent years. Seriat octopuses do have a
Speaker 1: bit of an internal cartilage like shell. Both types of
Speaker 1: octopus will have a mouth at the center of its arms,
Speaker 1: and its doughnut shaped brain will sit just behind that,
Speaker 1: wrapped around the animal's esophagus sort of in the center
Speaker 1: of its body. That's where its two eyes are as well.
Speaker 1: The bulbous head of an octopus is actually what's called
Speaker 1: its mantle, a strongly muscled structure that protects the other
Speaker 1: organs its gills hearts. It has three hearts, digestive system
Speaker 1: and reproductive glands. Those three hearts come in handy because
Speaker 1: octopuses are adapted to survive in extreme temperatures and low
Speaker 1: oxygen environments. To cope, an octopus maintains a constant high
Speaker 1: blood pressure. Two of its hearts pump oxygen rich blood
Speaker 1: through the gills, while the third circulates it through the
Speaker 1: rest of the body. That blood is blue in color
Speaker 1: because it's copper based, not iron based like ours, which
Speaker 1: also makes it better at transporting oxygen in low temperatures.
Speaker 1: An octopus will also have a funnel, sometimes called a siphon,
Speaker 1: which is a tubular opening near the base of the
Speaker 1: mantle that serves as a jetway for water used for
Speaker 1: quick movement. Lacking a protective outer shell, the octopus has
Speaker 1: a startling array of defense mechanisms. They are masters of disguise.
Speaker 1: Cells in their skin called chromatophores, tens of thousands of
Speaker 1: them let them change color. These pigmented cells each contain
Speaker 1: three sacks of color and is surrounded by muscles that
Speaker 1: change how the pigment is displayed by relaxing or contracting
Speaker 1: it's sort of like a colorful design printed on a balloon.
Speaker 1: When the balloon is relaxed and uninflated, the design and
Speaker 1: its colors are smoothed and hidden. But when you stretch
Speaker 1: the balloon out by blowing it up, the colors become apparent,
Speaker 1: and you might be able to reveal different colors by
Speaker 1: expanding different parts of the balloon. The animal's nervous system
Speaker 1: can control each chromatophor independently, meaning color displays can be
Speaker 1: highly complex and quick. An octopus can change its appearance
Speaker 1: in less than a second. Also, areas on the skin
Speaker 1: called papilli can change size and texture from flat to
Speaker 1: bumpy to spiky to let the animal blend in with
Speaker 1: coral rocks, sand seaweed, and other stuff. The mimic octopus
Speaker 1: can even use color, shape, and movement to impersonate other animals.
Speaker 1: For example, it'll travel in a long, flatfish shape like
Speaker 1: the venomous banded soul, or wave an arm like a
Speaker 1: banded sea snake to make predators think twice about attacking
Speaker 1: and insert. Octopusses have another getaway mechanism, ink. The ink
Speaker 1: sack is located near the digestive system, and when necessary,
Speaker 1: the octopus can eject black ink out of the sack,
Speaker 1: along with the burst of water from its funnel, either
Speaker 1: in little blobs that serve as decoys, or in one
Speaker 1: bit mass like a smoke bomb, to obscure a quick getaway.
Speaker 1: The ink can also contain a compound that impairs smell
Speaker 1: and taste, to further confuse predators. Octopuses have excellent senses
Speaker 1: of sight and taste, partially because they have lots of
Speaker 1: processing power. An octopus's brain is proportionally larger than any
Speaker 1: other invertebrate, and smaller only than birds and mammals. The
Speaker 1: average octopus has as many neurons as a dog. Its
Speaker 1: central brain is only part of the story, though, Three
Speaker 1: fifths of the octopus's nerves are distributed throughout its arms
Speaker 1: to help it taste, touch, and move around its environment.
Speaker 1: Octopus arms are incredibly strong and flexible. Octopods have been
Speaker 1: known to wrestle sharks and break through plexiglass, and without
Speaker 1: all those pesky bones and joints that limit our movement,
Speaker 1: the arms have an almost infinite range of motion, and
Speaker 1: octopus arms have minds of their own. Literally, each has
Speaker 1: a cluster of nerve cells called a ganglion that works
Speaker 1: as a mini brain and allows the arm to act independently,
Speaker 1: though the central brain can take over. Our researchers think
Speaker 1: the brain can give an arm an assignment and then
Speaker 1: not have to think about it again unless something gets weird,
Speaker 1: like maybe the arm moves out of the water where
Speaker 1: it can no longer taste prey, so the octopus has
Speaker 1: to use its vision to guide the arm further. Next step,
Speaker 1: let's talk about octopus behavior. But first let's take a
Speaker 1: quick break for a word from our sponsors, and we're back.
Speaker 1: Thank you sponsors. Okay. Octopuses tend to spend much of
Speaker 1: their lives solitary in a den, leaving at night to hunt.
Speaker 1: An octopus might find a suitable den in a crevice
Speaker 1: or even a discarded bottle, or make one from objects
Speaker 1: like shells. When they do venture out, octopuses have a
Speaker 1: couple of ways to get around. If it needs to
Speaker 1: make a quick escape, it can jet away by taking
Speaker 1: water in through its mantle, sealing that water off, and
Speaker 1: then expelling it forcefully through its funnel. They've been clocked
Speaker 1: it up to twenty five miles an hour. That's forty
Speaker 1: kilometers an hour. Seriate Octopuses are less prolific at jetting,
Speaker 1: but they have a pair of fins coming off of
Speaker 1: their mantle that they can flap to move around. However,
Speaker 1: many octopuses prefer to walk along the seafloor with help
Speaker 1: from those rows of suckers on the underside of each arm.
Speaker 1: Each sucker has up to ten thousand sensory neurons, so
Speaker 1: the octopus can learn a lot about its surroundings this
Speaker 1: way and maybe chance upon a meal. Those long, flexible
Speaker 1: arms can reach into nooks after tasty crabs and clams,
Speaker 1: and their soft bodies are able to squeeze through tiny
Speaker 1: spaces after small fish. Octopuses don't have teeth as such
Speaker 1: to eat with, but they do have a hard, retractable
Speaker 1: beak similar in shape to a parrot's that can tear
Speaker 1: apart flesh or pry open shells. Behind the beak is
Speaker 1: the radula, which is a sort of barbed tongue the
Speaker 1: octopus can use to scrape meat out of a shell.
Speaker 1: It also has what's called a salivary papilla coming off
Speaker 1: of its salivary gland. This is a sort of secondary
Speaker 1: tongue with more toothy barbs that can drill through shell.
Speaker 1: The octopuses saliva can erode shell, and we can pray.
Speaker 1: In spite of being so clever and well built, octopuses
Speaker 1: only live an average of three to five years. Most
Speaker 1: will mate only once in their life and die soon afterwards,
Speaker 1: the male after a few months and the female after
Speaker 1: her eggs hatch. Not all of them detach an arm
Speaker 1: in the mating process, though the males do tend to
Speaker 1: have a modified arm for holding sperm. Either way, once
Speaker 1: the female receives sperm, she lays her eggs or applies
Speaker 1: it to her laid eggs if she's been saving a
Speaker 1: stray arm for the occasion. The female often cares meticulously
Speaker 1: for her eggs until they hatch, blowing water across them
Speaker 1: to keep them clean and protecting them from predators. The
Speaker 1: eggs might incubate from two to ten months or more,
Speaker 1: depending on the species and water temperature. Sometimes the female
Speaker 1: will forego eating to protect them, so once they hatch,
Speaker 1: there on their own. If it manages to survive predation,
Speaker 1: a young octopus may eat enough to increase its weight
Speaker 1: by five percent every day. After all, it doesn't have
Speaker 1: time to lose. And let's talk about those smarts. Octopuses
Speaker 1: are capable of thought, typically only observed in primates, and
Speaker 1: select other animals like crows in the wild. The giant
Speaker 1: Pacific octopus has been seen stealing crabs caught in traps
Speaker 1: by human fissures before the fissures can pull in their hull.
Speaker 1: The Pacific striped octopus uses a goatchia to catch shrimp.
Speaker 1: It'll sneak an arm around to poke the shrimp from
Speaker 1: one side, awaiting in the opposite direction to grab the
Speaker 1: shrimp when it darts away. The veined octopus is known
Speaker 1: to collect coconut shells and seashells, clean them off with
Speaker 1: jets of water, and carry them elsewhere to assemble a shelter.
Speaker 1: In captivity, octopuses have learned to solve mazes and puzzles
Speaker 1: and complete tasks to receive tasty rewards. They've been known
Speaker 1: to crawl out of their aquariums to sneak food from
Speaker 1: bins or other tanks, and then return to their home
Speaker 1: tank unassisted. Some can crawl across dry land for a
Speaker 1: limited period of time. Octopuses can recognize different humans faces
Speaker 1: and will react differently to them. There is an anecdote
Speaker 1: out of a University in New Zealand, where an octopus
Speaker 1: apparently took umbrage to one of the members of the
Speaker 1: staff and would squirt water at her every time she
Speaker 1: passed the tank. In another incident out of Pennsylvania, a
Speaker 1: researcher attempted to feed slightly stale squid to the octopuses
Speaker 1: in her lab, and one sent her a clear message.
Speaker 1: It made eye contact and used one arm to shove
Speaker 1: the squid down a nearby drain, effectively communicating that stale
Speaker 1: food would be discarded rather than eaten. Any animal that's
Speaker 1: smart enough to be a little rude is definitely impressive.
Speaker 1: The researchers are even looking into how we humans can
Speaker 1: mimic some of octopus's superpowers to build everything from better
Speaker 1: camouflage materials to soft, squishy robots. Today's episode based on
Speaker 1: the articles how Octopuses Work by Jennifer Horton and why
Speaker 1: is Octopus Blood Blue? Written by Lareel Dove on HowStuffWorks
Speaker 1: dot Com. A Brainstuff is production of iHeartRadio in partnership
Speaker 1: with HowStuffWorks dot Com and is produced by Tyler Klang.
Speaker 1: For more podcasts from my heart Radio, visit the iHeartRadio
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