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  • Today Jonathan investigates the amazing world of suckers!

  • Cephalopods!

  • Welcome to Jonathan Bird's Blue World!

  • An octopus is on the prowl, looking for an unsuspecting fish to pounce upon.

  • A cuttlefish is hunting with mesmerizing colors to distract its prey.

  • A school of reef squid hover in the water column.

  • What do these magnificent animals have in common?

  • They are all cephalopods.

  • Cephalopod meanshead-footbecause this animal's head (the part with the eyes) is

  • connected to its feet.

  • The part out in front that looks like a head is actually the body.

  • And in fact biologists don't call those things feet, they are called arms.

  • So cephalopod is actually a terrible name, but it's what we have got.

  • Squid, octopods, cuttlefish and nautiluses are all members of the class cephalopoda,

  • but the really weird thing is that cephalopods are mollusks.

  • So they are related to animals like snails and clams, which seems a little crazy.

  • This is based mostly on their internal construction, not their outward appearance.

  • Perhaps the most obvious difference between most cephalopods and other mollusks is the

  • apparent lack of a shell.

  • The octopuses do not have shells at all.

  • The squid have a small internal shell.

  • Nautiluses are the only cephalopods with an external shell.

  • Nautiluses are found in the South Pacific and Indian oceans, typically in deep water.

  • Cephalopods have well-developed nervous systems, much more sophisticated than other mollusks.

  • And they can be quite inquisitive.

  • The cephalopod eye is one of the most notable examples of convergent evolution in all of

  • the animal world, because this eye evolved from completely different ancestors than the

  • eyes of mammals, yet it turned out to function in almost the exact same way.

  • Cephalopods, therefore, have extremely good eyesight.

  • Of course the most well-known of the cephalopods are the octopuses, named for their eight arms.

  • They are masters of disguise, able to change colors and skin patterns instantly.

  • With no shell, or bones the octopus can fit through tiny holes.

  • They make terrible pets because they can escape from virtually any aquarium!

  • The octopus has a mouth with a beak used to bite prey.

  • A hunting octopus often balloons over a rock to trap a fish.

  • Then it will use venomous saliva to kill the prey when it bites.

  • But the Blue-Ringed octopus of the South Pacific has venom so powerful that the bite of this

  • octopus is lethal to a human.

  • The mimic octopus is said to mimic other animals in order to hunt or evade predators.

  • This one has a convincing flounder imitation going on, but it's unclear how looking like

  • a flounder is advantageous.

  • It might just be the most efficient way to swim and stay camouflagedconvergent camouflage

  • if you will.

  • A coconut octopus in Indonesia carries a shell so that when the need arises, she can hop

  • inside and hide.

  • This clever behavior makes the octopus a tool user, putting her in a category of animals

  • considered more sophisticated and intelligent, like monkeys and dolphins.

  • In the cold water of Puget Sound, a Red Octopus is carrying a crab home for dinner, walking

  • on the tips of its arms.

  • That takes coordination!

  • Nearby, a

  • Giant Pacific Octopus breathes by drawing water into its mantle, a cavity in its body

  • and squirting it back out through a siphon.

  • Not only does this move water over the gills, but it gives the octopus the ability to squirt

  • water.

  • The siphon can be used for jet propulsion, squirting an octopus away at high speed.

  • A reef octopus in the Caribbean not only squirts away from me, but leaves a smoke screen behind

  • in the form of an ink cloud.

  • Squid and cuttlefish are similar to octopuses, but their small internal shell makes them

  • rigid and torpedo-like.

  • So, while the octopus often crawls along the bottom, the squid and cuttlefish like to jet.

  • In the North Atlantic Ocean, Longfin Squid cruise through the New England shallows.

  • But when they get annoyed by my camerathey can produce ink too.

  • More than 8 thousand miles away from New England, the waters of the Philippines are warm and

  • clear.

  • After the sun goes down, a Flamboyant cuttlefish comes out to hunt.

  • While the octopus has eight arms, the cuttlefish and squid actually have ten.

  • Eight of them are of the same length, while the other two are extra long, and used to

  • grab prey.

  • These two additional arms are called the tentacles.

  • Cuttlefish are often quite curious, and sometimes come right up to my camera for a look.

  • Their skin patterns change rapidly thanks to skin cells called chromatophores.

  • At the New England Aquarium in Boston, there's an exhibit where you can watch cuttlefish

  • up close.

  • And when you look carefully, you can see the chromatophores working.

  • At feeding time, the cuttlefish pay close attention, and they turn on the camouflage.

  • Then the cuttlefish strikes.

  • Even slowed down to one quarter speed, it's lighting fast.

  • With a high speed camera, a flamboyant cuttlefish blah blah

  • In another tank, a Giant Pacific Octopus guards it eggs.

  • All cephalopods lay eggs to reproduce.

  • Octopuses tend to guard their eggs.

  • Back in Indonesia, the Coconut octopus is releasing thousands of baby octopus hatchlings

  • from her clutch of eggs.

  • She carried them around for months while they incubated.

  • Squid and cuttlefish do no such thing.

  • The Atlantic Longfin squid lays its eggs like most squidcigar shaped bundles of eggs

  • attached to the rocks or kelp and left to fend for themselves!

  • The Flamboyant Cuttlefish eggs are about the size of a pea--laid on a rock.

  • Soon a baby cuttlefish is born.

  • The cephalopods are an amazing group of animals.

  • It's hard to imagine such advanced animals being closely related to such primitive mollusks

  • as the conch.

  • Cephalopods can change color and texture with chromatophores, they have extremely sharp

  • eyesight, multiple arms that are capable of complex tasks, and they are clever enough

  • to use tools!

  • They are definitely one of my favorite inhabitants of the Blue World.

Today Jonathan investigates the amazing world of suckers!

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スーパー吸血鬼。 頭足類!?| ジョナサン・バードのブルーワールド (Super Suckers: Cephalopods! | JONATHAN BIRD'S BLUE WORLD)

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    王杰 に公開 2021 年 01 月 14 日
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