Wednesday, November 9, 2011

Eight Coolest Octopus

Seperti semua cephalopoda, gurita adalah makhluk yang menakjubkan dan mempesona. Mereka adalah invertebrata yang paling cerdas, dan percobaan telah menunjukkan bahwa mereka memiliki memori jangka pendek dan jangka panjang dan dapat memecahkan teka-teki dan labirin. Sistem saraf gurita yang kompleks memberinya kemampuan refleks yang kilat, penglihatan yang tajam, dan kemampuan kamuflase yang luar biasa. Fosil gurita paling awal ditemukan pada periode Karbon sekitar 296 juta tahun yang lalu, dan hari ini ada sekitar 300 spesies yang dikenal. Gurita mendiami seluruh lautan dunia-dari laut dangkal sampai yang paling dalam. Berikut adalah delapan spesies gurita yang keren

1. Thaumoctopus Mimicus
The mimic octopus is one hell of a cool animal as these pictures and video show! Octopuses are thought to be one of the most intelligent invertebrates and can change the color and texture of their skin to blend in with rocks, algae, or coral to avoid predators. But until now, an octopus with the ability to actually assume the appearance of another animal had never been observed...Until now! You really should just watch the video. The typical coloration of a Mimic Octopus is white and reddish-brown stripes, and the they can grow up to 2 feet in length.

The Indonesian Mimic Octopus, Thaumoctopus mimicus. This fascinating creature was discovered in 1998 off the coast of Sulawesi in Indonesia, the mimic octopus is the first known species to take on the characteristics of multiple species. This octopus is able to copy the physical likeness and movement of more than fifteen different species" Nature keeps amazing.

The mimic octopus lives off the coast of Indonesia in shallow, open waters. That habitat differs from the more common octopus dwellings near coastal reefs or rocky ocean floors that provide an abundance of hiding places. Because of its relatively unprotected surroundings and its daytime foraging habits, the mimic octopus would be a sitting duck for local predators were it not for its many disguises.

Rather than just blending into the surrounding environment like many other octopuses, the mimic octopus takes on the form of venomous creatures. In particular, its lionfish and sea snake imitations are spot-on. A sea snake looks like any other snake you'd see on land with black and white banding. How does an eight-armed octopus do a believable snake impression? Coloration isn't a problem thanks to those pigment-filled chromatophores. Then, it simply tucks six of its legs into a hole and extends the remaining two. A lionfish, with its fan of poisonous spines, seems a little harder to pull off, but it's a cinch for the mimic octopus. The cephalopod compresses its head into the shape of the lionfish body and fans its tentacles around it like spines.

If this thing ever evolves to breathe air we are doomed

Proving the validity of the mimic octopus's imitations required hours of video and photographic documentation. Drawing conclusions about the intent behind the mimicry can be like two people cloud-gazing: One may see a bulldozer while the other makes out a dragon. However, the evidence gathered indicates a definitive method behind the mimic octopus's miming. For instance, researchers observing its actions found that the octopus only pulled out the sea snake impression in the presence of predatory damsel fish. Why is that significant? Sea snakes feed on damsel fish. Also, those two species are only a small sampling of mimic octopuses' masks. Experts also think they've witnessed up to 13 different species imitations, including jellyfish, anemone and mantis shrimp.

Even more intriguing than the mimicry action is the implied intelligence behind the behavior. It's well-established that octopuses have large brains in relation to their body size and are capable of learning. The mimicry is likely innate for the mimic octopus, but nevertheless requires the brainpower to recognize predatory species and know the appropriate form to take on. How exactly they picked up their broad repertoire of impersonations is still unknown.

Perhaps we've been seeing mimic octopuses for a long time but mistaking them for something else. Whatever the case, these masquerading masterminds of the deep have certainly made waves in the scientific community in their 10-year history.

2. Enteroctopus dofleini 
Common name: North Pacific Giant Octopus
Inhabiting the chilly waters of the northern Pacific is the mighty Enteroctopus dofleini. With a scientifically verified record weight of 71 kg (156.5 lb), it is generally considered the world’s largest octopus. (Although the rare Seven-Arm Octopus may hold a legitimate claim on that title.) A more typical size for an adult Giant Octopus is around 15 kg (33 lb), with an arm span of up to 4.3 m (14 ft)—still significantly larger than just about any other kind of octopus. Their diet consists of crustaceans, bivalves, and fish, and they have even been observed preying on sharks! With an average life span of 4-5 years, the North Pacific Giant Octopus is actually one of the longest lived octopus species.

3. Hapalochlaena sp.
Common name: Blue-ringed Octopus
The genus Hapalochlaena, which consists of at least three species, is found in tide pools across the western Pacific ocean. The common name of this octopus obviously comes from its striking coloration—blue rings (and stripes in one species) on bright yellow. It’s a good thing that these little octopuses are marked so vividly because they are one of the most venomous creatures in the world. Although it has been recently found that all octopuses (as well as cuttlefish, and some squid) are venomous, only the Blue-ringed Octopus is deadly to humans. Despite their tiny size (the largest species only grow to about 5 inches), a single individual contains enough venom to kill as many as 26 adult humans. For those unlucky enough to be bitten, death from respiratory paralysis and cardiac arrest can come in a matter of minutes, and there is no known antivenin.

4. Argonauta sp.
Common name: Argonaut, Paper Nautilus
Argonauts live in the open ocean in tropical and sub-tropical waters world-wide. Unlike most other kinds of octopus, Argonauts live near the surface, and in Classical times it was believed that they used their specialized shell-secreting arms as sails. It is their shells, which are actually egg cases produced by the female Argonaut, that give them their other common name: Paper Nautilus. Despite the uncanny visual similarity to the shells of the Chambered Nautilus and those of extinct ammonites, the Argonaut egg case is very different biologically (and mineralogically) from a true shell. Interestingly, the Chambered Nautilus was so named because of its apparent similarity to the Argonaut, even though we now consider the former to be the “true” Nautilus. There are at least six extant species of Argonaut, with several more known from the fossil record.

5. Grimpoteuthis sp.
Common name: Dumbo Octopus
Belonging to the Octopus suborder Cirrina, the genus Grimpoteuthis consists of over a dozen rare and poorly-known species, all of which are found in the extreme depths of the ocean. They are small, not getting much bigger than 20 cm (8 in), and their common name comes from the ear-like pair of fins (present in all cirrate octopuses, but generally larger in the Dumbos) which are used to assist locomotion the same way a squid uses its fins. Like other cirrate octopuses, the arms of the Dumbo Octopus are completely webbed, and they also retain an internal shell, something the more common incirrate octopuses (i.e. every other kind of octopus) have lost entirely. Dumbo Octopuses spend their time either sitting on the sea floor, or swimming just above it searching for food.

6. Amphioctopus marginatus
Common name: Coconut Octopus, Veined Octopus
Inhabiting sandy the bottoms of tropical lagoons of the western Pacific, A. marginatus often hides from potential predators by building itself a protective fortress out of debris from its environment. It seems to be particularly partial to coconut shells, and that’s the reason why one of its common names is the Coconut Octopus. (The other name is a reference to its dark vein-like color pattern.) In recent years, the Coconut Octopus has been observed walking bipedally. In one instance, one was seen to literally run across the sea floor on two arm while the rest of its body mimicked the shape and texture of a coconut! (The same report also includes a video of an individual of another species—Abdopus aculeatus—which was filmed walking backwards on two arms while adopting a posture reminiscent of floating algae.)

7. Tremoctopus sp.
Common name: Blanket Octopus
Behold the beautiful and otherworldly Blanket Octopus. Like the Argonauts (to which they are closely related), they live near the ocean’s surface, and can be found in both tropical and subtropical waters. There are four known species (the one depicted here is apparently T. gracilis, aka the Palmate Octopus), all of which share the same astounding anatomical and behavioral traits unique to this genus. Let’s begin with the name. As should be obvious from the image above, the female Blanket Octopus has two arms (the dorsal and dorsolateral, if you want to get technical about it) which are significantly longer than the rest and are connected to two other arms by a massive sheet-like membrane (the webbing is absent from the other four arms). It seems this “blanket” is unfurled when the animal feels threatened, presumably to make it appear bigger to any potential predator. Young individuals practice an altogether different defensive strategy. Apparently immune to the venom, they have been observed to carry pieces of the stinging tentacles of the Portuguese Man o’ War. The Blanket Octopus also exhibits one of the most extreme examples of sexual dimorphism of any animal: males, at 2.4 cm (or smaller), are minute, while the females can exceed 2 m in length.

8. Vulcanoctopus hydrothermalis
Common name: N/A
Vulcanoctopus is the only known cephalopod adapted to life in hostile hyrothermal vent environments. This little, and little-known, octopus lacks chromatophores (the specialized cells that give most octopuses the ability to change their color almost instantaneously) and pigment of any kind. Its eyes have greatly reduced functionality, perhaps even a complete loss of function, as they show no reaction to light when encountered in the wild. They are known to eat amphipods and have been observed hunting vent crabs.

Mungkin jika Gurita mempunyai usia yang cukup panjang, mereka akan membangun sebuah peradaban. dan jika mereka berevolusi sehingga dapat hidup didarat, maka manusia akan punah ... hehehehe


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