If you’re lucky enough, you may spot an octopus in an underwater den, beneath a rock, or inside a crevice on the sea floor of the Manuel Antonio National Park. They’re beautiful, and so exotic— and seem to be the alien prototype. Between the 8 legs, suction cups, changing colors, and bird-beak.

They’re weird.

So in order to understand the octopus, let’s take a look.

The Common Octopus.

There he is– up to 2 years, 4.3 feet, 22 pounds.

But this one’s a little more explanatory–

Octopus Diagram.

In order to better understand the octopus, let’s break him into body parts.

Octopus head.

1) Head. Soo that’s what you call an octopus head ——————>

Almost. Not quite. But we all know Davy Jones from Pirates of the Caribbean, and we all know he’s cunning. Just like the octopus– inside that bulbous head, lies a brain that generates the most intelligent of all invertebrates. Octopus have a cephalopod intelligence, in which they exhibit impressive spatial learning capacity, navigational abilities, and predatory techniques. The common octopus has learned to decipher lobster traps and steal the food inside; and to crawl aboard fishing boats and hide inside boxes of dead/dying crabs. Although octopus were evolved to change colors primarily for camouflage, squid (family member of the octopus) use color, patterns, and flashing in courtship and other communication practices. Possibly their most impressive form of intelligence– fort making. Octopus thrive in constructing shelters because of their ability to retrieve objects as a beforethought for later. The common octopus will retrieve an object and use it as a tool for later; for example, the veined octopus has been recorded retrieving coconut shells, manipulating them, and then transporting the shells for shelter construction. What sets octopus intelligence apart is the ability to pick up an object, transport it, and utilize it as a tool later.

Octo beak. 2) Beak. 
The beak is a tough muscle inside the head of an octopus– it feels and looks like bone, but it’s fingernail material. Octopus use their beak to break shells and tear flesh; inside the beak lies a radula, or barbed tongue, used to scrape animals out of their shell. The salivary papilla is a tooth-covered organ that drills into shells, eroding the material and weakening the prey. The salivary glands release a neurotoxin and enzymes to paralyze the animal, so it can be consumed and digested.

Now.. moving onto the Mantle. Just for clarification–

Octopus body parts.

3) Mantle. All you need to know about the mantle– it’s a big bag of vital organs. A highly muscled structure that protects the gills, heart, digestive system, and reproductive glands. The siphon is a hole that funnels water to the mantle cavity for locomotion, feeding, reproduction, and respiration purposes.

6) Arms.Dexterity, an ability essential for tool use and manipulation, is also found in cephalopods. The highly sensitive suction cups and prehensile arms of octopuses, squid, and cuttlefish are as effective at holding and manipulating objects as the human hand. However, unlike vertebrates, the motor skills of octopuses do not seem to depend upon mapping their body within their brains, as the ability to organize complex movements is not thought to be linked to particular arms. An octopus at the Sea Star Aquarium in Coburg, Germany named Otto was known to juggle his fellow tankmates around, as well as throwing rocks and smashing the aquarium glass. On more than one occasion he even caused short circuits by crawling out of his tank and shooting a jet of water at the overhead lamp.[5]