Octopus – Classification, Morphology and Diagram

Octopuses live in marine habitats and are well known for their speed, intelligence, and camouflaging abilities. They are well known for their well-developed nervous system, distinct eight arms that bear suckers, and speed. To date around 300 species of octopuses have been identified and placed in the group of Cephalopods. Octopuses vary greatly in size.

In this article, we will study the taxonomic classification of the octopus, its habitat, diagram, anatomy, and reproduction of an octopus, behavior, and intelligence, its adaptations for survival, and conservation status and threats.

What is an Octopus?

Octopus is a soft-bodied organism classified under Phylum Mollusca. The largest known octopus species is the Giant Pacific Octopus (Enteroctopus dofleini) which can be around 5m tall while the smallest ones are O. arborescens that reach a length of about 5 cm only. Octopuses have a short life span that ranges between a few months to around 5 years and varies from species to species. Some species of Octopuses are also served as food in various cuisines.

Taxonomic Classification of Octopus

Below is the taxonomic classification of an Octopus:

Kingdom	Animalia
Phylum	Mollusca
Class	Cephalopoda
Order	Octapoda
Genus	Octopus

Where does an Octopus Live?

Octopuses are highly adaptable and live in a variety of marine environments, ranging from shallow coastal waters to deep regions of the ocean. Factors such as food availability, the presence of predators, and suitable locations for reproduction and shelter influence their choice of habitat. Some examples include:

• The California two-spot octopus (Octopus bimaculoides) is often found in reef environments along the California coast, where it can hide among rocks and crevices.
• The common octopus (Octopus vulgaris) is known to inhabit shallow coastal waters, including rocky shores and sandy bottoms, where it can prey on crustaceans and small fish.
• The dumbo octopus (Grimpoteuthis species) is a deep-sea octopus found in abyssal plains and other deep-sea environments.
• The blanket octopus (Tremoctopus) is a pelagic octopus that is found in open ocean waters.
• The sand octopus (Octopus kaurna) is adapted to sandy substrates and can bury itself in the sand for camouflage and hunting.

Diagram of an Octopus

Below is a labelled diagram of an octopus:

Morphology Characteristics of Octopus

Octopuses have a bilaterally symmetrical soft body well adapted to ensure their survival in the complex marine habitat. Some key morphological feature of Octopuses are given below:

• They have a sac like body that has a head with compound eyes and from its base arises eight contractile arms that have two rows of fleshy suckers that help in gripping and locomotion.
• The eight arms are united at their base and form the skirt.
• The mouth is located at the center of this skirt.
• Radula is a sharp file like organ inside the mouth and serves as the organ of chewing and biting.
• Like other mollusks, octopuses also have a mantle that unites posteriorly with the head.
• Mantle houses important organs like gills and helps in respiration by drawing in water and passing it through the gills.
• The mantle connects to the exterior through the syphon.
• The syphon is a funnel shaped structure that helps in propelling water to aid jet like motion.
• An ink gland in located near this syphon that secretes a paralyzing fluid that is propelled through the syphon during a defense act.

Reproduction in Octopus

Octopuses reproduce only once in their lives, thus exhibiting similarity. They are sexually reproducing organisms and exhibit advanced courtship, in which the males transfer the spermatophores with the help of specialised arms. Once the mating is complete, the female octopus lays eggs and guards them until they hatch.

During this time, she completely devotes herself to cleaning and aerating the eggs and hardly eats. This leads to rapid senescence and death after the eggs hatch. The eggs hatch to release paralysed larvae that undergo a developmental stage and turn into juvenile octopuses.

Behaviour and Intelligence

Octopuses possess a highly developed nervous system with a centralised brain. They exhibit complex behaviours, problem-solving skills, and learning capabilities. For example, some of the species, like veined octopuses, can manipulate objects like coconut shells as portable shelters and arrange stones to create defence barriers.

Octopuses also exhibit excellent memory and learning skills. Studies suggest that octopuses can remember individuals and adjust behaviours according to their learnings from past experiences. Several instances have been reported where octopuses have escaped complex setups like aquariums. 

Some Interesting Facts About Octopus

Some interesting facts about octopuses are listed below:

• Octopuses sense and taste through their suckers.
• Octopuses have remarkable regenerative abilities.
• Octopuses have three hearts. Two hearts pump blood to the gills, where it is oxygenated, while the third heart pumps the oxygenated blood to the rest of the body.

Conclusion: Octopus

Octopuses are interesting eight armed cephalopods that are considered to be the most intelligent invertebrates. They inhabit a large variety of marine environment and exhibit remarkable adaptability. They reproduce only once in their life time and generally die after their eggs hatch. They are well known for their speed and vision which makes them good hunters. Octopuses have the remarkable color changing abilities which is used by them to camouflage, communicate, and even in expressing their emotions.

FAQs on Octopus

How many Hearts does an Octopus have?

An octopus has three hearts. Two of these hearts pump blood to the gills and the third one pumps blood from gill to the other parts of the body.

Does Octopus have Teeth?

No, octopus do not have teeth. They have radula. It is a hard structure inside the mouth that helps in cutting and grinding.

Are Octopus friendly to Humans?

Octopuses have not been reported to be very social or friendly with humans. However, they have been reported to exhibit conditional bonding like curiosity on seeing a human and acting playful, certain level of interactivity with their caretakers when fed.

What makes Octopus Special?

Well developed nervous system, intelligence, excellent problem solving ability, camouflaging, mimicry, and defense mechanisms make octopuses special.

Why is it called an Octopus?

It is called an octopus because it has eight long arms. In Greek “oktō,” means “eight,” and “pous,” means “foot” or “leg.” Thus, the word octopus means eight legs.