The Octopus is an incredibly enigmatic creature that has fascinated scientists and storytellers for centuries due to its peculiar appearance and uncommon conduct.
It has become one of the most adored invertebrates in the ocean, and few creatures can match its mystique. Despite having blue blood, three hearts, and a brain shaped like a doughnut, these traits are not the most remarkable things about octopuses.
These creatures are recognized for their extraordinary appearance and exceptional intellect, and they continue to astonish us with their astonishing qualities, capabilities, and conduct.
Interesting Octopus Facts:
The Enormous and Diverse Size Range of Octopus Species:
The giant Pacific octopus is typically considered the largest octopus species, with adults weighing around 15 kg and an arm span of up to 4.3 m. The largest scientifically documented specimen had a live mass of 71 kg, while much larger sizes have been claimed.
The smallest species, Octopus wolfi, measures around 2.5 cm and weighs less than 1 g. Additionally, a carcass of the seven-arm octopus, Haliphron atlanticus, weighed 61 kg and was estimated to have had a live mass of 75 kg.
Cirrate and Incirrates: The Two Suborders of Octopuses:
In 1818, English biologist William Elford Leach coined the scientific name Octopoda and classified octopuses as Octopoida the year before. This order comprised approximately 300 recognized species and was traditionally categorized into two suborders – the Incirrina and the Cirrina.
However, recent findings suggest that Cirrina is not a distinct clade but rather the most basic species. The cirrate octopuses, which comprise most of the species, lack the cirri and paired swimming fins found in the crates. Furthermore, the incinerated internal shell is either absent or present in a pair of styles.
Bilateral Symmetry and Unique Features of Octopus:
The octopus has bilateral symmetry, with the head and foot at one end of an elongated body, and the foot evolved into prehensile arms surrounding the mouth. The arms are flexible and divided into four pairs based on position, with the two rear ones used for walking and the other six for foraging.
The mantle, fused to the head, is called the visceral hump and houses the most vital organs. The mantle cavity connects to the exterior by a funnel and contains gills. The octopus has a sharp, hard beak located underneath its arms.
The Octopus: A Creature of Remarkable Softness and Strength:
The octopus has skin consisting of a thin outer layer with mucous and sensory cells and a connective tissue dermis enabling color change. Its soft body is flexible, allowing it to lengthen, contract, and squeeze through small gaps.
The arms work as muscular hydrostats without skeletal support, containing muscles and a central nerve, which can extend, contract, twist, bend, or be held rigid in any direction.
Octopus Anchors Itself and Manipulates Objects with Circular Suckers:
The octopus has circular, adhesive suckers on the interior surfaces of its arms, allowing it to anchor itself or manipulate objects. Each sucker has an outer infundibulum and a central acetabulum, both covered in a protective cuticle.
The infundibulum is responsible for providing adhesion, while the acetabulum remains unattached, and muscle contractions enable the attachment and detachment of the sucker.
The arms can sense and respond to light, enabling the octopus to control them even when its head is hidden.
The visual system of octopuses:
The octopus has big eyes atop its head, encased in a cartilaginous capsule fused to the cranium.
Its cornea comprises a translucent epidermal layer, and its slit-shaped pupil lies behind the cornea. The eye’s retina is covered with photoreceptive cells, and the lens hangs behind the pupil.
The pupil can be modified in size, and retinal pigment functions to screen out incident light in bright environments.
The Cirrina’s Unique Features and Adaptations:
The body shape of some octopus species differs from the typical form. The Cirrina, which are basal species, have stout gelatinous bodies with webbing that extends near the tip of their arms.
Additionally, they have two large fins above their eyes, which are supported by an internal shell. Fleshy papillae or cirri are present along the underside of their arms, and their eyes are more developed.
The Dedicated Motherhood of Female Octopuses:
Female octopuses have the ability to lay as many as 400,000 eggs, which they tirelessly guard day and night, forsaking their meals.
The eggs typically take at least five months to hatch, but one deep-sea octopus was observed guarding her eggs for nearly 4.5 years. Once the eggs hatch, the female octopus will die soon after completing her mission.
The Deadly Sting of Australia’s Blue-Ringed Octopus:
The blue-ringed octopus, found in Australia, is widely acknowledged as one of the most venomous sea creatures on the planet.
Despite its small size of 5-8 inches, a single octopus possesses sufficient venom to eliminate 26 grown humans quickly. The potent venom of the octopus is loaded with tetrodotoxin, which is 1,200 times more deadly than cyanide.
The Intelligence of Octopuses: A Modern Reassessment:
In 350 BC, Aristotle wrote in his book “History of Animals” that octopuses were unintelligent creatures. However, recent studies have shown that they have advanced cognitive abilities and personalities, such as problem-solving, maze navigation, and dismantling objects for amusement.
Despite this, Aristotle’s description of octopus behavior in collecting and disposing of shells and fish skeletons remains accurate.
Octopus Arms: The Ultimate Multi-Taskers:
Octopuses’ arms are remarkable: they operate independently of the animal’s central nervous system. About two-thirds of the octopus’s neurons are in its arms instead of its brain, enabling them to solve in isolation.
This means an octopus can search for food while its arms crack open shellfish without requiring its brain’s attention. The arms can also respond even if they are disconnected from the body, as evidenced by an experiment in which detached arms flinched when pinched.
Octopuses: The Masters of Color and Pattern Change:
Octopuses are adept at concealing themselves and are solitary animals. They possess a muscular body comprising around 90% of their body mass, and their lack of bones enables them to squeeze through minute openings.
Their skin has specialized cells called chromatophores, which assist in changing their color and design. They are assumed to be intelligent animals that have the capacity to acquire knowledge, use tools, and recall locations.
The Evolutionary Strategies of Octopuses:
Octopuses can be found in every ocean, including along the coast of the United States. They prefer shallow coastal waters and live in small hollows and crevices in rocks and coral. Octopuses are solitary and territorial, facing many predators such as moray eels, fish, seals, whales, otters, and birds.
To avoid being hunted, octopuses use several strategies, such as changing their skin color, creating displays or releasing ink, hiding in crevices, and swimming quickly away.
The Feeding Behaviors of Octopuses:
Octopus hatchlings typically consume tiny organisms like copepods, larval crabs, and sea stars. In contrast, adult octopuses mainly rely on crabs, clams, snails, small fish, and occasionally, other octopuses as their food source.
Octopuses possess venom of varying degrees of potency in all species, which they administer through a beak that closely resembles that of a bird’s.
They usually hunt during the night, attacking their prey by suddenly jumping on them and trapping them in the webs between their arms and then piercing through the hard shells of their prey using their beaks.
Octopus’s Sensitivity to Pollution:
Octopuses are widely dispersed across vast stretches of the ocean and are known to live in isolation, making it challenging to assess their population levels accurately.
Although not currently believed to be endangered, octopuses are known to be sensitive to environmental pollutants. Additionally, researchers are continuously uncovering previously unknown species of octopuses.
Understanding Their Unique Respiratory System:
Octopuses breathe by drawing water into their mantle cavity, passing it through their gills, and expelling it through a siphon. The lamella structure of the gills allows for high oxygen uptake, and their skin can absorb additional oxygen.
An octopus can move by expelling water from its siphon, and water flow over the gills is related to locomotion. Connective tissue lattices support the respiratory muscles and allow for the expansion of the respiratory chamber.
The Anatomy and Physiology of the Octopus’s Ink Sac:
Octopuses have an ink sac situated beneath their digestive gland. This sac houses the ink produced by a gland attached to it. The proximity of the sac to the octopus’s funnel allows for the ink to be expelled with a water jet.
Before leaving the funnel, the ink is mixed with mucus from glands, creating a dense, dark substance that helps the animal evade predators. The ink’s primary coloring agent is melanin, which lends it a black hue. Ink sacs are typically absent in cirrate octopuses.
The Impact of Parasitic Diseases on Octopus Health and Survival:
Octopuses are known to be intermediate or final hosts for various parasites, including cestodes, nematodes, and copepods. One hundred fifty recognized species of protistan and metazoan parasites affect octopuses, including the Dicyemidae family of tiny worms found in renal appendages.
Some parasites, such as coccidian in the genus Aggregate, can cause severe disease to the host. Octopuses have an innate immune system, and their hemocytes respond to infection by attacking and destroying the pathogens. Vibrio lentus, a gram-negative bacterium, can cause skin lesions, muscle exposure, and sometimes death.
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