User:Annabellebeaton/Giant Pacific octopus

Ideas for giant Pacific octopus


 * Movement and distribution patterns of the giant Pacific octopus
 * Raising of species in captivity
 * Seafood industry

Etymology
The giant Pacific octopus was first described in 1910 by Gerhard Wülker of Leipzig University in Über Japanische Cephalopoden. He describes the species' morphology in detail, and mentions that there seems to be much variation within the species. The specific name dofleini was chosen by Wülker in honor of German scientist Franz Theodor Doflein. It was moved to genus Enteroctopus by Eric Hochberg in 1998.

Movement Patterns
E. dofleini move through the open water using jet propulsion, which is achieved by drawing water into its body cavity and then forcefully expelling it through a siphon, creating a powerful thrust and propelling the octopus through the water at a high speed. When moving on the seafloor, however, the octopus crawls using its arms.

E. dofleini remain stationary or in hiding 94% of the time, usually concealed within dens, kelp, or camouflaged in their environment. Otherwise, they exhibit activity throughout the day, increasingly so from midnight to the early morning. While stationary, E. dofleini hide, groom, eat, sleep, and maintain dens. E. dofleini are capable of moving vast distances to occupy new areas or habitats, with large octopuses moving further than smaller ones. Their movements are not random; they demonstrate a preference for habitats with dense kelp cover and rocky terrain suggesting a sophisticated level of habitat selection, likely at optimizing foraging efficiency and minimizing exposure to predators. Furthermore, their movement patterns include direct relocations to new areas and central-tendency movements to return to familiar habitats. This navigation behavior is influenced by the use of familiar cliff edges, substrates, and topography as well as visual navigation.

E. dofleini migration patterns vary depending on the population. In the eastern Pacific waters off the coast of Japan, migration coincides with seasonal temperature changes in the winter and summer. Here, E. dofleini migrate to shallower waters in the early summer and winter and offshore in the late summer and winter. There is no evidence of these migration patterns in the Alaskan and northeast Pacific populations of E. dofleini.

Dens
E. dolfleini are den dwellers, which serve as a central point from when they forage while also providing protection, shelter, and privacy. After hunting, they bring food back to the den to feed in a safer environment and avoid predators. Shells, bones, and other feeding debris pile up outside of the den, creating "den litter" that is commonly used by scientists and divers to find E. dolfleini.

Dens range across depth and substratum type including caves, holes dug beneath rock, and even trash on the ocean floor such as bottles, tires, pipes, and barrels. Den selection is greatly influenced by foraging behavior and preferred pray. Dens made of soft substrata may be preferred in areas where bivalves are abundant while dens near rocky areas might be chosen in areas with higher crab populations. The size of the den is small, usually being just large enough for the octopus to fit inside and turn around. E. dolfleini beak size determines the size of the space it can fit inside, with its body being able to compress through tiny spaces as small as two inches. E. dolfleini prefer to occupy same shelter for at least one month, often longer if possible. It is common for these octopus to leave their den for short periods of time and eventually return to re-use the same den. However, over longer periods of time, E. dolfleini relocate to new dens situated relatively nearby, with an average distance of 13.2 meters.

Lifespan and reproduction (additions)
'[This section is well-developed, but needs some updates and corrections. Its organization could also be bettered, with moving of sentences and additional paragraph breaks. Italics represent the information already present in the articles. Regular text is my additions or corrections.]'

Unlike most other octopus species, whose lifespans normally span only one year, the giant Pacific octopus has a lifespan of three to five years. They reach sexual maturity at one to two years of age. Gonadal maturation has been linked to the optic gland of octopuses which has been compared functionally to the vertebrate pituitary gland. These optic glands are the only endocrine glands identified in octopuses, and their secretions have been found to contribute to behaviors linked with reproduction and senescence. When removed, females no longer brood their eggs, resume feeding, increase in weight, and experience longer lifespans compared to sexually mature, brooding females who still retain their optic glands.

To help compensate for its relatively short lifespan, the octopus is extremely prolific... During reproduction, the male octopus deposits a spermatophore (or sperm packet) more than 1 m (3.3 ft) long using his hectocotylus (specialized arm) in the female's mantle. The hectocotylus is found on the third arm of male octopuses and occupies the last four inches of the arm. This part of the male arm anatomy contains no suckers. Large spermatophores...laying fertilized eggs.

[FALSE STATEMENT FOR REMOVAL: Unlike males, only the female giant Pacific octopuses are semelparous, meaning they only breed a single time in their life.]

Both male and female giant Pacific octopuses are semelparous, meaning they only go through one breeding cycle in their life. Analysis of egg clutches has shown evidence of polygyny and polyandry in giant Pacific octopuses, where males and females mate with multiple partners. This multiple paternity potentially allows females to increase the odds of at least one of the males she mates with producing fit offspring. After mating, both the males and females stop eating and ultimately die. ''After reproduction, they enter a stage called senescence, which involves obvious changes in behavioir and appearance, including a reduced appetite, retraction of skin around the eyes giving them a more pronounced appearance, increased activity in uncoordinated patterns, and white lesions all over the body. While the duration of this stage is variable, it typically lasts about one to two months.'' Despite active senescence primarily occurring over this period immediately following reproduction, research has shown that changes related to senescence may begin as early as the onset of reproductive behavior. In early stages of senescence in E. dofleini, which begins as the octopus enters the stage of reproduction, hyper-sensitivty is noted where individuals overreact to both noxious and non-noxious touch. As they enter late senescence, insensitivity is observed along with the dramatic physical changes described above. Changes in sensitivity to touch are attributed decreasing cellular density in nerve and epithelial cells as the nervous system degrades. Death is typically attributed to starvation, as the females have stopped hunting in order to protect their eggs; males often spend more time in the open, making them more likely to be preyed upon.

The seafood industry
Current sentences: "The giant Pacific octopus has not been assessed by the Monterey Bay Aquarium Seafood Watch, although other octopus species are listed. (THIS SENTENCE IS NO LONGER TRUE)

''Combined with lack of assessment and mislabeling, tracking the species's abundance is nearly impossible. Scientists have relied on catch numbers to estimate stock abundance, but the animals are solitary and difficult to find."''

Fraud is an issue in the seafood industry, with species names being switched by accident or on purpose, as in the case of using the name of a more expensive species for a cheaper one. Cephalopods, in particular, lose distinguishing characteristics during food processing, making them much harder to identify. One study developed a multiplex PCR assay to distinguish between three prevalent octopus species in the Eastern Pacific, namely, the giant Pacific octopus, the big blue octopus, and the common octopus, in order to accurately identify these species and help to prevent seafood fraud. "Combined with lack of assessment and mislabeling, tracking the species's abundance is nearly impossible. Scientists have relied on catch numbers to estimate stock abundance, but the animals are solitary and difficult to find."

Sites like The Monterey Bay Aquarium Seafood Watch can help people to responsibly consume seafood, including the giant Pacific octopus. Seafood Watch lists giant Pacific octopus in either the "Buy" or "Buy, but be aware of concerns" categories depending on the geographical location of the catch.