Graneledone boreopacifica is a species of octopus (Class Cephalopoda, Phylum Mollusca) that inhabits the benthic region of the Pacific Ocean. It does not currently have a common name. Relatively little is known about G. boreopacifica due to the extreme depth at which the species lives. Remote Operated Vehicles (ROVs) are needed to view G. boreopacifica in-situ. In addition, preserved specimens tend to break apart over time, contributing to our lack of information on the species (Voight, 2000a; Voight & Feldheim, 2009; and Voight, 2001). This octopus tends to stay within a couple degrees latitude of hydrothermal vents, where it nests and feeds (Voight, 2000a; Voight, 2000b; Voight and Grehan, 2000; and Onthank, 2013). G. boreopacifica is believed to be the most developed octopod upon hatching; it hatches after 4 year brooding period (Robinson et al., 2014; and Voight & Drazzen, 2004).
Since there are no good population estimates for G. boreopacifica there are no current conservation methods in place for the species.
G. boreopacifica is found solely in the Pacific Ocean from 36.22° S latitude and as far North as 43.66° N latitude (Keller et al., 2006). Based on collection samples, it is believed that females shift habitat preference upon reaching maturity (Voight & Grehan, 2000). Immature females are typically captured by trawl in areas of soft substrate whereas mature females are found in areas of hard substrate associated with potential locations of brooding octopuses (Voight & Grehan, 2000). Depths around 1050 m seem to be the peak depth for capture of G. boreopacifica, but they range in depth from 650 - 2600 m (Conners & Conrath, 2009, and Voight & Grehan, 2000).
As is typical of octopods, individuals of G. boreopacifica have eight arms. Their arms contain a single row of suckers, which is atypical when compared to the two rows of suckers found in other benthic octopods (Conners & Conrath, 2009). Each arm, excluding the arm that functions as the male copulatory organ (hectocotylus), contains 43 to 57 suckers; the hectocotylus contains either 42 or 43 suckers (Voight & Drazzen, 2004). The hectocotylus is a modification to one of the third arms (typically the right) in benthic species of octopods (Thompson & Voight, 2003). Along the ventral surface of the hectocotylus is a groove that terminates in a muscular projection and an arm tip that lacks suckers (Thompson & Voight, 2003). Compared to shallow-water species of octopus, G. boreopacifica has a more muscular ligula (terminal end of the male copulatory organ), and the hectocotylus is not muscularly different than the other 7 arms. These traits lead to the belief that the G. boreopacifica hectocotylus is more flexible compared to the hectocotylus of shallow-water species (Thompson & Voight, 2003).
G. boreopacifica also have a large beak and large beak adductor muscles, which are believed to aid in the consumption of whole gastropods (Voight, 2000a, and Voight 2013). The radula (a feeding structure typical in Mollusca) in members of the Graneledone genus is visibly shorter when compared to the radula of other benthic octopods (Voight, 2013). Due in part to the shorter radula of Graneledone, it is believed that the ingestion of food occurs differently in this genus (Voight, 2013). By the contraction of buccal abductors Graneledone can achieve an expanded volume of the posterior mouth. This characteristic allows it to passively draw in food along with moving water, thus relying less upon radular movement to bring in food (Voight, 2013).Members of the species are believed to have additional intestinal lining in order to prevent shards of gastropod shells from puncturing the brain (Voight, 2000a).
After dissection, specimens of G. boreopacifica are preserved in 70% ethanol solutions, and depending on the size of the specimen, stored mantle-down (large specimens) or arms down (Voight, 2001). The combination of mantle down storage and ethanol as the storage fluid leads to deformation in the genus Graneledone; the mantle-down storage causes a flattening of mantle, whereas the ethanol causes desiccation of fluid filled tissues, resulting in shrinkage in the mantle itself (Voight, 2001).
Because G. boreopacifica occurs in the deep-sea its population densities are not readily known (Voight personal communication).
In many benthic octopus species the third arm on either the left or right side (typically the right arm) is modified into the male copulatory organ, the hectocotylus (Thompson &Voight, 2003). The hectocotylus has a groove that runs the entirety of the ventral surface and terminates in a suckerless tip that is made up of the ligula (terminal end) and calamus (between the groove and ligula) (Thompson & Voight, 2003). Spermatophores are made in the male reproductive organ (located inside the mantle) and transferred to the hectocotylus, where the spermatophore is moved by peristaltic movement to the calamus and ligula (Thompson & Voight, 2003). The ligula containing the spermatophore is then inserted into the female’s reproductive organ which is located within the mantle cavity (Thompson & Voight, 2003). Unlike other cephalopod species, octopuses have complete internal fertilization within the female reproductive organ (Drew 1919).
In G. boreopacifica a single female can mate with several males before laying her eggs which can lead to multiple paternity among the brood (Voight & Feldheim, 2009).
Like many octopods, G. boreopacifica seeks out hard substrates onto which they attach their eggs to (Voight & Grehan, 2000). To allow for direct development of offspring, all known species of octopus sit on, or brood, their eggs (Robinson et al. 2014). In G. boreopacifica, individuals seem to choose areas near flows of cold water for better current exchange, where ambient temperatures are approximately 2°C. They also choose areas near hard substrates that are associated with hydrothermal vents (Drazen et al. 2003 and Voight & Grehan, 2000).
Brooding mothers of G. boreopacifica apparently will sit on their eggs for 54 months, based on the observation of one specimen visited from the time of substrate selection to the time when hatching occured (Robinson et al. 2014). When compared to shallow-water species, broods of G. boreopacifica have smaller clutches of larger eggs (Robinson et al. 2014 and Voight & Drazen, 2004). When analyzed using an equation for shallow-water species, eggs that measure 32 mm should be ready for hatching. However, G. boreopacifica eggs of 40 mm have yet to deplete their external or internal yolk sacs, indicating immaturity even at that larger size (Voight & Drazen, 2004). Individuals from eggs of 40 mm are deemed to be sub-adult due to the maturity of their reproductive organs, and the presence of internal yolk sacs (Voight & Drazen, 2004). In contrast, the sub-adult phase of shallow-water species typically occurs 3 months into the life cycle (Voight & Drazen, 2004). This apparent life-history trade off of a long brood period and low clutch size with larger egg size is believed to be an adaptation to deep-sea living that is used to minimize hatchling mortality by producing more highly developed offspring (Robinson et al. 2014 and Voight & Drazen, 2004).
G. boreopacifica has been shown to be an occasional hydrothermal vent predator, based on finding large portions of crushed shells of gastropods (Lepetodrilus fucensis) and mouth parts of polychaetes (Nereis piscesae), both of which are endemic to hydrothermic vents in the North Pacific Ocean (Voight, 2000a). It is believed that in locations of high sedimentation, G. boreopacifica will eat organisms that are buried in the sediment by sticking their arms into the sediment and moving material to the mouth (Voight, 2008). It is hypothesized that in areas of low sedimentation, G. boreopacifica will resort to predation in hydrothermal vents. It is unknown at present if the species is tolerant of high sulfide levels in vent habitats (Onthanks, 2013). The shift to vent predation may occur at maturity, when it has been shown that females of G. boreopacifica shift their habitat to areas of harder substrate (Voight & Grehan, 2000). Typically very little content is found in the gut of G. boreopacifica (Voight, 2008).
Graneledone boreopacifica is an octopus in the family Megaleledonidae. It can be found in both the Pacific and the Atlantic Oceans.
The holotype of this species measures 9 cm in mantle length.[2]
A female Graneledone boreopacifica was observed in the Monterey Canyon by the Monterey Bay Aquarium Research Institute, brooding her eggs for a record 53 months, making this the longest brooding or pregnancy period known in the animal kingdom. This also makes it the longest-living octopus – most octopuses only live for 1 or 2 years – which this octopus beats with its brooding period alone.[3][4] Female Graneledone boreopacifica tend to brood their eggs between the depths of 1,200 and 2,000 m; the eggs were never unattended.[5]
Examination of the gut of this octopus revealed significant amounts of crushed gastropod shells (Provanna variabilis and Lepetodrilus fucensis). The mandible muscles exhibit remarkable strength to crush the shells before digestion.[6]
Graneledone boreopacifica is found in benthic zones in temperate climates.[7]
The type specimen was collected in the Pacific Ocean (50°N, 151°E) and is deposited at the Zoological Institute in Saint Petersburg, Russia.[8]
Graneledone boreopacifica is an octopus in the family Megaleledonidae. It can be found in both the Pacific and the Atlantic Oceans.
