Common octopus
Common octopus Temporal range:
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Cephalopoda |
Order: | Octopoda |
Family: | Octopodidae |
Genus: | Octopus |
Species: | O. vulgaris
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Binomial name | |
Octopus vulgaris Cuvier, 1797
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Common octopus worldwide distribution | |
Synonyms | |
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The common octopus (Octopus vulgaris) is a mollusk belonging to the class Cephalopoda. Octopus vulgaris is one of the most studied of all octopus species, and also one of the most intelligent. It ranges from the eastern Atlantic, extends from the Mediterranean Sea and the southern coast of England, to the southern coast of South Africa. It also occurs off the Azores, Canary Islands, and Cape Verde Islands. The species is also common in the Western Atlantic.
Characteristics
Octopus vulgaris grows to 25 cm (10 inches) in mantle length with arms up to 1 m (3.3 feet) long.[3] It lives for 1–2 years and may weigh up to 9 kg (20 pounds).[4][5] Mating may become cannibalistic.[6] O. vulgaris is caught by bottom trawls on a huge scale off the northwestern coast of Africa. More than 20,000 tonnes (22,000 short tons) are harvested annually.[3]
The common octopus hunts at dusk. Crabs, crayfish, and bivalve mollusks (such as cockles) are preferred, although the octopus eats almost anything it can catch. It is able to change colour to blend in with its surroundings, and is able to jump upon any unwary prey that strays across its path. Using its beak, it is able to break into the shells of shelled mollusks. It also possesses venom to subdue its prey.[7]
They have evolved to have large nervous systems and brains. An individual has about 500 million neurons in its body, almost comparable to dogs. They are intelligent enough to distinguish brightness, navigate mazes, recognize individual people, learn how to unscrew a jar or raid lobster traps.[8][9][10] They have also been observed keeping "gardens", in which they collect various marine plant life and algae, alongside collections of shells and rocks; this behavior may have inspired the 1969 Beatles title, "Octopus' Garden". O. vulgaris was the first invertebrate animal protected by the Animals (Scientific Procedures) Act 1986 in the UK.[11] Training experiments have shown the common octopus can distinguish the brightness, size, shape, and horizontal or vertical orientation of objects.
Physiology
Habitat and demands
The common octopus has world wide distribution in tropical, subtropical and temperate waters throughout the world.[12][13][14] They prefer the floor of relatively shallow, rocky, coastal waters, often no deeper than 200 m (660 feet).[14] Although they prefer around 36 grams per liter (0.0013 lb/cu in), salinity throughout their global habitat is found to be between roughly 30 and 45 grams per liter (0.0011 and 0.0016 lb/cu in).[15] They are exposed to a wide variety of temperatures in their environments, but their preferred temperature ranges from about 15 to 16 °C (59 to 61 °F).[15] In especially warm seasons, the octopus can often be found deeper than usual to escape the warmer layers of water.[16] In moving vertically throughout the water, the octopus is subjected to various pressures and temperatures, which affect the concentration of oxygen available in the water.[15] This can be understood through Henry's law, which states that the concentration of a gas in a substance is proportional to pressure and solubility, which is influenced by temperature. These various discrepancies in oxygen availability introduce a requirement for regulation methods.[17]
Primarily, the octopus situates itself in a shelter where a minimal amount of its body is presented to the external water.[18] When it does move, most of the time it is along the ocean or sea floor, in which case the underside of the octopus is still obscured.[18] This crawling increases metabolic demands greatly, requiring they increase their oxygen intake by roughly 2.4 times the amount required for a resting octopus.[19] This increased demand is met by an increase in the stroke volume of the octopus' heart.[20]
The octopus does sometimes swim throughout the water, exposing itself completely.
Respiration
The octopus uses
The structure of the octopus' gills allows for a high amount of oxygen uptake; up to 65% in water at 20 °C (68 °F).
Water is pumped into the mantle cavity of the octopus, where it comes into contact with the internal gills. The water has a high concentration of oxygen compared to the blood returning from the veins, so oxygen diffuses into the blood. The tissues and muscles of the octopus use oxygen and release carbon dioxide when breaking down glucose in the
The gills are in direct contact with water – carrying more oxygen than the blood – that has been brought into the mantle cavity of the octopus. Gill capillaries are quite small and abundant, which creates an increased surface area that water can come into contact with, thus resulting in enhanced diffusion of oxygen into the blood. Some evidence indicates that lamellae and vessels within the lamellae on the gills contract to aid in propelling blood through the capillaries.[25]
Circulation
The octopus has three hearts, one main two-chambered heart charged with sending oxygenated blood to the body and two smaller branchial hearts, one next to each set of gills. The circulatory circuit sends oxygenated blood from the gills to the atrium of the systemic heart, then to its ventricle which pumps this blood to the rest of the body. Deoxygenated blood from the body goes to the branchial hearts which pump the blood across the gills to oxygenate it, and then the blood flows back to the systemic atrium for the process to begin again.[26] Three aortae leave the systemic heart, two minor ones (the abdominal aorta and the gonadal aorta) and one major one, the dorsal aorta which services most of the body.[27] The octopus also has large blood sinuses around its gut and behind its eyes that function as reserves in times of physiologic stress.[28]
The octopus' heart rate does not change significantly with exercise, though temporary cardiac arrest of the systemic heart can be induced by oxygen debt, almost any sudden stimulus, or mantle pressure during jet propulsion.[29] Its only compensation for exertion is through an increase in stroke volume of up to three times by the systemic heart,[29] which means it suffers an oxygen debt with almost any rapid movement.[29][30] The octopus is, however, able to control how much oxygen it pulls out of the water with each breath using receptors on its gills,[22] allowing it to keep its oxygen uptake constant over a range of oxygen pressures in the surrounding water.[29] The three hearts are also temperature and oxygen dependent and the beat rhythm of the three hearts are generally in phase with the two branchial hearts beating together followed by the systemic heart.[26] The Frank–Starling law also contributes to overall heart function, through contractility and stroke volume, since the total volume of blood vessels must be maintained, and must be kept relatively constant within the system for the heart to function properly.[31]
The blood of the octopus is composed of copper-rich hemocyanin, which is less efficient than the iron-rich hemoglobin of vertebrates, thus does not increase oxygen affinity to the same degree.[32] Oxygenated hemocyanin in the arteries binds to CO2, which is then released when the blood in the veins is deoxygenated. The release of CO2 into the blood causes it to acidify by forming carbonic acid.[33] The Bohr effect explains that carbon dioxide concentrations affect the blood pH and the release or intake of oxygen. The Krebs cycle uses the oxygen from the blood to break down glucose in active tissues or muscles and releases carbon dioxide as a waste product, which leads to more oxygen being released. Oxygen released into the tissues or muscles creates deoxygenated blood, which returns to the gills in veins. The two brachial hearts of the octopus pump blood from the veins through the gill capillaries. The newly oxygenated blood drains from the gill capillaries into the systemic heart, where it is then pumped back throughout the body.[26]
Blood volume in the octopus' body is about 3.5% of its body weight
Like those of vertebrates, octopus blood vessels are very elastic, with a resilience of 70% at physiologic pressures. They are primarily made of an elastic fiber called octopus arterial elastomer, with stiffer collagen fibers recruited at high pressure to help the vessel maintain its shape without over-stretching.[35] Shadwick and Nilsson[30] theorized that all octopus blood vessels may use smooth-muscle contractions to help move blood through the body, which would make sense in the context of them living under water with the attendant pressure.
The elasticity and contractile nature of the octopus aorta serves to smooth out the pulsing nature of blood flow from the heart as the pulses travel the length of the vessel, while the vena cava serves in an energy-storage capacity.
Osmoregulation
The
In terms of
O. vulgaris has a mollusc-style
Temperature and body size directly affect the oxygen consumption of O. vulgaris, which alters the rate of metabolism.
Within the renal sacs, two recognized and specific cells are responsible for the regulation of ions. The two kinds of cells are the lacuna-forming cells and the
One adaptation that O. vulgaris has is some direct control over its kidneys.[36] It is able to switch at will between the right or left kidney doing the bulk of the filtration, and can also regulate the filtration rate so that the rate does not increase when the animal's blood pressure goes up due to stress or exercise.[36] Some species of octopuses, including O. vulgaris, also have a duct that runs from the gonadal space into the branchial pericardium.[36] Wells[36] theorized that this duct, which is highly vascularized and innervated, may enable the reabsorption of important metabolites from the ovisac fluid of pregnant females by directing this fluid into the renal appendages.
Thermoregulation
As an oceanic organism, O. vulgaris experiences a temperature variance due to many factors, such as season, geographical location, and depth.[39] For example, octopuses living around Naples may experience a temperature of 25 °C (77 °F) in the summer and 15 °C (59 °F) in the winter.[39] These changes would occur quite gradually, however, and thus would not require any extreme regulation.
The common octopus is a
This implies that no real temperature gradient is seen between the organism and its environment, and the two are quickly equalized. If the octopus swims to a warmer locale, it gains heat from the surrounding water, and if it swims to colder surroundings, it loses heat in a similar fashion.O. vulgaris can apply behavioral changes to manage wide varieties of environmental temperatures. Respiration rate in octopods is temperature-sensitive – respiration increases with temperature.
As a temperature conformer,[43] O. vulgaris does not have any specific organ or structure dedicated to heat production or heat exchange. Like all animals, they produce heat as a result of ordinary metabolic processes such as digestion of food,[39] but take no special means to keep their body temperature within a certain range. Their preferred temperature directly reflects the temperature to which they are acclimated.[43] They have an acceptable ambient temperature range of 13–28 °C (55–82 °F),[43] with their optimum for maximum metabolic efficiency being about 20 °C (68 °F).[40]
As ectothermal animals, common octopuses are highly influenced by changes in temperature. All species have a thermal preference where they can function at their basal metabolic rate.[43] The low metabolic rate allows for rapid growth, thus these cephalopods mate as the water becomes closest to the preferential zone. Increasing temperatures cause an increase in oxygen consumption by O. vulgaris.[19] Increased oxygen consumption can be directly related to the metabolic rate, because the breakdown of molecules such as glucose requires an input of oxygen, as explained by the Krebs cycle. The amount of ammonia excreted conversely decreases with increasing temperature.[19] The decrease in ammonia being excreted is also related to the metabolism of the octopus due to its need to spend more energy as the temperature increases. Octopus vulgaris will reduce the amount of ammonia excreted in order to use the excess solutes that it would have otherwise excreted due to the increased metabolic rate. Octopuses do not regulate their internal temperatures until it reaches a threshold where they must begin to regulate to prevent death.[19] The increase in metabolic rate shown with increasing temperatures is likely due to the octopus swimming to shallower or deeper depths to stay within its preferential temperature zone.
Reproduction
Spawning of O. vulgaris in this area extends from December to September with a unique peak in spring months. [44]
See also
- My Octopus Teacher (2020 documentary film)
References
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- ^ "Octopus opens jar". YouTube. 16 September 2010. Archived from the original on 15 December 2021. Retrieved 5 February 2021.
- ^ "Octopus in prawn trap". YouTube. 12 February 2007. Archived from the original on 15 December 2021. Retrieved 24 April 2019.
- ^ Godfrey-Smith, Peter (2016). Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness. New York: Farrar, Straus and Giroux.
- ^ "The Animals (Scientific Procedures) Act(Amendment) Order 1993". 23 August 1993. Retrieved 22 February 2013.
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- ^ a b c d e Madan, J.J. & Wells, M.J. (1996). Cutaneous respiration in Octopus vulgaris. The Journal of Experimental Biology, 199: 2477–2483
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- ^ a b c d Wells, M.J., Duthie, G.G., Houlihan, D.F., Smith, P.J.S. & Wells, J. (1987). Blood flow and pressure changes in exercising octopuses (Octopus vulgaris). The Journal of Experimental Biology, 131, 175–187
- ^ a b c Young, Richard E. & Vecchione, Michael. (2002). Evolution of the gills in the octopodiformes. Bulletin of marine science. 71(2): 1003–1017
- ^ a b c d e f Wells, M.J., & Wells, J. (1995). The control of ventilatory and cardiac responses to changes in ambient oxygen tension and oxygen demand in Octopus. The Journal of Experimental Biology, 198, 1717–1727
- ^ Eno, N.C. (August 1994). The morphometrics of cephalopod gills. Journal of the Marine Biological Association of the United Kingdom, 74(3), 687–706
- ^ Melzner, F., Block, C. & Pörtner, H.O. (2006). Temperature-dependent oxygen extraction from the ventilatory current and the costs of ventilation in the cephalopod Sepia officinalis. Journal of Comparative Physiology B, 176, 607–621
- ^ Wells, M.J., & Smith, P.J.S. (1987). The performance of the octopus circulatory system: A triumph of engineering over design. Experientia, 43, 487–499
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- ^ Smith, P.J.S. (1981). The role of venous pressure in regulation of output from the heart of the octopus, Eledone cirrhosa (Lam.). The Journal of Experimental Biology, 93, 243–255
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- ^ a b c d e Wells, M.J. (1979). The heartbeat of Octopus vulgaris. The Journal of Experimental Biology, 78, 87–104
- ^ a b c d Shadwick, R.E., & Nilsson E.K.. (1990). The importance of vascular elasticity in the circulatory system of the cephalopod Octopus vulgaris. The Journal of Experimental Biology, 152, 471–484
- ^ a b c Hill, Richard W., Gordon A. Wyse, and Margaret Anderson. Animal Physiology. 3rd ed. Sunderland, MA: (635–636, 654–657, 671–672) Sinauer Associates, 2012. Print
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- ^ a b Katsanevakis, S., Protopapas, N., Miliou, H. & Verriopoulos, G. (2005). Effect of temperature on specific dynamic action in the common octopus, Octopus vulgaris (Cephalopoda). Marine Biology, 146, 733–738.
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- ^ a b c d Noyola, J., Caamal-Monsreal, C., Díaz, F., Re, D., Sánchez, A., & Rosas, C. (2013). Thermopreference, tolerance and metabolic rate of early stages juvenile Octopus maya acclimated to different temperatures. Journal of Thermal Biology, 38, 14–19.
- ^ Otero, González, Á. F., Sieiro, M. P., & Guerra, Á. (2007). Reproductive cycle and energy allocation of Octopus vulgaris in Galician waters, NE Atlantic. Fisheries Research, 85(1), 122–129. https://doi.org/10.1016/j.fishres.2007.01.007
External links
- Quinteiro, Javier; Baibai, Tarik; Oukhattar, Laila; Soukri, Abdelaziz; Seixas, Pablo; Rey-Méndez, Manuel (2011). "Multiple paternity in the common octopus Octopus vulgaris (Cuvier, 1797), as revealed by microsatellite DNA analysis" (PDF). Molluscan Research. 31 (1): 15–20. CiteSeerX 10.1.1.363.8342.
- "CephBase: Common octopus". Archived from the original on 17 August 2005.
- Photos of Common octopus on Sealife Collection