The ninespine stickleback (''Pungitius pungitius''), also called the ten-spined stickleback, is a

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in the family

Gasterosteidae Families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of socie ...

that inhabits temperate waters. It is widely but locally distributed throughout

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

and

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. Despite its name, the number of spines can vary from 8 to 12.

Description

The body of the ninespine stickleback tapers to a very narrow caudal peduncle and the caudal fin is fan-shaped. The body is less deep and more elongated than that of the

three-spined stickleback The three-spined stickleback (''Gasterosteus aculeatus'') is a fish native to most inland and coastal waters north of 30°N. It has long been a subject of scientific study for many reasons. It shows great morphological variation throughout its ra ...

with a thinner and longer caudal peduncle, but the best way of distinguishing these two species is the number of spines in front of the dorsal fin which, for this species, varies from seven to twelve although nine is the commonest number. This species does not have scales but there is a group of small bony plates on the narrowest part of the caudal peduncle at the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

. The mouth points upwards in this species. It is generally greyish or olive-brown with silvery flanks irregularly barred or blotched with darker colour. During the breeding season, the males develop a black area around the pelvis and the pelvic spines become white. The eyes are dark with a gold ring around the pupils. The ninespine stickleback lives in streams, lakes, ponds and

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

s and favors thick submerged vegetation, as its small spines do not offer much protection. Like the three spined stickleback, they have a series of scutes or bony plates along the lateral line but, in freshwater populations, these are frequently reduced in number with a gap between the anterior and posterior plates.

Distribution

The species occurs in freshwater systems draining into the Arctic Ocean and the Atlantic across Canada and Alaska and south to New Jersey. It is present on the North American Pacific coast of Alaska and in the Great Lakes basin. It can also be found throughout most of Eurasia, including the United Kingdom,

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...

Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...

and the

Far East The ''Far East'' was a European term to refer to the geographical regions that includes East and Southeast Asia as well as the Russian Far East to a lesser extent. South Asia is sometimes also included for economic and cultural reasons. The ter ...

Behaviour

During the breeding season (April to July), the male builds a nest suspended on a piece of

waterweed ''Elodea'' is a genus of 6 species of aquatic plants often called the waterweeds described as a genus in 1803. Classified in the frog’s-bit family (Hydrocharitaceae), ''Elodea'' is native to the Americas and is also widely used as aquarium vege ...

, about an inch or so above the substrate at the bottom. The female is attracted by the male and she lays eggs inside the nest, but then departs, leaving parental care to the male. The male guards these eggs and the young fry when they hatch. Then, when they have their spines, he drives them away to look after themselves.

Physiology

The ninespine stickleback is a

euryhaline Euryhaline organisms are able to adapt to a wide range of salinities. An example of a euryhaline fish is the molly (''Poecilia sphenops'') which can live in fresh water, brackish water, or salt water. The green crab (''Carcinus maenas'') is an e ...

and

eurytherm A eurytherm is an organism, often an endotherm, that can function at a wide range of ambient temperatures. To be considered a eurytherm, all stages of an organism's life cycle must be considered, including juvenile and larval stages. These wide ...

al species of teleost fish, occupying both freshwater and marine habitats in higher latitudes of the world. Recently, this species has been under great examination due to pond populations' adaptations of morphology, life history, and behavior which separates them from their marine conspecifics. Many recently isolated populations (<11,000 years) have been studied to identify ranges of phenotypic plasticity and possible genetic drift between populations. It has been found that marine populations exhibit metabolic rate reduction when in colder conditions, in addition to having an elevated hepatosomatic index (HSI) at all temperature conditions as compared to freshwater populations in those same conditions. Hepatosomatic index refers to the proportional size of the liver of the fish to its body mass, as in indication of energy reserves. In addition, certain freshwater pond populations have shown to be able to metabolically compensate to survive a wide range of temperatures, six degrees Celsius to nineteen degrees Celsius. Alterations to metabolic rate, such as decrease in standard metabolic rate, allowed pond population individuals to survive less than favorable conditions. Such physiological differences between populations has not been determined to be exclusively due to plasticity or generic changes; however, there has been found to be significant genetic diversity between marine and freshwater populations. Due to their climatic versatility, Ninespine Stickleback face much variation in dissolved oxygen in their environment. Ninespines are physoclists, so they lack a connection between their swim bladder and their digestive tract. This means they cannot gulp air from the surface of the water, as physostome fish do, in order to compensate for an environment of low dissolved oxygen,

hypoxia Hypoxia means a lower than normal level of oxygen, and may refer to: Reduced or insufficient oxygen * Hypoxia (environmental), abnormally low oxygen content of the specific environment * Hypoxia (medical), abnormally low level of oxygen in the tis ...

. Responses to

may include increased ventilation rate or slower gill perfusion. Ninespines must rely solely on their gas secretion and absorption abilities, using aquatic surface respiration (ASR) when facing a hypoxic situation. Comparable physostomous fish could prevent ASR to an extent by gulping air, while Ninespines may only rely on only ASR when acclimating to hypoxic conditions. ASR is when the fish rise almost to the surface to ventilate with the top millimeter of water which is high in dissolved oxygen. Ninespine Stickleback do not regularly experience nocturnal hypoxia in their natural environments, and therefore, have slower and decreased control of their swim-bladder lift. Consequently, the Ninespines begin ASR at a much higher dissolved oxygen concentration in hypoxic environments, as compared to other stickleback species, such as the Brook Stickleback.

In culture

The celebrated British zoologist

Desmond Morris Desmond John Morris FLS ''hon. caus.'' (born 24 January 1928) is an English zoologist, ethologist and surrealist painter, as well as a popular author in human sociobiology. He is known for his 1967 book ''The Naked Ape'', and for his televisi ...

(born 1928) published a paper in 1952 — "Homosexuality in the ten-spined stickleback (''Pygosteus pungitius'' L.)." — which became the basis of his 1954 doctoral thesis at Oxford University. (This work was undertaken under the tutelage of the famous ethologist

Niko Tinbergen Nikolaas "Niko" Tinbergen (; ; 15 April 1907 – 21 December 1988) was a Dutch biologist and ornithologist who shared the 1973 Nobel Prize in Physiology or Medicine with Karl von Frisch and Konrad Lorenz for their discoveries concerning the or ...

.Von Hippel, Frank (editor), ''Tinbergen's Legacy in ''Behaviour'': Sixty Years of Landmark Stickleback Papers''; Leiden/Boston: Brill (2010), iii, 539 p. : ill., maps ; 25 cm.) Morris described and illustrated the normal reproductive behavior of the stickleback as well as certain "pseudofemale" variants which he thought might be fairly frequent in occurrence. ("These observations reveal that the nervous mechanisms of the sexual behavior pattern of the other sex are present, although they are not normally functional.") Although these findings were considered fairly conventional at the time within his specialty, the topic represented a harbinger of the later controversy that Morris's popular publications would arouse when he extended the findings of the biological sciences to the interpretation of aspects of human behavior. He describes some of his adventures with the fish, and his roomful of aquaria, in his book ''Animal Days'' (1979).

Description

Distribution

Behaviour

Physiology

In culture

References

Further reading