Three-spined stickleback
| Three-spined stickleback | |
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| Species: | G. aculeatus
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| Gasterosteus aculeatus Linnaeus, 1758
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The three-spined stickleback, Gasterosteus aculeatus, is native to much of northern Europe, northern Asia and North America. It has been introduced into parts of southern and central Europe.
Three subspecies are currently recognised.
- Gasterosteus aculeatus aculeatus is found in most of the species range, and is the subspecies most strictly termed the three-spined stickleback; its common name in England is the tiddler, although "tittlebat" is also sometimes used.
- G. a. williamsoni, the unarmored threespine stickleback, is found only in North America; its recognised range is southern California, though there are isolated reports of it occurring in British Columbia and Mexico;
- G. a. santaeannae, the Santa Ana stickleback, is also restricted to North America.
The three-spined stickleback reaches a maximum length of 11 cm. Many populations take 2 years to mature and experience only one breeding season before dying and some can take up to 3 years to reach maturity. However, some freshwater populations and populations at extreme latitudes can reach maturity in only 1 year. Although most specimens do have three spines on their backs, some have two or four; populations have also been identified in northern Scotland which are genetically 3-spined but actually lack spines. Three-spined sticklebacks can live in fresh, brackish or salt water. Fresh water varieties chiefly live in shallow inland ponds and streams but have also been found in the Great Lakes. They feed on worms, crustaceans, the larvae and adult forms of aquatic insects and drowned aerial insects, and small fish fry. They are in turn preyed on by larger fish, by fish-eating birds such as kingfishers and aquatic insects such as the dragonfly although their spines and the bony plates on their bodies serve as protection against many predators.
In spring, males defend territories where they build nests on the bottom of the pond or other body of water; the sequence of territorial, courtship and mating behaviours was described in detail by Niko Tinbergen in a landmark early study in ethology. Territorial males develop a red chin and belly colouration, and Tinbergen showed that the red colour acted as a simple sign stimulus, releasing aggression in other males and the first steps in the courtship sequence from gravid females. Red colouration is produced from carotenoids found in the diet of the fish. As carotenoids cannot be synthesised de novo, the degree of colouration gives an indication of male quality, with higher quality males showing more intense colouration. Males also develop blue irises on maturation. Only the males care for the eggs once they are fertilised. Parental care is intense, involving nest maintenance and fanning of the eggs to ensure a fresh water supply. Males build the nests from vegetation, sand, pebbles and other debris, adhering the nest together with spiggin, a proteinaceous glue-like substance secreted from the kidneys.
Sticklebacks are easily maintained in the aquarium, and are not currently considered to be endangered. They are popular subjects for laboratory research.
The three-spined stickleback was featured on a 14-franc postage stamp issued by Belgium in 1990.
It is also referred to in the very beginning of Dickens' "Pickwick Papers", in the title of Mr. Pickwicks illustrous work — "Speculations on the Source of the Hampstead Ponds, with some Observations on the Theory of Tittlebats".
References
- Froese, Rainer; Pauly, Daniel (eds.). "Gasterosteus aculeatus". FishBase. February 2006 version.
- "Gasterosteus aculeatus". Integrated Taxonomic Information System. 19 March.
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