In biological classification, subspecies (abbreviated "subsp." or "ssp."; plural: "subspecies") is either a taxonomic rank subordinate to species, or a taxonomic unit in that rank. A subspecies cannot be recognized independently: a species will either be recognized as having no subspecies at all or at least two (including any that are extinct).

Under the International Code of Zoological Nomenclature, the subspecies is the only taxonomic rank below that of species that can receive a name. Under the International Code of Nomenclature for algae, fungi, and plants, other infraspecific ranks, such as variety may be named. In bacteriology, there are recommendations but not strict requirements for recognizing other important infraspecific ranks.

A taxonomist decides whether to recognize a subspecies or not. A common way to decide is that organisms belonging to different subspecies of the same species are capable of interbreeding and producing fertile offspring, but they do not usually interbreed in nature due to geographic isolation, sexual selection, or other factors. The differences between subspecies are usually less distinct than the differences between species.

The SPP-1 Underwater Pistol was made in the USSR for use underwater by Soviet frogmen as an underwater firearm. It was developed in the late 1960s and accepted for use in 1971. Underwater, ordinary-shaped bullets are inaccurate and very short-range. As a result, this pistol fires a round-based 4.5 millimetres (0.18 in) caliber steel dart about 115 millimetres (4.5 in) long, weighing 12.8 grams (0.45 oz), which has longer range and more penetrating power than speargun spears. The complete cartridge is 145 millimetres (5.7 in) long and weighs 17.5 grams (0.62 oz).

Design

The SPP-1 has four barrels, each containing one cartridge. Its ammunition comes as a magazine of four cartridges which is inserted into the pistol's breech.

Its barrel is not rifled; the fired projectile is kept in line by hydrodynamic effects. As a result, it is somewhat inaccurate when fired out of water.

A double-action firing mechanism fires one cartridge sequentially for each pull of the trigger. When all four cartridges are spent, the gun can be reloaded above or below water.

SSP is an abbreviation that may stand for:

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