Blood squirt (blood spurt, blood spray, blood gush, or blood jet) is the effect when an artery, a blood vessel in the alive human body (or other organism's body) is ruptured. Blood pressure causes the blood to bleed out at a rapid, intermittent rate in a spray or jet, coinciding with the pulse, rather than the slower, but steady flow of venous bleeding. Also known as arterial bleeding, arterial spurting, or arterial gushing, the amount of blood loss can be copious, occur very rapidly, and can lead to death.
In cut carotid arteries with 100 mL of blood through the heart at each beat (at 65 beats a minute), a completely severed artery will spurt blood for about 30 seconds and the blood will not spurt much higher than the human head. If the artery is just nicked, on the other hand, the blood will spurt longer but will be coming out under pressure and spraying much further.
To prevent hand ischemia, there is a "squirt test" that involves squirting blood from the radial artery, which is used in intraoperative assessment of collateral arm blood flow before radial artery harvest. This is more commonly called "Allen's test" by microvascular surgeons, and is used before harvesting radial artery based free tissue transfers (cf Allen's test).
Chinnamasta, a self-decapitated Hindu goddess, is depicted holding her head with three jets of blood spurting out of her bleeding neck, which are drunk by her severed head and two attendants. Saint Miliau, a Christian martyr killed c. 6th century AD, is sometimes represented holding his severed head, as in the retable of the Passion of the Christ at Lampaul-Guimiliau, where blood gushes from his neck.
Some animals deliberately autohaemorrhage or squirt blood as a defense mechanism. Armored crickets, which are native to Namibia, South Africa, and Botswana, drive away predators by spewing vomit and spurting hemolymph (the mollusk and arthropod equivalent of blood) from under their legs and through slits in their exoskeleton. Katydids do it too, and in Germany the species has acquired the nickname "Blutspritzer", or "blood squirter". The regal horned lizard, too, uses the blood-spewing tactic, shooting the substance from a pocket near its eyes.
Squirting blood is used as a visual effect in anime, cartoons, comic books, film (mostly horror - particularly slasher - and action), literature, television series (mostly horror and drama), theater and video games.
The Monty Python sketch Sam Peckinpah's "Salad Days" (1972) involved an orgy of blood gushing, in a parody of Peckinpah's gore-filled directorial style. In Monty Python and the Holy Grail (1975), King Arthur must cut off all four limbs of the Black Knight to pass by in a forest, as the Knight bleeds on him.
Cormac McCarthy's 1985 novel Blood Meridian, Or the Evening Redness in the West includes a scene in which one of the two Jacksons decapitates the other by a campfire, leading to a graphically described blood spurt.
In the movie National Lampoon's European Vacation, Clark Griswold hits a cyclist with his car. Blood spews out of the cyclist's hand as he points to give directions.
The 1991 film Star Trek VI: The Undiscovered Country has a scene where a Klingon is shot ("phasered") in zero gravity. The blood that spurts out of the Klingon's wounds was created using computer generated imagery (CGI); the animators had to make sure that the blood floated in a convincing manner while still looking interesting and not too gory. The effects artist looked at NASA footage of floating water globules to match the physics of the blood particles.
Conan O'Brien has his head first spiked and then bitten off by two kraken-like sea monsters in the SyFy film, Sharktopus vs. Pteracuda (2014); his head continues to squirt copious amounts of blood as it is tossed by volleyball players.