ostracods disturbed by moving prey. This species' visual system is attuned to the wavelengths of light emitted by these planktonic organisms, showing the importance of night hunting. Pacific angelsharks are more likely to strike at prey approaching from the front. It usually waits until the prey approaches to , as its attack is less accurate beyond this distance. The strike is a stereotyped behavior in which the shark presses the forward lobes of its pectoral fins against the bottom and thrusts its head upwards at up to a 90° angle. Its mouth forms a tube when opened, creating a suction force, while its jaws protrude forward to secure the prey between sharp teeth. During the strike, the eyes roll backward into the head for protection. The strike is often completed in under a tenth of a second. Life cycle The Pacific angelshark is aplacental viviparous with the unborn young nourished by a yolk sac; reproduction occurs on an annual cycle. Most females have a single functional ovary (on the left side), though some have two; the oviducts are often filled with yolk, which is speculated to be from the resorption of unfertilized eggs. At long, the young embryos have translucent skin, protruding eyes, and exposed gill filaments. Spots of pigment have developed when the embryo is long, and the first row of teeth has appeared when the embryo is long. By the time the embryo is long, the mouth has migrated to a terminal position and the color pattern has fully developed; the external yolk sac begins to shrink as the yolk is transferred to an internal yolk sac, where it is held until it can be transferred to the intestine for digestion. The internal yolk sac is fully resorbed before birth; if the pup is released prematurely, it does not feed until this process is complete. Off Santa Barbara, birthing takes place from March to June after a gestation period of ten months, and the females mate again shortly afterward. The average litter size is six, with a range of 1–11 (rarely 13); there is no correlation between female size and number of offspring. The young are born in water deep, probably to protect them from predators. Pacific angelshark embryos grow at per month when young, slowing down to per month just before birth, and are born at a length of . Newborn pups in captivity grow at a