California spiny lobster to breed, and it is thought that any adult found in Central California arrived as a larva during El Niño years. California spiny lobsters live on rocky substrates, at depths of up to . Although adults can be found in shallow water, including tide pools, they are more frequent in deeper waters. Juveniles generally inhabit rocky habitats at a depth of with dense plant cover, especially the surf grass Phyllospadix torreyi. Ecology and behavior California spiny lobsters are nocturnal, hiding in crevices during the day, with only the tips of their long antennae showing, as a means of avoiding predators. Towards dawn, the spiny lobsters form aggregations, which they maintain until dusk. At night, they emerge and feed on sea urchins, clams, mussels and worms. This activity is important in limiting sea urchin populations, and so maintaining healthy seabed communities. Natural predators of the California spiny lobster include bony fish such as the California sheephead, giant sea bass and cabezone, sharks including the horn shark and leopard shark, octopuses and sea otters. In response to an approaching predator, spiny lobsters including the California spiny lobster can produce a loud noise using the stick-slip phenomenon, akin to a bowed instrument. The bases of the antennae act as a plectrum, which is rubbed over a file on the edge of the antennular plate. If a predator is very close, spiny lobsters will flex their muscular tail in order to escape the predator, backwards. There is an annual migration, in which spiny lobsters enter shallower water in spring and summer, and head out to deeper water in fall and winter, reaching depths as great as , perhaps to avoid the effects of winter storms. Life cycle Female California spiny lobsters reach sexual maturity at a length of , which is typically at an age of 5–9 years; males are sexually mature after 3–6 years. Because all the hard parts are lost at each molt, the life span of mature spiny lobsters is uncertain; they are thought to live for 50 years or more. Spiny lobsters do not have the gonopods (first pleopods modified for reproduction) that occur in clawed lobsters and crabs, and females do not have a deep pocket on the sternum in which to store sperm. Instead, a spermatophore is transferred directly from one of the male's gonopores to the sternum of the female. The male gonopore is,