Giant seahorses reproduce through internal fertilization and do so four times each year (once per season). During reproduction, the female giant seahorse lays between 300 and 700 eggs in the male's incubation pouch (which resembles the pouch of a kangaroo). After 20 days, the eggs hatch, and the young remain in the pouch until they are capable of swimming on their own (about ten days). Newborn giant seahorses are about one foot long and reach maturity in eight months. About 30% of all young seahorses die before birth (either the eggs don't hatch or the young die before emerging from the pouch). Giant seahorses are monogamous and mate for life.