Mysids: Mysida

Mysids spend much of their time swimming. They can swim up, down, forward, and backward with equal agility. When threatened they quickly jerk backward by flexing the abdomen and fanlike tail forward against the thorax. Females have very small pleopods and use their pereopods for swimming. Burrowing species rise up into the water at night to feed and sink down to the safety of the bottom during the day to avoid predators. Some species form swarms that may reach several miles in length and three or more feet in diameter.

Both males and females are required for reproduction. Females produce chemicals, or pheromones (FEH-re-moans), to attract males. Males and females sometimes align their bodies, belly-to-belly and head-to-tail, to mate. The male's sperm is either injected or washed into the female's marsupium. Within 30 minutes eggs are released into the marsupium and fertilized.

After hatching the young remain and develop in the marsupium for several weeks or months, depending on species and water temperature. The young eventually leave the marsupium with a full set of appendages and reach adulthood in about a month at water temperatures of 68°F (20°C).