1. Sexual Maturity: Krills reach sexual maturity at different times depending on their species and environmental factors. When they are ready to breed, they undergo a process called "gonadal development," where their reproductive organs mature.
2. Spawning: During the breeding season, krills engage in synchronized mass spawning events. This occurs in specific areas where environmental conditions are favorable, such as the presence of food and suitable water temperatures.
3. Male-Female Pairs: Krills are heterosexual, meaning there are distinct males and females. During mass spawning, male and female krills form temporary pairs for reproduction. The males deposit their sperm, while the females release their eggs into the water.
4. Fertilization and Embryo Development: After being released, the sperm fertilizes the eggs, leading to the formation of zygotes. These fertilized eggs develop into embryos, undergoing various stages of cell division and growth within the water column.
5. Nauplii Larvae: The embryos eventually hatch into tiny larvae called nauplii. These nauplii are free-swimming and have a unique morphology, distinct from adult krills. They feed and grow in the water column, undergoing several molts as they mature.
6. Furcilia Larvae: After multiple molts, the nauplii develop into furcilia larvae. Furcilia larvae have a more elongated body and appendages compared to nauplii. They continue to feed and grow in the water column, molting several times during this stage.
7. Juveniles and Adults: As furcilia larvae mature and go through additional molts, they eventually transform into juvenile krills. Juveniles resemble adult krills but are smaller in size and may have slight variations in their morphology. Over time, juveniles grow larger, develop fully formed adult features, and join the adult krill population.
It's worth noting that the exact timing and duration of the breeding process, as well as the specific stages of development, may vary slightly among different krill species. Additionally, environmental factors such as temperature, food availability, and predators play crucial roles in krill reproduction and survival.