Single Cell to Sea Urchin
Timing – will vary with species & temperature but here is a general idea:
| species | nuclei fuse and center | centro-some streak | metaphase | 1st division | 2nd division | blastula | gastrula | pluteus |
| L. pictus @18C | 20' | 50' | 80' | 90' | 2.5 hrs | 24 hrs | 2 days | 5 days |
| S. purp. @12C | 30' | 60' | 90' | 120' | 3 hrs | 24 hrs | 2 days | 5 days |
The final stage of metamorphosis from a pluteus larva to a baby sea urchin takes several months.
From fertilization to reproductive adult takes 2-5 years.