Table of Stages

Developmental timetables for Sea Urchin and Sand Dollar embryos at various temperatures
Strongylocentrotus droebachiensis Strongylocentrotus purpuratus Echinarachnius parma Arbacia punctulata
Stage 4 C 8 C 10 C 15 C 20 C 23 C
Fertilization 0 0 0 0 0 0
2-Cell stage 5 hrs 3 hrs 3.5 hrs 1.5 hrs 1 hr 50 min
4-Cell stage 8 hrs 5 hrs 5 hrs 3 hrs 1.8 hrs 78 min
8-Cell stage 10.5 hrs 6.5 hrs 6.5 hrs 4 hrs 2.4 hrs 1.71 hrs
16-Cell stage 14 hrs 8.5 hrs 8.5 hrs 5.5 hrs 2.25 hrs
32-Cell stage 18 hrs 11 hrs 2.78 hrs
Morula 6.5 hrs 4 hrs
Early blastula 7 hrs 6 hrs 4.5 hrs
Mid-blastula 8 hrs 6 hrs
Hatching blastula 50 hrs 30 hrs 27-28 hrs 12 hrs 10 hrs 7-8 hrs
Early gastrula 25 hrs 12-15 hrs
Mid-gastrula 50 hrs
Late gastrula 57 hrs 31 hrs 17 hrs
Prism stage 6.5 days 4 days 80 hrs 48 hrs 18 hrs
Early pluteus 11 days 7 days 4.7 days 50 hrs 48 hrs 20 hrs
Late pluteus 72 hrs 24 hrs
Metamorphosis 7-22 wks 63-86 days 5-16 wks