1 2 3 4 5 6

		Results: Temperature had an effect on the cleavage rates of developing sea urchin embryos. Generally, the higher the environmental temperature, the faster the embryo divided. At 37°C, the sea urchin eggs reached the first cell cleavage at 40 minutes after fertilization, and cleaved the second time at 65 minutes after fertilization. Abnormalities in the gastrulating embryo were observed at 37°C. Under ideal conditions, 22°C, the embryos first cleavage cycle occurred at 60 minutes after fertilization and the second cleavage cycle at 100 minutes. At 14 °C, the cleavage rate was dramatically slower, with the first division taking place at 95 minutes after fertilization. Only 50% of the embryos continued to divide, in which they reached the second cleavage at 205 minutes after fertilization. When the cultures were photographed 95 minutes after fertilization, the embryos incubated at 14°C had only divided once, the control embryos had divided twice, and the embryos incubated at 37-38°C had already divided 3 times (Figure 2). Figure 2. Sea Urchin embryos 95 minutes after fertilization. Embryos (A.) incubated at 14°C, (B.) incubated at 22°C(Control), and (C.) incubated at 38°C. Twenty-four hours after fertilization (Day 2), the control group had developed normally. The majority of the embryos displayed archenteron formation and were motile. Not all embryos kept at 14°C had hatched by day 2. The ones that had hatched did not have archenterons and were not motile. The majority of the embryos kept at 37°C had died and lacked archenterons. The remaining embryos had developed abnormally, had not hatched and were smaller than the control group (Figure 3) Figure 3. Sea Urchin embryos 24 hours after fertilization. Embryos (A.) incubated at 14°C, (B.) incubated at 22°C(Control), and (C.) incubated at 38°C. Forty-eight hours after fertilization, all embryos of the control group were at the pluteus larvae stage. At 14°C, the vast majority of the embryos were dead and those alive still did not show signs of regular development such as archenteron formation. At 37°C, there were some pluteus larvae but the majority of the embryos were small and unhatched (Figure 4). Figure 4. Sea Urchin embryos 48 hours after fertilization. Embryos (A.) incubated at 14°C, (B.) incubated at 22°C(Control), and (C.) incubated at 38°C.