Final answer:
The development of sea urchin eggs without sperm, which is induced by hypertonic seawater or other stimuli, is referred to as parthenogenesis. It's an asexual reproduction method resulting in haploid or diploid offspring depending on the species.
Step-by-step explanation:
When sea urchin eggs are treated with hypertonic seawater or subjected to other stimuli, causing them to develop without the presence of sperm, the phenomenon is called parthenogenesis. Parthenogenesis is a form of asexual reproduction where an egg develops into a complete individual without being fertilized, and the resulting offspring can be either haploid or diploid, depending on the process and the species.
This occurs in various invertebrates and is a natural form of reproduction that allows for the development of new individuals without the need for sexual fertilization. Sea urchins are ideal model organisms for studying this process due to the ease of obtaining gametes, the lack of need for sterility, and the transparency of eggs and embryos for observation.
The consistency of development timing in embryos is also advantageous for biochemical and molecular studies in early development.