Laboratory Cultured Sea Urchins
Sea urchins can be raised from egg to egg in the laboratory.
With proper food, the larvae can be grown to maturity in about 3 weeks. When mature larvae are exposed to the proper chemical cues metamorphosis occurs.
Over the next 5 days the small urchins develop internal organs and then begin to feed. Sexual maturity can be reached in as little as 4.5 months.
By then the urchin is about a centimeter in diameter. Several different approaches to the study of developmental genetics are covered.
- Hybrids between the sand dollars Dendraster and Encope, in which both crosses produce offspring that have predominantly paternal characteristics;
- a preliminary description of two mutants, one which produces abnormally shaped blastula that may lead to a significant number of exogastrulae, and another that produces a large number of four- part symmetrical urchins;
- urchins produced by parthenogenetic activation and from reaggregated larval cells.
Almost all of sea urchin genetics has been limited either to studies of inter-specific and inter-generic hybrids or to the area of molecular biology.
To some extent, hybrid studies have been forced on the sea urchin embryologist because genetics at a more refined level has not been possible.
Hybrid studies have been useful and they played a particularly important part in the early investigation of the role of the nucleus vs. that of the cytoplasm.
Horstadius (1973) pre-sents an extensive discussion of these early investigations.
In many ways, research at the molecular level is just beginning, in spite of the fact that the literature is already very extensive.
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