A california Sea Urchin at The Channel Islands off the Coast of California. .Sea urchins are members of the phylum Echinodermata, which also includes sea stars, sea cucumbers, brittle stars, and crinoids. Like other echinoderms they have fivefold symmetry (called pentamerism) and move by means of hundreds of tiny, transparent, adhesive "tube feet". .During the 1960s, sea urchins were considered a threat to valuable kelp (Macrocystis) resources by the.state, divers and kelp harvesters. Fishery agencies encouraged urchin fishing in the early 1970s in.southern California. From 1972 through 1985 landings ranged from approximately 3500 t to 11200 t. The.northern California fishery opened up on virgin stocks in 1985 and statewide landings peaked in 1988 at.approximately 23,600 t. Landings declined to 6409 t by 1999 with most of the decline in northern.California. Since the 1990s the fishery has remained relatively static with annual variations due primarily.to changes in urchin quality and domestic/Japanese market demand.