Reproduction and Development

Spider conchs have separate sexes and usually pair for mating, although as many as three or four males have been associated with a spawning female (Walls 1980). Females produce between 100,000 and 500,000 eggs, which are very small and covered by a thick rounded jelly sheath. These eggs are contained in a narrow tube of jelly which forms a coiled mass coated with sand particles. When unraveled these tubes can exceed 15 m in length. However, coiled masses are rarely seen unraveled because they are held by females under the outer lip of their shell until the eggs hatch, which is usually around 5 days.

Development is spiral. The veliger larvae are free swimming and have a well developed velum or swimming fold. At first they feed on microscopic planktonic algae. As they develop they move onto larger algae and finally algal film off the water surface. This larval stage lasts around two to three weeks, after which time they will settle onto the bottom and begin to metamorphose into juveniles. Juvenile growth rate varies with food availability, but is very rapid in most cases (Walls 1980). The life span of spider conchs is not well known, but cases of specimens over 3 years of age have been recorded (Walls 1980).