Preliminary study on chemical cues in the conspecific aggregation of Styela canopus

The effects of conspecific adult tunic extracts and larval tissue extracts in different concentrations and the effects of different larval density on settlement and metamorphosis in the Styela canopus larvae were investigated.Experiments show that conspecific adult tunic extracts and larval tissue extracts both were able to induce Styela canopus larvae to settle and metamorphose in the concentrations of 5% and 10%.It is found that Styela canopus larvae are induced to settle and metamorphose at densities of more than 25 larvae per millilitre and the settlement and metamorphosis are not influenced at densities of lower than 10 larvae per millilitre.All results suggest that the ability of chemical factors in adult tunic extracts or larval tissue extracts to induce settlement and metamorphosis may explain the conspecific aggregation of Styela canopus in nature.