Statistical relationships of cnidocyst sizes in the sea anemone Oulactis muscosa (Actiniaria: Actiniidae)

Abstract

This study analysis the multivariate statistical relationships among cnidocyst types and tissues in terms of cnidocyst capsule size in the sea anemone O. muscosa. In a total of 12 individuals we measured the length of 30 unfired capsules of each cnida type, taken randomly from each of the following tissues: tentacles, acrorhagi, column, actinopharynx and mesenterial fila-ments. In these tissues, we found spirocysts, basitrichs, microbasic b-mastigophores, microbasic p-mastigophores and holotrichs. Thus, a total of 5400 measurements were made. Looking for a common pattern of variation, a principal components analysis (PCA) was performed on the data matrix, among cnidocyst types for each tissue and between tissues for each cnidocyst type. The results showed that the lengths of most cnidocysts, whether from the same or different tissues, are not statistically related to each other, suggesting that different forces (cnidogenesis, replacement dynamics, etc.), could affect in various forms the development and therefore the length of each cnida, depending on the type or tissue of origin.