Biometry of sea anemone and corallimorpharian cnidae: statistical distribution and suitable tools for analysis

AGUSTÍN GARESE; SABRINA CARRIZO; FABIÁN H. ACUÑA

ZOOMORPHOLOGY (BERLIN. PRINT)

SPRINGER

Lugar: Berlin; Año: 2016

0720-213X

Many studies have dealt with data on the sizes of cnidae within different groups of anthozoans, such asActiniaria, Corallimorpharia and Zoantharia. Statistical treatments of these data have been variable, according tothe evaluation of the normality; hence the use of parametric or non-parametric tests. The normality of cnidocystsize data was assumed or proved by some authors; who used parametric tests to make comparisons. Otherauthors carried out non-parametric tests, or even proposed alternative analytical methods, such as the use ofgeneralized linear models. Despite controversy about the statistical distribution of cnidae sizes, there has neverbeen an attempt to study the normality of cnidocyst size data involving a significant volume of samples, usingseveral specimens from various different species and using the same statistical approach. The objective of thispaper is to evaluate statistical adjustment to a normal distribution of cnidocyst length from four sea anemone andone corallimorpharian species. The cnidoms of all species are detailed and the hypothesis of no intra-specificvariation of cnidae sizes tested as a study case. Normality was accepted in 36.42% (sd = 17.91) of all data sets ofall cnidocyst types analyzed from all studied species, while for the rest it was rejected. The evidence suggeststhat both normal and non-normal data sets are possible, although non-normality is slightly more frequent. Intraspecificvariation of cnidocyst sizes is shown in 96.82% of the analyzed data sets. This paper provides a simpleand detailed methodology to perform comparisons of cnidae size data.