Development and malformations of the vertebra in the early stages of starry flounder Platichthys stellatus.

The purpose of this study was to analyse the normal vertebral development and the status of malformations for Platichthys stellatus fed in artificial conditions. Eggs were taken from cultured parental P. stellatus, being incubated until larvae, juvenile in an artificial recirculating system. Specimens that were randomly collected from hatching to 75‐day‐old were dyed with alcian blue and alizarin red. Vertebral development as cartilage was initiated at 6‐day‐old by the emergence of the anterior haemal arches and spines in the haemal region, followed by the neural arches and spines. The vertebral centra were visible at 10‐day‐old. The initial ossification events happened on the exterior border surrounding the vertebral centra where the haemal and neural arches connected to the vertebral centra in the front of the haemal region at 14‐day‐old. The parapophysis firstly formed in the most posterior prehaemal region at 16‐day‐old. All parts of vertebral column were ossified at 30‐day‐old, except for the haemal and neural spines from preural vertebrae until the end of the experiment. The total vertebral numbers were no significant differences from Stage 3 to Stage 5. The observed skeletal malformations were classified into 22 types. Among all specimens analysed, 62.9% of the ones presented malformation in the skeleton. From these, 27.3% of the specimens showed only one malformation, and 35.5% revealed multiple malformations. The frequencies of malformations were increasing from Stage 2 to Stage 5 with the highest value of 66%. [ABSTRACT FROM AUTHOR]