Twait shad destruction. Conservation of this species is covered by Appendix III of the Bern Convention and Appendix II and V of the European Community Habitats Directive. The twait shad is a typical herring-type fish and much resembles the allis shad. It has no lateral line and the belly is more rounded than that of the sprat and Baltic herring. The gill cover is ridged and the caudal peduncle has large, plate-like scales. This fish is more colourful than the Baltic herring. The back is a bluish green colour and the head brownish with a golden tinge on the operculum. The flanks
Caudal cell mass dysraphisms. These types of abnormalities arise from specific structures formed in the caudal mass, for example if proper differentiation of the caudal mass doesn't occur, it could result in a type of spinal dysraphism. One example of spinal dysraphism is caudal regression syndrome. Patients suffering from caudal regression syndrome can experience a varying degree of the abnormality ranging from partial lack of the tail bone and pelvis to more significant cases where there may be paralysis and, as a result, inhibited function in the bowel and bladder. This abnormality can be caused by the caudal cell mass not developing properly