The term sail or dorsal sail has been used to refer to sail-like structures on the back of various animals. Such animals can also be referred to as sail-backed or fin-backed. Such structures include the following:
*
Neural spine sail – formed by the
neural spines
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...
of the vertebrae
*
Dorsal fin
A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...
– in some aquatic species with tall fins on their back.
*
Crest (anatomy) – a feature which has been referred to as a "sail" when occurring on the back of some animals
{{SIA