Fin Spine
Definition
A stiff calcified spine present anterior to the dorsal fins in many shark species (notably spiny dogfish, Squalus acanthias). Spine presence, shape, and histological banding pattern are species-diagnostic characters.
- Location
- Anterior to the dorsal fins
- Example species
- Spiny dogfish, Squalus acanthias
- Diagnostic features
- Presence, shape, histological banding
Common questions
Why is histological banding in a fin spine useful for species identification?+
The banding pattern reflects growth increments that differ in structure and frequency between species, so a cross-section examined microscopically can help assign a spine to a species even when only a fragment is recovered.
What does the presence or absence of a fin spine indicate about a shark specimen?+
Fin spines occur only in certain shark groups such as dogfish, so their presence on a recovered fragment narrows the range of candidate species before any finer histological comparison is done.
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