Having not kept long-fin variants before and being in the middle of a deep dive into Polypterus physiology has left me with the title question. While i can tell from the images that the caudal and pectoral fins seem to be extensions of the soft rays, its the internal structure of the dorsal finlets that is less obvious to me. My current assumption is that its just the soft rays in these that are extended rather than the spines. Would love to see if that corresponds to the insight and experience of those more familiar, and if so how it effects the rest of the finlets in turn.
The effects of the long fin mutation on finlet structure
- Thread starter Quack_Jaws22
- Start date
Both the soft rays and dorsal spines are extended, but to differing levels. The soft rays constitute most of the extra length, while the dorsal finlet spine extensions are slightly noticeable. If I had to say, it's about 8:2 soft ray/dorsal spine extension ratio generally. There are of course exceptions to this rule, I've noticed some long-fin varieties (predominantly albinos) have extremely malformed dorsal spines. In these individuals, the soft ray/dorsal spine ratio was more 6:4 (double the length of normal longfins). For whatever reason though, these extra long spines were always deformed in shape and were riddled with bends/knots in the structure.
Another thing to note is that a regrown long-fin finlet (when cut down to base) has even greater levels of soft ray extension than before, in addition to a less ragged appearance. The finlet spine itself regrows to the same length, but the soft rays actually get longer by 20-30%. In specimens with malformed finlets, the regrowth has significantly less knots and regrows very straight as well.
Another thing to note is that a regrown long-fin finlet (when cut down to base) has even greater levels of soft ray extension than before, in addition to a less ragged appearance. The finlet spine itself regrows to the same length, but the soft rays actually get longer by 20-30%. In specimens with malformed finlets, the regrowth has significantly less knots and regrows very straight as well.