The longfin sawpalate is differentiated from the stout sawpalate by one characteristic
– the absence of a projection of the first branchiostegal ray (a structural
part of the underside of the gills) beyond the gill opening. The stout sawpalate
possesses this feature, but otherwise the two species appear identical. It is
now considered questionable whether the longfin is a separate species since stout
sawpalates have been found that possess the gill projection on one side, but not
on the other. Perhaps this morphological feature is highly variable within the
species, with some individuals having it on both sides, some on one, and others
on neither.
Longfin sawpalates are long, eel-like fishes
that grow to a maximum length of 80 cm. They have delicate anal and dorsal fins
that start a head length behind the gill opening and run the length of the body.
Their pectoral and pelvic fins are much reduced. The characteristic blade or saw-like
teeth run in two parallel rows on the roof of the mouth, which is long and narrow.
Its overall body colour is iridescent brown to black, but the skin is often lost
from specimens that are hauled up from great depths.
The longfin sawpalate is found in the Canadian Arctic in Davis Strait off the
coast of Baffin Island, but elsewhere is widespread through the Atlantic, Pacific,
and Indian oceans. It frequents depths from 150–4500 m, but nothing else
is known about their biology.
