On Friday I gave you this formidable looking object to identify:

Many  suggestions related to the saw-like appearance of this object, proposing either a human-made saw or the rostrum (nose) of a saw-fish (which are endangered cartilaginous fish of the genus Pristis). The closest answers all made reference to the articulation at the end of this object, which is the significant clue as to what this object is – the “teeth” are just secondary details.

Jake was the first to come close, followed by Kevin the epic and KateV, who gave a sensible mechanical breakdown of the likely use of this element. I’m not all that surprised to say that this week no-one worked out that the mystery object is a pectoral spine from the granulated catfish, Pterodoras granulosus (Valenciennes, 1821).

These South American catfish are about 65-70cm long and weigh up to 6.5kg. They are nocturnal predators and they are sometimes called “talking catfish” by aquarists because of the low frequency grumbling noises they make at night. They have a series of scutes along their sides and these spines as the first ray of their fins. To the best of my knowledge the toothed sections are used as stridulations for generating sound (hence the grumbling noise they make at night), although I strongly suspect that they perform a defensive role as well. There are a variety of photos of the beastie in question here – including a rather nice x-ray by the Museum National d‘Histoire Naturelle which shows how the spines are positioned.

Maybe I’ll try something a bit less tricky this Friday…