Friday mystery object #41 answer


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 dHistoire Naturelle which shows how the spines are positioned.

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

4 thoughts on “Friday mystery object #41 answer

  1. Nah, don’t make it easier, that was a good ‘un! At least all its characteristics were clear and it looked very weird. Sorry I didn’t have a guess, but I got the the point of seeing, as you say, the articulation and realised I had no idea whatsoever beyond that!

    • Thanks – glad you enjoyed the challenge! When I first found it in a drawer I had no idea what it was either, so I thought it might pose a bit of a tricky one. I’m at a conference this Friday, so I may be limited in what I can offer up as this week’s object – unless I can persuade the guys at Plymouth to let me post up one of their specimens…

    • Brilliant – very clearly a sloth and by the looks of it, it was dead before the kids even found it. Childish imaginations running wild I’d wager…

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