On Friday I gave you this interesting cranium to identify:
Everyone recognised it as belonging to a fish, but the species was a bit more difficult to identify. Nonetheless jackashby, hestridgesj, Ric Morris and Cody all correctly converged on it being from an Atlantic Cod Gadus morhua Linnaeus, 1758.
Atlantic Cod – Gadus morhua by Hans-Petter Fjeld
These large fish have provided an important source of protein for the British working classes since the second half of the 19th Century and it is perhaps unsurprising that for most people the Cod is usually thought of as a crispy golden-brown creature with no head or tail, swimming in a salty sea of chips and vinegar.
Due to the abundance of Cod and the ability to catch them by trawling in local waters they were one of the few foods not rationed during World War II, along with the trusty potato, which was handy for the British populace. Not so handy for the Cod though.
The popularity of Cod as a food source has led to a considerable amount of overfishing over the years. Atlantic Cod are now classified as Vulnerable on the IUCN Redlist, with stocks fluctuating considerably in relation to trawling activity. Time to switch to alternative fish for the table perhaps?
Zygoma 
Wow, having floundered between a couple of other species guesses which proved to be red herrings, I went for a kip, er, and woke refished. I’m pleased to have got it on my fin-al guess. Thanks Paulo.
What, no puns about it looking like a victim of a-salt & battery?
Please educate a poor dumb soul (me!) – that skull looks ossified to me but I thought fish just had cartilaginous skeletons?
There are two main living groups of ‘fish’, the Chondrichthyes (Cartilaginous fish) and Osteichthyes (Bony fish). The sharks and rays are Chondrichthyes and don’t have ossified bone, all other living fish are Osteichthyes and they have varying degrees of ossification of their bones.
Don’t get me started on Lampreys and Hagfish – they’re not in the Gnathostomata so I’m not counting them as fish.
Fish taxonomy seems to be in a bit of a mess, at least according to Wikipedia. Looking at Gadus genus, the Coelacanth family, and the Osteichthyes superclass, the only agreement seems to be that they are all in phylum Chordata.
Mid level taxonomic rankings can be sketchy when you try to apply them in a cladistic classification, usually because the ranks are being applied from the historical perspective of using end-branch taxa.
‘Fish’ turn out to be a horrible paraphyletic mess when you try to apply the term to a clade, particularly when you consider that all tetrapods are Osteichthyes and indeed Sarcopterygii. Then consider that Jellyfish, Hagfish and a variety of other taxa have ‘fish’ in their name, complicating the issue of what being a fish actually entails.
I hate paraphyly.
Well, cladistics makes a mess of everything; it’s apes & monkeys all over again 😉
Hmm, I’d argue that it makes everything far simpler, with the exception of historical taxonomy 😉
Apes are monkeys and whales are fish – it all makes perfect sense when you look at the phylogeny!
Cladistics did not become well known until after I’d finished my zoology degree, so it’s not something I had to deal with at the time. My inner monkey finds it a good method, but my inner fish thinks it generates an inordinate number of clades.
I quite like the nested hierarchical approach it enables, mostly because it does away with the need for confusing and arbitrary characters (presence or absence of a tail for example). Obviously there can be issues with superabundance of clades (or more to the point a superabundance of names arising from clades), but usually these are a result of adherence to historical classificatory divisions. We like our simple high-level divisions, like fish and reptiles, but they are really a massive oversimplification of how evolution has worked over time, which can be quite misleading for the lay person.
Indeed, the proliferation of the numerous subdivisions (super-, infra-, sub-, parv-, micro-) show the limitations of the classical system.
This is getting complicated. Can’t we get back to cracking fishy puns?