Friday mystery object #359 answer

Last week I gave you this fishy mystery to have a go at solving:

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I find fish a bit tricky, simply because there are so many different species out there – 33,100 described so far and rising. That’s more than all other vertebrates combined, so it’s not surprising that they can be a challenge.

However, this cartoonish looking little fish has some quite distinctive features that help narrow down the identification. There’s the duck-face with a couple of little barbels between its eyes and the clumping of the fins to the tail end. It also has a nice colour, but as I regularly say, that’s seldom a very reliable guide.

Generally, fish shaped like this don’t swim fast, they don’t lie flat on the sea bed and they don’t wriggle through weeds. This is the shape of a clinging fish – the kind that hold fast to a surface and let the world wash over them.

There are a good fish that do this, but I did say that this one is from Ireland, which helps narrow it down even more – enough for Chris to identify it correctly. This is a Cornish Sucker Lepadogaster purpurea (Bonnaterre, 1788). These weird little fish are pretty awesome. They cling to rocks along the shore with a suction cup made from their fused pelvic fins and they can change colour to blend into the rocks they attach to. Partly this will be for camouflage to avoid predators, but it will also be to help them ambush the smaller fish and crustaceans that they feed on.

One small issue for me is that the name on the label for this specimen is Lepadogaster lepadogaster (Bonnaterre, 1788). The taxonomy of this genus was reassessed in 2002 and the northern population of Lepadogaster (including those from the UK and Ireland) was found to be distinct from the more southerly distributed population. So once again, I need to update a label because advances in taxonomy have messed up our 100+ year old information. That’s the trouble with science – it keeps finding out new stuff.

Friday mystery object #342 answer

Last week I gave you this flouncy fish to try your hand at identifying:

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It proved a tricky one, because it seems that based on genetic data it may be a species that has undergone convergent evolution with another type of fish to produce something very similar morphologically, but not actually closely related.

The similar fish would be the Sea Robins in the family Triglidae, as several of you opted for, but Wouter van Gestel and Rémi were a little more accurate in their cryptic suggestions of Flying Gurnard Dactylopterus volitans (Linnaeus, 1758).

These fish don’t really fly and only a few sources suggest that they can get any kind of glide going. Mostly they stick near the ocean bottom in shallow waters, using those oddly leg-like front fins to manage their more pedestrian movement and using the wing-like large fins to ‘fly’ underwater.

This particular specimen has lost its colour, thanks to the process of being preserved in alcohol, but when they’re alive they’re very colourful, with electric-blue spots on the fins. Perhaps more interestingly, this specimen was collected by Sir Frances Leopold McClintock, who achieved renown for his polar exploration and who was stationed in the Royal Navy’s North America and West Indies station as Commander-in-chief between 1879 and 1884. Since this specimen is from Jamaica, it seems likely that it collected in that period.

More mysteries next week!

Friday mystery object #314 answer(ish)

Last week I gave you this guest mystery object, courtesy of Joseph van Sambeek:

Mystery object. Image by Joseph van Sambeek, January 2000

The bony struts reinforcing thin plates of bone show it’s from something that lives in water all the time and which lacks lungs – you can tell this because this structure is what you get when you’re dealing with forces moving in a variety of directions, rather than mainly dealing with the constant force of gravity or compensating for buoyancy that is unavoidable when you live in water, but have lungs.

This means that many of you recognised it as being the neurocranium (that’s the bit of the skull that surrounds the brain) from a fish – more specifically from Sarah Gibson:

The first image is the skull roof, showing the elongated frontals and parietals (front of snout is left in first three images). Second image is a left lateral view, showing the internal parasphenoid that would pass between the two eye sockets. Third image is a ventral view, showing the bottom of the parasphenoid. And obviously last image is posterior view, showing the foramen magnum where the spinal cord would pass through, over the occipital condyle. It just may not look like a skull to some because it’s missing the eye sclera bones, jaws, cheek bones, pretty much anything that is not the skull roof or braincase.

However, as we all know, there are a LOT of different sorts of fish – around 33,600 described species and counting. This can make fish a nightmare to identify. However, there are some great resources out there, like Osteobase which has a very useful identification guide for various elements of a range of fish.

Alas, Osteobase didn’t have anything that fits this mystery specimen, so narrowing down to a species is rather difficult. I had the advantage of knowing that the specimen was collected in Baja California, although that was of little help in trying to get in an approximate area of the fishy family tree based on morphology, and there are still a ridiculous number of fish species is the area.

Sarah Gibson suggested that it may be a Barracuda, and it certainly fits in many aspects, but the shape of the frontals and parietals and details of the point of connection between the parasphenoid (that’s the bottom bar bit you see in the side view) don’t quite fit.

I had almost given up hope, when it occurred to me to concentrate on understanding the unusually large occipital condyle that Allen Hazen noticed, which suggested that it might be a taxon with an extremely extended rostrum (like the paddlefish or swordfish that Jennifer Macaire suggested) but with a weedier body and defined neck region since there would be no need for such a large articulation in a fusiform fish (they’re the muscular type that taper at both ends and have no neck, so don’t move their heads).

With this bizarre sounding fish in mind I was able to fairly rapidly narrow down the possibilities to one of the three species of cornetfish that live in the Pacific. I was delighted to find some great images of the skull of a Red Cornetfish, which matches the morphology very well.

Red Cornetfish Fistularia petimba from the Gulf of Mexico. Image by SEFSC Pascagoula Laboratory; Collection of Brandi Noble, NOAA/NMFS/SEFSC

Red Cornetfish Fistularia petimba from the Gulf of Mexico. Image by SEFSC Pascagoula Laboratory; Collection of Brandi Noble, NOAA/NMFS/SEFSC

However, the Red Cornetfish doesn’t really occur in the eastern Pacific, so it’s very unlikely to be that species. The Reef Cornetfish does occur in the eastern Pacific, but has only been reported in Californian coastal waters since November 2015 and this mystery specimen was collected back in January 2000 (which doesn’t make it impossible to be a Reef Cornetfish, just very unlikely). Which leaves us with the most likely identification (although by no means confirmed) of Deepwater Cornetfish Fistularia corneta Gilbert & Starks, 1904.

These long, thin fish can reach up to 2m, but they have tiny mouths that limit them to eating crustaceans, marine worms and smaller fish that they pick up from near the surface of reefs and the sea bed – presumably being harder to spot as a predator thanks to their very small frontal projected area.

I’ve asked Joe to check his specimen against the images of the cornetfish, since there’s nothing better than having a specimen in your hand when attempting an identification.

I hope you enjoyed the challenge!

Friday mystery object #282 answer

Last week I gave you this mystery object supplied by Dr David Hone:mystery282

This is the premaxilla of a fish, but that doesn’t narrow things down much, since there are 28,000 species of bony fish, leaving a huge range of possibilities.

There were several suggestions of Wolf Fish, which is what I originally thought it was myself, but that’s not what it is. Then the suggestions of various Wrasse species started cropping up – which is a lot more likely.

My first look at Wrasse teeth came when I tried to identify the fish used in the Horniman’s Merman:

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There are a lot of Wrasse, over 600 species in fact, so it can be hard to narrow down the species, especially when few comparative specimens are available.

One very helpful osteology resource for identifying fish from their bony bits is Osteobase which lets you pick a bone and start making comparisons. It’s worth keeping in mind that you need to really explore the taxonomic tree on the left of the page to get a real appreciation of how useful it is – so for example, after selecting the premaxilla, if you look at the Perciformes (the Order containing the Wrasse) you see a huge range of premaxilla specimens that help narrow down the bone you’re trying to identify.

This clearly shows that the Labridae is definitely the right family for the mystery object and the Mexican Hogfish Bodianus diplotaenia (Gill, 1862) is a very close match.

So congratulations to Richard Lawrence who I think has it right, especially since the specimen was found within the range of this species. I hope you all enjoyed the challenge!

Friday mystery object #263 answer

Last Friday I gave you this mystery object that came up at a natural materials identification course that I delivered at the Royal Albert Memorial Museum in Exeter last week:

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There were a variety of suggestions as to what it might be, but everyone (correctly) discounted the information on the label that it was a tooth.

There were some suggestions of wood and ivory, but there were two suggestions which were definitely in the right ball-park. Daniel Calleri suggested it might be something fishy, while Krista got it pretty much spot on when she suggested a dorsal barb from a skate or ray.

I’m pretty sure that it’s the spine from the leading edge of the first or second dorsal fin of a Spurdog shark in the genus Squalus Linnaeus, 1758.

Spiny Dogfish (Squalus acanthias) by Dornhai

Spiny Dogfish (Squalus acanthias) by Dornhai

These turn up every so often in collections, sometimes as decoration, sometimes as items found in Native American middens. Presumably they’re composed of keratin, which is a commonly occurring structural protein in vertebrate skin that can also form hair, horn, scales and claw.

Thanks for all your comments and well done to Krista!