Friday mystery object #373 answer

Last week I gave you this pretty cool skull to have a go at identifying:

 

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As everyone recognised, it’s the skull of a snake. I think that’s clear from those extremely long quadrate bones (highlighted in purple in the top view), with which the lower jaw articulates to allow a huge gape for swallowing prey whole. However, there are a lot of snakes out there – around 3,600 species, which means there are lots of possibilities for the species that this particular skull belongs to.

The side view allows us to rule out quite a few possibilities, since it’s clear from the teeth that this isn’t one of the front-fanged snakes (vipers and elapids).

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Rattlesnake skull, with its big front fangs.

The light construction of the skull suggests it’s not one of the constricting snakes, which have much more robust skulls for dealing with the forces generated by the struggles of relatively large prey.

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Python skull, with a robust construction for wrangling prey.

The teeth are quite small and although there are a couple of slightly longer ones in the tooth row, they hardly count as real fangs at a paltry 3mm long. So we’re probably dealing with one of the ‘non-venomous’ colubrid snakes (many of these are actually venomous, but lack the appropriate tools to deliver that venom through human skin).

Of course, there are still well over a thousand possible species in the Colubridae – but this is where you have to start ruling out possibilities by comparing the specimen against species that are common and widespread, to begin the process of narrowing down the options.

Since this specimen is in the Museum in Ireland, Europe is a good place to start looking for likely candidates (Ireland itself being famously devoid of native snakes). There is a rather old (published in 1913), but still very useful reference called The Snakes of Europe, by G. A. Boulenger which has a section on identifying species based on their skulls.

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Fig. 6Skull of Tropidonotus natrix. (From British Museum Catalogue of Snakes). Illustration from The Snakes of Europe, by G. A. Boulenger, 1913

If you take a look through, it quickly becomes apparent that there is one species that matches the mystery object very closely – even to the position of the slightly larger teeth. It’s a species that has an interesting defense mechanism that jennifermacaire referred to:

…The closest skull I could find is from a snake that likes to roll over and play dead…

This is a fascinating behaviour seen in several snake species, but Jennifer is correct that it is seen in the species that this skull is from – the European Grass snake Natrix sp.

Of course, the story then gets more complicated again, since a couple of subspecies of Grass snake have been elevated to species in the last few years. The Iberian subspecies Natrix natrix astreptophora was recognised as N. astreptophora in 2016 and the subspecies N. n. helvetica found west of the Rhine (including in the UK) was updated to N. helvetica in 2017.

These studies were based on genetics and I’ve yet to see any way of differentiating between these species using skeletal features, so for now the best I can say about this specimen is that it’s Natrix sp. I hope you enjoyed that little slither into the world of snakes, which seems to have opened a bit of a can of worms…

 

 

Friday mystery object #372 answer

First of all, I’d like to wish you a very happy and healthy 2020!

Last year I gave you this festive-looking beetle to try your hand at identifying:

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It was a bit of a tricky one to get to species, since beetles are notorious for their huge diversity, plus they can vary in appearance quite significantly within a species.

James Bryant recognised this as a member of the Buprestidae, which is a family of wood-boring beetles that are commonly known as Jewel Beetles due to their metallic and iridescent colours. In fact, the wing cases (or elytra)  of some of the most colourful of these beetles have been used in traditional beetlewing jewellery in the parts of Asia where they are found.

Going beyond the family, the identification katedmonson provided through a great cryptic clue was spot-on (assuming I understood it properly). This particular specimen is an example of Chrysochroa rajah Gory, 1840, but in the collection it is still labelled under the synonym C. chinensis.

This species is one of those with a wide distribution, several subspecies and a variety of different colours and patterns, which can make it hard to identify based on just an image of the overall body (or habitus as it’s referred to by entomologists). Just to give you an idea of what I mean, here’s an example of the same species in the National Museum, Prague:

Chrysochroa rajah from southern China. Photo by Hectonichus 2010

Blue and green form of Chrysochroa rajah from southern China. Photo by Hectonichus 2010

So well done to katedmonson for getting this tricky identification. Look out for another mystery next week!

Friday mystery object #369 answer

Last week I gave you this weird, but rather nice object to have a go at identifying:

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Most people seemed to recognise it as the tympanic region (that’s the bony ear-related region) of a whale. But of course, I’m demanding when it comes to getting an identification and there are plenty of species of whale to rule out.

The size immediately narrowed down the possibilities – this is pretty small for a whale. But what really gives it away for the small number of people intimate with the cranial anatomy of whales (which goes beyond even my bone-nerdery), is the spongy bone attached to the tympanic bulla (that’s the bulb-shaped bit of bone that houses the inner ear).

This feature is proposed as a possible pressure receptor that’s found in the Pygmy Sperm Whale Kogia breviceps Blainville, 1838. Amazingly, Conor Ryan identified this on Twitter – his handle of @whale_nerd explains everything you need to know.

Kogia breviceps by George Brown Goode, 1887

Kogia breviceps by George Brown Goode, 1887

These toothed whales only grow to around 3.5m, which is pretty small for a whale. They share some features with their much larger Sperm Whale cousins, particularly in relation to adaptations for echolocation.

I was fortunate enough to meet Conor Ryan at the weekend at the Irish Whale and Dolphin Group conference. There were plenty of whale enthusiasts around and it was fantastic to get a chance to learn more about this incredible group of animals from a lovely bunch of passionate people.

While I was there, I also picked up some useful tips on differentiating between species of dolphin, so I may have to share those with you soon…

Friday mystery object #367 answer

Last week I gave you this rather exciting new specimen from County Kerry, Ireland to have a go at identifying:

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Perhaps unsurprisingly, it was recognised by pretty much everyone. For people based in the Americas it’s not that unusual a species and for people on the other side of the Atlantic, especially those with an interest in birds, there has been a bit of a stir in the press about this specimen.

This bird is clearly a member of the heron family – the Ardeidae – with its distinctive spear-shaped bill, relatively long legs and long and somewhat kinked neck. But it’s tiny. In fact, this is one of the smallest members of the Ardeidae, perhaps a bit longer in the body than a Dwarf Bittern, but just a bit lighter and quite different in plumage.

Dwarf Bittern in South Africa. Image by Mark Tittley, 2011

Dwarf Bittern in South Africa. Image by Mark Tittley, 2011

And this particular specimen is very light indeed. Sadly it was probably undertaking a migration south from its North American breeding grounds, when it got caught up in hurricane Lorenzo, which blew it off course, forcing it across the Atlantic Ocean, where it finally made landfall in Farranfore in County Kerry, on the west coast of Ireland on 7th October this year.

Exhausted, emaciated and severely dehydrated, the poor bird lasted less than an hour in Ireland, despite efforts to keep it going by John O’Donoghue, the owner of the garden it ended up in. John and his neighbour Anthony O’Connor recognised that it wasn’t a bird normally found in Ireland, so they got in touch with BirdWatch Ireland to find out what it was and let people know about their unfortunate visitor.

Brian Burke and colleagues from BirdWatch Ireland identified the specimen as being a Least Bittern Ixobrychus exilis (Gmelin, 1789) and they got in touch with me at the Dead Zoo about getting the specimen added to the collections, since it’s a first record of this species occurring in Ireland – and only the 10th known to have made it across the Atlantic.

Of course, I was delighted to accept on behalf of the Museum and John arranged to get the bird to me in Dublin via his local Teachta Dála (the Irish equivalent of a Member of Parliament). Now the bird is safely stowed in the Museum’s freezer awaiting assessment by a taxidermist, to see whether it’s in good enough condition to be mounted, or if I’ll need to find another way of preserving the specimen as part of the permanent collection.

If not as taxidermy, this might be as a study skin, a fluid preserved specimen or even a skeleton – each offers different information for future use. But however it gets preserved, it will provide an important physical record of an unusual visitor to the Nation for future scientists and members of the public. After all, that’s a huge part of what collections are for.

Friday mystery object #365 answer

Last week I gave you this little critter to have a go at identifying:

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This particular shrimpy specimen arrived as an enquiry, after it was found in some Irish drinking water.

Prawn cocktails may be a thing, but most of us don’t think of shrimps (or shrimp-like decapod crustaceans) as an ideal addition to a beverage.

According to WHO these critters aren’t actually a health problem if they get into the water supply in temperate regions, where they don’t carry significant parasites or pathogens – but it’s a different story in the tropics.

Knowing which species this is could help in working out how it might have entered the water supply. I’m not an expert on crustaceans by any means, but there are useful keys out there [links to pdf] for working out this kind of information and I’m very fortunate in having to hand the expertise of my predecessor at the Dead Zoo, Mark Holmes, who specialises in crustaceans and is still often at the Museum doing research. Of course, I also have all of you lovely people!

My first thought on seeing this was that it was one of the Gammeridae, based mainly on my exposure to many photos of Gammarus shrimps infected by microsporidian parasites that change them from males into females (which is some fascinating biology). I was therefore delighted when so many of you put forth suggestions in that same area.

By working through the key of Irish shrimp I narrowed it down to Gammarus pulex (Linnaeus, 1758), which was also suggested on Twitter by @RobertsZivtins and @DianeBarlee. It could be G. tigrinus or perhaps G. lacustris – or of course a species not previously recorded from Ireland that doesn’t appear on the key.

However, I got it fresh and there were no stripes and the uropods and telson (taily-bit) looks more pulexy to my eye.

I am now eagerly waiting to hear what Mark thinks – I will update this post as soon as I do!

I have now checked with Mark and he identified this as G. lacustris so it looks like the taily bit isn’t pulexy after all. Thanks Mark!

Friday mystery object #364 answer

Last week I gave you this fantastic skull from the Dead Zoo to have a go at identifying:

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It’s clearly a bird and it has a distinctive shield of keratin at the base of the bill that helps with the identification. There aren’t many birds with shields like this, although there are plenty with casques, wattles, combs and crests that need to be ruled out when thinking about possibilities.

The group that springs to my mind when it comes to facial shields like this are the Jacanas or Jesus birds, named for their apparent ability to walk on water which Wouter alluded to in the comments. Of course, they don’t actually support themselves on the surface of the water (unlike the Common Basilisk), rather they walk on vegetation at the water surface, spreading their weight across ridiculously long toes.

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Lesser Jacana, by Derek Keats, 2016

Not all Jacanas have facial shields, but there are a few that do, including the Northern Jacana Jacana spinosa (Linnaeus, 1758) that lives in South America – which is the species that this mystery skull belongs to.

The Wattled Jacana can be ruled out because it has additional drooping lobes on the lower part of the shield. There is also a Crested Jacana that looks similar to this, but the shield runs along the skull more, rather than across the front of it.

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Northern Jacana, by Benjamin Keen, 2012

The Northern Jacana also has yellow spurs on its wings that it uses for defence, which is quite distinctive. Here’s the skull back on its skeleton – you might just be able to make out those bony spurs on the wing.

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You may notice that the scientific name on this specimen label is very different to the scientific name I used – yet another example of some old taxonomy that will need updating in the collection. Some jobs are unending in museums!

Friday mystery object #363 answer

Last week I gave you this crusty critter to identify:

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It’s not the easiest mystery object, since there are around 850 species of crab, and several converge on similar forms. However, the triangular body and spindly legs meant that everyone recognised this as a species of spider crab in the Superfamily Majoidea.

Beyond that it gets harder, although there are resources out there to help. The Marine Species Identification Portal has a useful key for species that occur in the North Sea. I know that’s not always useful in these instances, but as it turns out, this particular species has a range across the East Atlantic and into the Mediterranean, including populations in the North Sea.

This little crab is Pisa armata (Latreille, 1803), which is one of several spider crabs that camouflage themselves with sessile animals and algae from their local environment, earning them the name Decorator Crabs.

Decorator crab covered in stinging hydroid polyps, which defend the crab while benefiting from food scraps and greater mobility. Image by Nick Hobgood, 2006

Decorator crab covered in stinging hydroid polyps, which defend the crab while benefiting from food scraps and greater mobility. Image by Nick Hobgood, 2006

Bit of an obscure one for you, but Diane Barlee did figure it out on Twitter, so it was manageable. Watch out for more mysteries next week!