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 #365

After 10 years of posting photos from the museums I’ve worked in, I’ve finally posted enough mystery objects to have one a day for a whole year. As long as it’s not a Leap Year of course.

So here’s the 365th Friday mystery object:

Any idea what this mysterious wee beastie might be? N.B. it is a genuine enquiry, so no need to drop cryptic clues – I’m just keen to see if anyone agrees with what I’ve identified it as.

Have fun!

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!