Arachnids and Aquariums
Written by Ava

Christopher Taylor is not your average Australian environmental biology student--in fact, he's currently studying spiders, scorpions, and other arachnids for school.  So why question him about his marine life pastimes? It seems Chris has a great knowledge of the distinct relation of crabs and crustaceans to arachnids, he writes a fun blog on all subjects, and at one time, he was an avid marine aquarist--partaking in a tropical freshwater aquarium and knows a thing or two about how to maintain one.  

Read to learn Chris's interesting views on all things arachnid and aquarist.

What kind of work/studying are you doing now?

I work on a group of animals called Opiliones, also called harvestmen or (particularly in North America) daddy-longlegs (a name that I have serious quibbles with - see here.) My particular family of interest, the Monoscutidae, is restricted to Australia and New Zealand. My research is mostly very traditional desk taxonomy – I look at countless specimens, and compare and contrast. I’m due to finish in a few months, and after that – who knows?

Arachnid systematics include crabs and crustaceans too, don’t they?

Well, no. Arachnids include spiders, scorpions and mites. Crustaceans (including crabs) are a distinct branch of arthropods from the arachnids – their ancestors probably parted ways more than 600 million years ago. Chelicerates (which include arachnids) differ from crustaceans in the arrangement of their legs and head – chelicerates have a pair of strong food-handling appendages called the chelicerae in front of the mouth, where crustaceans have two pairs of antennae, and chelicerates don’t have legs on their abdomens. On the other hand, the ‘horseshoe crabs’ are chelicerates (though not arachnids), not crabs at all, and if you look on the underside of one you’ll see that it has legs arranged like a spider or scorpion rather than like a crab.

Has your PhD on arachnid systematics ever branched out to include crabs, crustaceans or any kind of marine organisms? Can you work on other arachnids relate to crabs and crustaceans in any way?

While each of the major arthropod groups probably has a marine ancestry, crustaceans are the only one that has remained prominent in the marine environment. The non-arachnid chelicerates are also marine, but there aren’t that many of them. There’s four species of horseshoe crab in the North Pacific and western North Atlantic, and there’s also the pycnogonids or ‘sea spiders’.

Pycnogonids are absolutely insane animals – almost all legs and no body, so they look like a toy spider made out of pipe-cleaners. In fact, pycnogonid bodies are so reduced that some of the organ systems have moved into the legs. Because pycnogonids have such a bizarre morphology, their relationships are very uncertain (despite the common name, they’re not closely related to spiders), and not everyone agrees whether they’re even chelicerates. I think at present the arrangement is for them to be chelicerates on Mondays, Tuesdays and Thursdays, and they move elsewhere on Wednesdays and Fridays. The weekends they have off.

Arachnids are ancestrally terrestrial, but a few have moved back into the marine environment. Some spiders live in the intertidal zone, and dive into the water to catch their prey. There are marine mites, and one genus of palpigrades (minute whip-scorpion-like animals) lives as part of the meiofauna (microscopic animals living between sand grains) on sandy beaches. Some of the early fossil scorpions have been identified as aquatic (that’s scorpions proper, not sea scorpions or eurypterids which are an entirely distinct extinct group of non-arachnid chelicerates), but one of the things that’s on my wish-list is for someone to re-examine those fossils and see if the identification is supported. A marine harvestman was described from the Oligocene of Romania, but it’s almost certainly misidentified – that would be a bit like a new species of scallop being discovered living among the rock-fields on top of a mountain range.

Tell me about your blog, Catalogue of Organisms.

I started writing posts for Catalogue of Organisms nearly two years ago – and with possibly more than thirty million potential subjects, I suspect I’ll be going for a while yet. My first appearances online were more than four years ago, when Toby White invited me to write some pages for his site Palaeos  after a lengthy e-mail discussion of some pages he’d written on alveolates (ciliates and dinoflagellates). [Now I think about it, I still owe Toby some pages on graptolites (See here.) It was when I discovered Darren Naish’s brilliant site Tetrapod Zoology (, however, that I was introduced to the whole blogging platform, and realised that this was a simple means for me to inflict my own inane ramblings on the world without having to learn how to design a website from scratch (I’m not very computer-savvy overall).

I can’t really say as I have any particular plan for what I write about – it’s usually whatever happens to catch my interest at the time. I do maintain the central focus on biodiversity, systematics and such rather than often branching out into topics such as politics because I’m not so experienced in those fields and there are other writers out there doing a heck of a better job than I ever could. One tradition that I did start early on was my Taxon of the Week posts where every week I assign myself a random organism (or, more often, group of organisms) to write about, often one I myself knew nothing about previously. This has had varying degrees of success. The nadir was probably my post on the gastropod subfamily Fossarinae  which was basically an apology for my complete inability to write a post on Fossarinae, having been able to find little more out about them than the simple fact of their existence.

Why do you choose to focus specifically on organisms in this case?

That doesn’t sound so specific to me… My primary interests, and the topics that most of my posts end up revolving around, are taxonomy (the process of naming and classifying organisms) and phylogenetics (the study of evolutionary relationships between organisms). Taxonomy fascinates me, firstly, because I’ve always had a fascination for names and the relationships between names (one of my other big interests when I was younger was classical mythology, and I remember reading Hesiod’s Theogony when I was in high school), and secondly, because it is both the basis and the derivative of all other biological research. Other biologists use the products of taxonomic research to suggest their own lines of study, and then the results of their research can get used to further refine and improve the taxonomy. It’s like the ouroboros, the snake eating its own tail.

But the ouroboros is something of a double-edged analogy, because on the one hand it reflects something that feeds back into and nourishes itself, but on the other, if you’re chewing on your own tail, you run the distinct risk of disappearing up your own arse. And that, I think, is the biggest challenge facing taxonomy – on the one hand, we want a rigorous system that is able to change and improve over time, but on the other we want a system that is able to remain relevant and useful for the needs of workers in other fields.

You once wrote a guest post for us on aquarium bacteria despite not having too much experience with aquariums.  How do you know as much as you do about this kind of bacteria despite involvement with tanks?

As I believe I said in that post, I learnt the hard way. Ammonia and nitrite poisoning are not pleasant things to have happen to you, and they’re not pleasant to watch.

Interesting aside – when I was having recurring problems with water quality, I went and asked someone in the local aquarium shop what I could do about it. He asked what type of fish I had – at the time I had neon tetras (“they’re fine, they’ll handle anything” was his reply) and rummy-nose tetras (inducing a pained expression on his face and a remark that I should not have introduced such a delicate fish so early in the set-up process, and I could pretty much kiss them goodbye). As it turned out, the neon tetras all subsequently turned belly-up, while the rummy-noses thrived.

What was it like keeping a tropical (freshwater) aquarium? How long did you have it? Why did you decide not to continue the maintenance?

I had an aquarium for about a year and a half (so, you know, just long enough to get things really started), but I had to relinquish it when I moved from New Zealand to Australia (along with the mice, the canaries and the cat). Since then, I’ve not really been in a household where I could restart one (I’ve had a dog for a large part of my time here, and while I do like dogs they’re not always compatible with keeping other animals). While aquaria are low-maintenance and fairly cheap once they’re up and running, it can be a lot of work and expensive getting them started, and there’s little point getting one if you’re likely to be moving house any time soon.

What is your experience with the White Cloud Mountain minnow?

Tanichthys albonubes is an absolutely fantastic fish. It’s attractive, easy to care for and can handle almost anything that inexpert care may throw at it. It’s the pocket rocket of the fish world. Definitely something that I’d want if I was to regain an aquarium.

Would you ever consider keeping an aquarium again in the future?

I grew up in a household with lots of animals, and I’ve always tended to have a few. At the moment, I don’t have any pets (my ex took the dog) and that’s a little odd. So I think it’s pretty much a given that at some point in the future I’m going to end up with animals again (but not until after I’ve finished my thesis and hopefully settled into a career). Whether it’ll be an aquarium, I couldn’t rightly say. Maybe a terrarium will be the next project.

What did keeping an aquarium teach you?

Make sure you learn as much beforehand as you can, and try not to let your enthusiasm run away with you to begin with. Ideally, try and find someone with a ‘blue thumb’ or whatever you might call it whom you can milk for advice. Oh, and you should probably avoid putting male and female guppies in the same tank unless you really want a lifetime supply of guppies.

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