Urbanization is supersizing spiders | Hacker News Reader

Urbanization is supersizing spiders

blogs.smithsonianmag.com

59 pointsbifrost33 comments

Spider size is a surprisingly interesting topic, with quite quick evolutionary changes in both directions, and lots of interactions between spider size, web size, prey size, etc.

Here's an excerpt from a book about some effects that influence the size of orb-weaver spiders (internal citations omitted):

Spider size has evolved rapidly and diversely throughout the evolutionary history of spiders, both in terms of absolute size and relative sexual size dimorphism. In general, there seems to be a trend towards increased spider body size, especially for females, across the phylogenetic tree. ... For orb web spiders, the most common explanation is likely fecundity-based female gigantism because clutch size, the most commonly used proxy for spider fecundity, generally strongly correlates with female body size both intra- and inter-specifically. ...

[M]ight the function of orb webs also play a role in spider size evolution? We believe the answer is yes. In general, orb web architecture determines the type of prey intercepted and retained that could be consumed by the spider. Thus, spider size evolution may occur under selection for how webs might fill 'empty niches'. For example, tiny anapid and mysmenids build orb webs that capture insects ignored by larger orb-weavers, and theridiosomatids specialize on mosquitoes that are too small to be relevant to the diets of large spiders but also such specialized fliers that they are rarely captured by the webs of other, less-specialized spiders. ... Similarly, the largest orb-weavers make webs powerful enough to retain the largest insects, which are simply not available to smaller spiders, and their webs can sometimes even subdue vertebrate prey. Orb webs may place an upper limit on the maximum size achievable by orb web spiders due to increases in the costs of producing webs in larger spiders and due to differences in how the kinetic energy of insect prey versus the stopping powers of orb webs scale with size.

Source: http://www.amazon.com/gp/product/0124159192/ref=as_li_ss_tl?..., pp. 225-226

Non-Australians who click on linked article on huntsmans[1] should note these are regular visitors in our homes. But as much as I love scaring foreigners with our wild life (google dropbear) the ones you see day to day in urban environments are generally 10cm across and happily cohabit with humans.

[1] http://largestfastestsmartest.co.uk/largest-spiders-in-austr...

Its a shame Hollywood has vilified certain animals and insects like sharks, snakes, spiders and bats. Now we are unreasonably fearful of them.

I doubt that. Hollywood probably used them as villains because people were already scared of them. The fear of spiders, ... is believed to be a primal fear, an evolutionary safeguard, because some of them are indeed dangerous (and especially there were mankind is believed to have started).

Don't know how much of that is proven. And I wasn't aware of a typical fear of bats (maybe I watched to much batman).

A review with references to the ease of fear learning in primates.

http://www.psychologicalscience.org/journals/cd/12_1/ohman.c...

> The fear of spiders, ... is believed to be a primal fear, an evolutionary safeguard

[Citation Needed]

I've heard that too, but all the evidence I've seen indicates arachnophobia is a largely cultural European phenomenon.

For example, see this: http://animalsplatform.org/assets/library/274_s214.pdf

Also note that in parts of Asia and South America people actually eat spiders.

http://www.sciencedirect.com/science/article/pii/S0005796798...

You can't just link to a paper (behind a pay-wall, of all things) and expect me to find the relevant part! Explain why it's relevant. I just spent 20 minutes reading that paper ಠ_ಠ and I see no evidence to support the argument. The paper I linked to by the same author explicitly contradicts it:

>The tendency of Europeans and their descendants to be fearful of spiders does not seem to be shared by people in many non-European cultures, and this is not consistent with those evolutionary accounts of spider fear which suggest that spider fear should be a common feature of the human gene pool regardless of culture (e.g. Seligman, 1971). However, it is consistent with the present thesis which argues that spider fear developed as a result of the association between spiders and disease in Europe after the tenth century

Say [Detailed Sourced Explanation Needed] rather than [Citation Needed], then.

It's not a real citation if it doesn't support the point.

Linking to a paper and hoping people believe it supports you because it's a paper is poor form. I expect people to be able to analyze their citations - that's pretty standard practice.

http://arno.unimaas.nl/show.cgi?fid=2382

I googled for the paper title and this was the second result. It's just a scan, but it's readable.

Yeah the huntsmans are very welcome in my home, they can eat all the cockroaches and mozzies they like! Geckos too, because they're cute :)

My main concern is my extreme paranoia for having 'something like that' walk on me/in the bed while sleeping, Uhh...Brrr!

Having lived in black widow country as a youth, I have the same freak-out-at-crawly-while-sleeping syndrome.

side note: do not watch the video in the article if spiders freak you out

Scary as hell when you're taking a shower and happen to look up and oh, hey, look, there's a fully grown grey huntsman up there!

OK just don't you move, I'll finish up my shower and get out of here ASAP...

How do you people survive to adulthood?

As a non-Australian, big spiders don't bother me. Cockroaches on the other hand...

Well, I was thinking more of, say, the estaurine crocodile, white shark, box jellyfish, taipan, funnel-web spider, red back spider, blue-ringed octopus, stone fish, brown snake, banded sea krait, &c. &c. &c.

I have to say, I'd rather have a 20-foot crocodile in my back yard, than a 1-foot spider.

Me too.

Yep. At least you can see the crocodile and can stay away from it. Roaches though? Those fuckers scurry all over the place and you don't see them until they start crawling on you...

Then again, no cockroach has ever jumped out of the water and pulled someone under, to drown and then get all soft and rotted and delicious.

As David from 27b/6 is wont to say: (In Australia) "... practically every living creature can kill you in under three minutes. Our primary spoken language is screaming".

Wow! That is very interesting.

In the US there are pretty comprehensive "pest-control" measures taken in urban apartment complexes to ensure that there are absolutely no insects, spiders or geckos indoors. I probably see a really tiny "house spider" (which is probably a centimeter across in size) once or twice a year inside my apartment.

So my question is it common to not have pest control in OZ or is your house the exception (since you are nature lover maybe)?

As a scaredy-cat brit, when I moved to Australia the first thing I did was spray the outside of my house with spider repellent :)

Why not? Well for the huntsmen will eat the smaller and harder to control insects (like cockroaches, of which there are plenty). Think of them as natural pest control.

We used to have one in our apartment, which we named Fred. RIP Fred!

I've never bothered, neither did my parents. Currently we have three baby geckos hanging out with their parents out the front of the house, a couple of hunstmans, and moths floating around from time to time.

I think nature is awesome :)

/from brisbane

The thing about geckos and (as much as it pains me to admit it) spiders is that they prey on much more noxious and difficult to control vermin, particularly the mosquito. This is pretty useful when spiders are basically harmless and Anopheles the most dangerous animal in the world.

In the tropics we had some pest control for cockroaches but down south we don't really bother.

Australia: even the mammals are venomous[1].

[1] http://en.wikipedia.org/wiki/Platypus_venom

A few years back, urbanization was also causing the breasts of Australian women to grow larger :-|

http://www.news.com.au/entertainment/fashion/dd-cup-runneth-...

Small environments also have an influence over the body size of animals. Surprisingly the change does not always occur in the same direction: see Insular Dwarfism and Insular Gigantism.

[1] http://webecoist.momtastic.com/2010/08/09/insular-dwarfism-1...

[2] http://webecoist.momtastic.com/2010/08/02/animal-gigantism-1...

Speaking as a severe arachnophobe and a committed city dweller: great. Just great.

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