The potential extinction of a not so horrid spider

550456_10151008927756171_715853807_nVanessa Amaral-Rogers is the Campaigns Officer for Buglife. After finishing her Masters in Conservation Biology at the University of Derby on bat ecology, she now works on science communications, legislation, pesticides and pollinators.






In a quarry in the South-West of England, a small spider lurks. The Horrid ground weaver (Nothophantes horridus) may not have the best name (not because it’s particularly unpleasant but because horridus means bristly in Latin) but that hasn’t stopped this tiny money spider from causing quite a stir. Very little is known about it except that for whatever reason, it only lives in two sites in Plymouth and nowhere else in the world. Now, one of the sites, Radford Quarry, is under threat from destruction.

Radford Quarry was classed of high ecological value as exhibited by its County Wildlife Site status and is the only remaining disused limestone quarry in the area that has returned to nature. Not only is the old quarry home to this incredibly rare spider, it is a haven for other bugs and wildlife. The plans to build 57 new houses here were objected to by Buglife and refused by Plymouth City Council last year but the applicant has appealed the decision.

The inquiry is due to start on the 20th January and an online petition is underway, asking for help from the public to let the planning inspectorate know how critical this site is to the spider’s survival. With only a few days left, time is running out before the petition must be submitted to the Planning Inspectorate, who will ultimately make the decision.

The Horrid Ground Weaver is quite possibly, the world’s rarest spider. There is very little existing knowledge of the ecology of the species, the spider is tricky to find due to its size and its habitat of living deep in the cracks and crevices in the limestone. However, it is thought that the species is a nocturnal hunter, hunting on the scree slopes surrounding the quarry most likely feeding on springtails and other small prey.

Listed under Section 41 of the Natural Environment and Rural Communities Act, it is acknowledged that its conservation is a national concern. However there are currently no guidelines available for how to deliver this (in common with the majority of invertebrate species added to the UKBAP priority species list in the most recent review – 2004) due to the lack of habitat and ecological data on the species.

So given that the Horrid ground weaver is only known from two sites in the world, let me recount our UK obligations to biodiversity. At the Nagoya UN Biodiversity Summit in October 2010, 192 countries and the European Union agreed to an ambitious conservation plan to protect global biodiversity. Parties agreed on a set of strategic goals and targets (the ‘Aichi’ targets) to drive action on biodiversity of which we are signed up to. One of these targets states that by 2020 the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained.

Radford Quarry meets the Defra criteria for Open Mosaic Habitat on Previously Developed Land which is listed as a habitat of conservation priority. As well as being home to the spider, there are species such as the Wall brown butterfly (Lasiommata megera) and the ground beetle Tachys bistriatus, both species have declined in numbers considerably over recent years.

The Horrid ground weaver is a perfect example of where we need to start on these targets. It is very likely that this development will push it closer to global extinction. And if the construction of 57 houses is going to have a horrific impact on this spider, what’s going to happen when we start building 300,000 homes every year?


12 Replies to “The potential extinction of a not so horrid spider”

  1. I don’t suppose that I or most of the readers of this blog will ever see this spider and even if we did it probably looks much as any other money spider. However it seems its very rare and this threatened site is one of its two homes, as far as we know in the world. Extinction is of course forever, so we should be screaming from the rooftops that this proposed development is utterly wrong and should not be allowed. Otherwise we may all regret one day in the not so distant future that we can no longer look forward to seeing this unique spider because its gone!

  2. Seems like we’re in something of a pickle …. perhaps the planning system needs reform, again!

    Maybe even we need Defra agencies to be able to protect wildlife? Having said that Hen Harriers are pretty big and obvious by comparison and they fail with that species so what chance a spider?

    We certainly need a Government that values the natural environment for the right reasons and not just as a resource to be exploited for pecuniary gain?

  3. A classic case of where the approach of assigning an economic value to wildlife would fail entirely to protect it. The horrid spider is completely obscure, provides us with no evident “ecosystem services” and its loss will affect no-one in the pocket. But economics should not over-rule everything and we must not allow this obscure little species to be sacrificed to commercial development. It will be to our lasting shame if we allow its habitat to be built over.

    1. “… provides us with no evident “ecosystem services”

      Even if it did it is difficult to envisage how the public would benefit directly as the site is privately owned and not accessible to the public – according to the Plymouth City Council website which amusingly states that a number of nationally scare (sic) species have been recorded there.

      Given that every squillionth of a hectare of soil under our feet is likely to to be home to as yet undiscovered archaea, protists, bacteria and fungi which would be of special if not huge scientific interest – should everywhere be declared a SSSI even if there is nothing scary or horrid there? This priciple could legitimately be extended to RL’s point about brownfield below. We need to have a less sizeist attitude and think beyond leg number or whether the organism has feathers.

  4. Vanessa, I can answer your question about the 300,000 houses quite simply: There is no need whatsoever for this sort of thing to happen, ever. England isn’t ‘full up’ as so many people seem to think. In fact, it is pretty much end to end neat agricultural fields, the vast majority of them, sadly, depressingly poor in biodiversity. With the sole exception of things that have to go in a particular place – roads or railways have to go in some sort of straight line, and ships can only dock at the seashore – there really is no need to develop places with high biodiversity.

    I fear, though, that you are running into a lurking problem – the institutional failure to recognise the special biodiversity value of some – actually quite a lot – of ‘brownfield’ land. In particular it can be very rich in species benefitting from disturbance and toxic soils can hold back vegetational succession to create some very special sites.

  5. A tiny spider? It’s another species at the edge of extinction. It doesn’t get bigger than that. Petition signed.

  6. As a Buglife member and someone who spends a fair bit of time working on spiders I was very happy to add my signature to the petition. Are you able to reveal who the developers are in this case Vanessa?

    1. Hi Adam

      I think it’s ok to mention the developers here, as I know some of the national papers have already named them. It’s Wainhomes which are the developers. And thank you so much for signing!

  7. I live on the waterfront at hooe lake opposite the Radford quarry have seen
    And taken pic of a tiny spider wondering if anyone could tell if
    It is the endangered spider? Thanks

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