Spiders and Harvestmen

Contact details of YNU Recorders:

Spiders and Harvestmen

Spiders and harvestmen belong to the group (class) of invertebrates, collectively known as the Arachnida, which comprises eleven orders, of which there are four native to the UK and Yorkshire. These are the mites and ticks (Acari), false-scorpions (Pseudoscorpiones), spiders (Araneae) and harvestmen (Opiliones).

The recorders have a particular interest in, and are capable of identifying spiders and harvestmen. The former can be distinguished from harvestmen in having two obvious body segments: the cephalothorax (‘head’) and abdomen, whilst harvestmen have a single body part. Furthermore, harvestmen have two eyes, normally raised on an ocularium (‘turret’) which can be furnished with spines. Spiders, either have six, or more normally, eight eyes. Both of course, have eight legs.

Nationally, there are approximately 650 species of spider and 26 species of harvestmen.

For anyone interested in finding out more information on this diverse and interesting group, please visit the British Arachnological Society’s (BAS) website: www.britishspiders.org.uk. Here, you will find a wealth of information on spiders; and to a lesser extent, harvestmen and false-scorpions. The BAS produces a newsletter and journal three times a year and administers the national spider recording scheme (SRS) (http://srs.britishspiders.org.uk/). The SRS host-pages provide more details on individual species’ ecology and distribution; for example, see the entry for the “garden-cross spider”, Araneus diadematus.

The YNU’s spider recorder also acts as the Area Organiser (for Yorkshire) for the SRS and maintains a host page on Yorkshire spiders.

A recent article in the Yorkshire Naturalist has summarised the status of spiders within Watsonian Yorkshire (Wilson, 2011). There is plenty of scope for discovery, especially within the north and east of the county (vice-counties 61, 62 and 65). However, individuals can contribute, even by sending specimens from their gardens and houses, sheds or allotments – every record counts!

Specimens

Unfortunately, the majority of spiders can only be confirmed to species level through examination of either female’s epigyne or the male’s modified palp (the genitalia). This normally requires the specimen to be (very) still and therefore, well, to put it bluntly, dead! Killing individual spiders will have, except for a very few species (none in Yorkshire), no impact on populations or their conservation. The recorder would therefore welcome specimens (alive or dead) captured within Yorkshire for confirmation or identification. In order for the specimen to be entered in to the SRS database, the following information (as a minimum) is required:

  • date of capture;
  • six (or eight) figure grid reference (the four-figure grid reference, (i.e. 1 km square) is acceptable);
  • geographic name (please try and use a name published on a 1:25,000 or 1:50,000 OS map rather than make one up; or street name and settlement if captured in your back garden/ house)
  • broad habitat (e.g. woodland, or grassland); and additional information if required (e.g. under log, on wall etc).

Specimens can be sent alive or dead in the post addressed to the recorder in a suitable container. If dead, please send in a sealed container and preserve in alcohol. If sending alive, please try and avoid confining more than one individual in each container, otherwise one will eat the others. Please make sure you state whether you want the specimens and/ or the container(s) returned, otherwise I will make a judgement as to whether it is likely that the sender will want them. In return, I will provide a determination and other information as relevant. Please note however, that determinations may take several months as I am a professional ecologist and must prioritise paid work!

Digital Photographs

I am happy to receive digital photographs of specimens taken in the field (or in the ‘lab’) and it is normally possible, at least to identify a species to genus. However, it is rare, except in a few species (e.g. Araneus diadematus) to be able to have any scientific certainty that the specimen is a specific species.

Suggested Reading

For those interested in exploring this group of invertebrates, the following books may be of interest.

Identification

For identification, excluding all but a few ‘money-spiders’ (Linyphiidae), which account for about 40 % of the species in the UK, the Collins Field Guide should be consulted (Spiders of Britain and Northern Europe, by Michael J. Roberts). Whilst this contains illustrations, please bear in mind that confirmation can only be obtained from a specimen, in all but a very few species.

For the aficionado, the book is the two-volume (compact edition) or three-volume edition published by Harley Books (The Spiders of Great Britain and Ireland; again by Michael J. Roberts). This illustrates all the species recorded in the UK except for about ten or so species discovered since its publication in the early 1990s. The serious student would wish to obtain these.

 

Harvestmen are catered for by the Synopses of the British Fauna (New Series) No. 4 (3rd Edition), which provides keys to all but the most recent species of harvestman discovered (in a Sheffield garden) within the UK. The Field Studies Council has also produced an illustrated colour ‘fold-out’ chart to the British species (see http://www.field-studies-council.org/publications/pubs/harvestmen.aspx).

General Reading

    

A readable and good general overview of spiders (and indeed other Arachnids) is the Natural History Museum’s book Arachnids, written by the Museum’s curator, Jan Beccaloni. The lavishly illustrated, mostly by exquisite photographs Spiders. The Ultimate Predators, is also worth purchasing or seeking out from a library. Although long out of print, Bristowe’s The World of Spiders (part of the New Naturalist series) is an excellent read and introduces the student to the British fauna, and wider subjects such as spiders in folklore. A second hand copy is likely to set you back several hundred pounds, so it is probably worth getting it from the library; or purchasing a reprint version from the publishers for approximately £50.00 (hardback). Rainer Foelix’s Biology of Spiders will interest those who want to understand, as the title may suggest, spider biology and is a technical read. Finally, a relatively recent publication is the book edited by M.E. Herbstein on Spider Behaviour, which is actually a series of papers on the subject. The latter two publications are likely to be of interest to those who engage in more serious study of the group.

Websites

In addition to the BAS website, the following may be of interest/ considered useful. The links were accessed on the 8th September 2012. Additional links may be obtained via the BAS website.

http://www.jorgenlissner.dk/default.aspx - illustrated (photographs) of many European species.

http://ednieuw.home.xs4all.nl/Spiders/spidhome.htm - similarly illustrated spiders of north-west Europe.

http://www.araneae.unibe.ch/index.html - an interactive key to the spiders of Europe (based on the German publication Spinnen Mitteleuropas (by Stefan Heimar and Wolfgang Nentwig)).

http://research.amnh.org/iz/spiders/catalog/INTRO2.html - the world spider catalogue, maintained by Norman Platnick. If you want to know how many species have been described globally, their name and distribution, this is the place to come to (43,244 species as of June 2012).

Richard Wilson, September 2012.

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