Small World Discoveries
by Tony Enticknap - tickspics
Taking a close look at insects and other small species that can be found in and around East Dorset and the New Forest ...
ARACHNIDA
ARACHNIDA is a high-ranking classification, known as a 'class', that taxonomically sits alongside INSECTA as one of the major subdivisions of ARTHROPODA. It comprises various groups of eight-legged, mainly terrestrial, invertebrates.
My primary interest is with ARANEAE (spiders) as featured here and OPILIONES (harvestmen) that have their own page, but ARACHNIDA also includes two further groups that I want to cover at some point. They are the ACARI, now regarded as a subclass, consisting the ACARIFORMES (mites) and PARASITIFORMES (ticks) and hopefully, if I can find some, the PSEUDOSCORPIONES (false scorpions). These tiny, primarily soil and leaf-litter dwelling creatures will be looked at in some form within the final section of the website.
ARANEAE (Spiders)
Spiders have a two-part body comprising the cephalothorax (the anterior portion, combining the head and thoracic regions with the dorsal surface protected by the carapace) and the abdomen, which are separated by a 'waist-like' constriction where they are joined, known as the pedicel. They have four pairs of legs, which are attached to the underside of the cephalothorax, and three, or in most cases, four pairs of eyes. At the front of the head they have a pair of sensory pedipalps that resemble short legs, which are enlarged in the males for sperm transfer. Being predatory, the mouthparts have the chelicerae (jaws) modified into fangs fed from venom glands, which makes some species harmful to humans. The tip of the abdomen has spinnerets served by silk glands. The silk that's produced can be used for several purposes including the construction of webs and egg-sacs or, in some species, to form long threads that catch the wind and allow long-distance travel known as 'ballooning'.
There are around 650 established British species according to the latest checklist (Lavery, 2019), which are classified within 38 families that range considerably in size from those with just one or two species up to the largest, the small Money spiders (Linyphiidae), with over 280 species, which is 43% of the total. A number of these families, group species by the construction of their webs, such as Funnelweb (Agelenidae), Orbweb (Araneidae) and Tubeweb (Segestriidae), whereas others, including Crab (Thomisidae), Wolf (Lycosidae) and Jumping (Salticidae) for example, may be related to the spiders' general appearance or habits. Family names are followed by spiders; always in lowercase, as in Running crab spiders (Philodromidae) and Long-jawed orbweb spiders (Tetragnathidae), as only the first letter of the name is capitalised.
Most of the frequently observed species have been given a common name, whilst others may have a name covering all the species within the genus, for example Jumping spiders include Salticus - 'zebra spiders', and Heliophanus - 'sun jumping spiders'. A common name relating to a specific species, such as the Marbled Orbweb Spider or Flower Crab Spider, is fully capitalised, whereas a 'collective generic name' is not.
Although it would be nice to put a 'name' to every individual photographed, it has to be appreciated that there are a large number of related species that simply cannot be distinguished from photos and, consequently, must be identified as, Araniella sp., Pardosa sp.,etc. And, when it comes to official recording, there are many species that cannot be positively identified without microscopic examination, which inevitably results in skewed distribution data as casual observers like myself can't contribute. However, there are often factors that may include certain features or characteristics, or habitat, time of year, and location and rarity, that can provide a strong indicator that a particular species may be probable or the most 'likely' candidate, which is absolutely fine for personal records if qualified as such, which is when the cf. qualifier is applied, as in Metellina cf.segmentata for example.
Although I've now gained an interest in spiders, I rarely go hunting for them so most sightings are chance encounters while out looking for insects. I also try to photograph any that I discover in the garden, which in itself has proved interesting as I didn't realise that so many different species could be found in such a small area. My current tally is around eighty-five species, which isn't a bad number all considering. And, it's nice to have seen a few that are considered uncommon or nationally scarce (NS). Obviously, I'll keep adding to the list, but I suspect that new discoveries may now be few and far between.
The species that I have seen and photographed are shown below in taxonomical order. Each thumbnail image links to an associated 'family account', which in some cases is split down into separate accounts covering specific species or genera. Each of these accounts provides additional information and further photos that can be enlarged.
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Atypidae (Purseweb spiders)
Pholcidae (Cellar spiders)
Dysderidae (Woodlouse spiders)
Theridiidae (Comb-footed spiders)
Tetragnathidae (Long-jawed orbweb spiders)
Araneidae (Orbweb spiders)
Lycosidae (Wolf spiders)
Pisauridae (Nurseryweb spiders)
Agelenidae (Funnelweb spiders)
Hahniidae (Lesser cobweb spiders)
Dictynidae (Meshweb spiders)
Amaurobiidae (Laceweb spiders)
Anyphaenidae (Buzzing spiders)
Clubionidae (Sac spiders)
Cheiracanthiidae (Yellow sac spiders)
Gnaphosidae (Ground spiders)
Philodromidae (Running crab spiders)
Thomisidae (Crab spiders)
Salticidae (Jumping spiders)
Linyphiidae (Money spiders)
Original list created Jan.22 | updated Jan.25 (v.5)