Spiders
Now is a good time to spot spiders in the water meadows, when fine Autumn mists mark out their webs with tiny water droplets. The beautiful orb weaver spider pictured was found in Ram Meadow enjoying the warmth of October sunshine. We may also notice more spiders in our homes at this time of year too, such as the giant house spider ((Eratigena species), which live indoors year-round (the clue is in the name), or “daddy long legs” (Pholcus phalangioides) pictured with spiderlings. Autumn is breeding season for spiders, and males are out and about looking for a mate.
In many spiders, males mature more quickly than females. Mature males spin a small silk pad on which they deposit sperm. They then draw the sperm into the pedipalps (the two appendages at the front of the head that look a bit like antennae), which act like syringes. Males abandon their webs (if they make one) and go in search of females. Courtship is very long in some species, very brief in others, and differs in detail depending on whether the species builds webs. In others it includes dancing or giving gifts. The culmination of courtship is the locking of the male pedipalp to the female epigyne (external genital structure), and the transfer of sperm.
In some species the females lay eggs within a few days of mating, in others it happens after several months. The eggs are produced from the genital opening and are wrapped in silk. In some species the female immediately abandons the egg sac while in others she guards it until the young emerge. Some carry their egg sacs around with them, ensuring their safety and providing the best possible conditions for the eggs’ development. In a few British spiders the female even feeds her young for a short while on regurgitated food, like many birds do. The newly-hatched young resemble their parents in every way except for sexual organs and possibly colour. They grow in size by moulting – shedding their ‘skin’ (exoskeleton) from time to time. The number of moults required to mature varies between species, as does the overall lifespan. Many spiders live for only a few months as adults, while others like the female large house spiders can survive for a couple of years.
Although the sight, or even thought, of spiders makes many people uncomfortable, says the British Arachnological Society, we should remember that British spiders are largely harmless and do lots of good for people. Spiders are so numerous that they are a vital part of the ecosystems on which we all depend. Over 800 can be found in a square metre of grassland, and there are about 650 species in the UK. They catch and eat many of the insects (houseflies, midges, wasps) which bother us in our homes and gardens and help to prevent the build-up of agricultural pests, reducing the need for artificial pesticides.
Libby Ranzetta
Bury Water Meadows Group trustee
photos
orb weaver by Libby Ranzetta
daddy long legs by Jillian Macready