Linyphiidae Blackwall, 1859
Linyphiidae Blackwall, 1859
Sheetweb weavers are one of the biggest families of spiders in the world, and they are found all around the world. There are at least 60 species in Michigan, and probably more that are not yet known.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native )
Sheetweb weavers are small, dark, shiny spiders that build interesting webs. They are less then 8 mm long. Like all spiders they have two body-segments, a cephalothorax in front and an abdomen behind. They have eight legs, all attached to the cephalothorax. On the front of the cephalothorax are the fangs, the eyes, and two small "mini-legs" called pedipalps. The pedipalps are used to grab prey, and in mating, and are much bigger in male spiders than in females. Sheetweb spiders have eight eyes in two rows of four. They have fangs that they use to bite their prey with, and venom glands. On their fangs are rough spots that they can rub together to make sounds.
It is impossible for us to tell the difference between a sheetweb weaver and a cobweb weaver except by looking at their webs (see below for more on sheetwebs).
Range length: 1.5 to 8.0 mm.
Other Physical Features: bilateral symmetry
Sheetweb weavers are found in all kinds of habitats: anywhere there are small insects and at least a little vegetation to build their webs on.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: tundra ; taiga ; desert or dune ; chaparral ; forest ; rainforest ; scrub forest ; mountains
Spiders in this family spin small horizontal sheets of webbing, or domes (see the pictures for an example). They hang upside-down underneath the web, and when a small Insecta or other animal walks across it, they bite through the silk, then grab their prey and pull it through to eat it.
Sheetweb weavers hide underneath their webs, and sometimes make two layers of web and hide between them for protection. If disturbed by a larger animal they quickly drop down into nearby vegetation to get away.
- other Araneae
- small Amphibia
Life History and Behavior
Communication and Perception
These spiders have special structures on their fangs that they can rub together to make sounds to communicate with. They probably also use web vibrations, and certainly use taste and smell to communicate.
These spiders hatch from eggs, and the hatchlings look more or less like grown-up spiders, though sometimes their colors change as they age. To grow they have to shed their exoskeleton, which they do many times during their lives.
These little spiders probably don't live much longer than a year.
Breeding interval: After mating, female sheetweb weavers lay eggs.
Breeding season: Probably Spring, Summer, or Fall
Key Reproductive Features: sexual ; fertilization (Internal ); oviparous
Females hide their eggs in special egg sacks made of silk, sometimes attached to their webs (and probably guarded by her) and sometimes just stuck to twisted grass stems and left alone.
Parental Investment: female parental care
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:13200
Specimens with Barcodes:12751
Species With Barcodes:788
No sheetweb weavers are known to be in danger, but there are still many species out there we don't know anything about.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Positive
These are harmless little spiders that might help keep the population of small insects under control, but don't have any strong direct effects on humans.
Linyphiidae is a family of very small spiders, including more than 4,300 described species in 578 genera worldwide. This makes Linyphiidae the second largest family of spiders after the Salticidae. New species are still being discovered throughout the world, and the family is poorly known. Because of the difficulty in identifying such tiny spiders, there are regular changes in taxonomy as species are combined or divided.
Spiders in this family are commonly known as sheet weavers (from the shape of their webs), or money spiders (in the United Kingdom, Ireland, Australia, New Zealand, and in Portugal, from the superstition that if such a spider is seen running on you, it has come to spin you new clothes, meaning financial good fortune).
Common genera include Neriene, Lepthyphantes, Erigone, Eperigone, Bathyphantes, Troglohyphantes, the monotypic genus Tennesseellum and many others. These are among the most abundant spiders in the temperate regions, although many are also found in the tropics. The generally larger bodied members of the subfamily Linyphiinae are commonly found in classic "bowl and doily" webs or filmy domes. The usually tiny members of the Erigoninae are builders of tiny sheet webs. These tiny spiders (usually 3 mm or less) commonly balloon even as adults and may be very numerous in a given area on one day, only to disappear the next. Some males of the erigonines are exceptional, with their eyes set up on mounds or turrets. This reaches an extreme in some members of the large genus Walckenaeria, where several of the male's eyes are placed on a stalk taller than the carapace.
A few spiders in this family include:
- Bowl and doily spider, Frontinella communis
- Filmy dome spider, Neriene radiata
- Blacktailed red sheetweaver, Florinda coccinea
Spiders of this family occur nearly worldwide. In Norway many species have been found walking on snow at temperatures of down to -7 °C.
- Cirrus Digital, Sheetweb Spider - Drapetisca alteranda
- Hormiga 2000
- RSPB Birds magazine, Winter 2004
- Hormiga, G. (1998). The spider genus Napometa (Araneae, Araneoidea, Linyphiidae). Journal of Arachnology 26:125-132 PDF
- Hormiga, Gustavo (2000): Higher Level Phylogenetics of Erigonine Spiders (Araneae, Linyphiidae, Erigoninae). Smithsonian Contributions to Zoology 609. (160 pages) PDF
- Bosselaers, J & Henderickx, H. (2002) A new Savignia from Cretan caves (Araneae: Linyphiidae). Zootaxa 109:1-8 PDF
- Hågvar, S. & Aakra, K. 2006. Spiders active on snow in Southern Norway. Norw. J. Entomol. 53, 71-82.
- Platnick, Norman I. (2007): The world spider catalog, version 8.0. American Museum of Natural History.
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