Social cobweb spiders

Anelosimus

Classification

Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Theridiidae
Genus: Anelosimus

Pronunciation

How to pronounce Anelosimus: //ænəˈloʊsɪməs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Images

Cocoon web of host spider Anelosimus studiosus for parasitic wasp Zatypota solanoi by William G. Eberhard. Used under a CC BY 3.0 license.

Social Cobweb Spider - Anelosimus studiosus, Loxahatchee National Wildlife Refuge, Boynton Beach, Florida by Judy Gallagher. Used under a CC BY 2.0 license.

Cobweb Spider - Anelosimus studiosus, Anhinga Trail, Everglades National Park, Homestead, Florida by Judy Gallagher. Used under a CC BY 2.0 license.

Summary

The genus Anelosimus, known as social cobweb spiders, contains over 74 described species. They range from solitary to highly social forms, particularly in the Americas where certain species exhibit extensive communal living. Anelosimus eximius, one of the best-studied species, exemplifies the complexity of social behavior in this genus.

Physical Characteristics

Anelosimus spiders have a notched red or brown band on their abdomen, which is dark when preserved in alcohol. Laterally, the abdomen has a white band and/or white blotches. Specimens range in size from 1.8 to 7.5 millimetres (0.071 to 0.295 in). Individuals in this genus lack a colulus.

Identification Tips

Look for the notched band on the abdomen and the presence of lateral white bands or blotches. Size can vary from 1.8 to 7.5 mm.

Habitat

Anelosimus species occupy a variety of habitats ranging from tropical to warm temperate areas, particularly in lowland tropical forests for highly social species.

Distribution

Anelosimus is a cosmopolitan genus found worldwide, with specific presence in the Americas, including Southeastern Arizona and Southern California.

Diet

Anelosimus species primarily consume small insects and other small invertebrates, as is characteristic of cobweb spiders.

Life Cycle

Details on the specific life cycle of Anelosimus species are not provided, but they are known for variations in social behavior with quasisocial species exhibiting complex interactions.

Reproduction

Social Anelosimus species generally show female-biased sex ratios, with an observation of up to 10 females per male in some studies.

Ecosystem Role

Anelosimus spiders may play a significant role as predators in their ecosystems, helping to control insect populations.

Evolution

Anelosimus is a key group in the study of sociality and its evolution in spiders, with sociality independently arising several times across different species.

Similar Taxa

Misconceptions

Anelosimus is often thought to exclusively be social; however, the genus includes solitary and subsocial species as well.