cobweb spiders vs Common Wall Cress

Steatoda grossa compared with Arabidopsis thaliana

Taxonomic Classification

Rank	cobweb spiders	Common Wall Cress
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Arthropoda (Arthropods)	Magnoliophyta (Flowering Plants)
Class	Arachnida (Arachnids)	Magnoliopsida (Dicots)
Order	Araneae (Araneae)	Brassicales (Brassicales)
Family	Theridiidae	Brassicaceae
Genus	Steatoda	Arabidopsis
Species	Steatoda grossa	Arabidopsis thaliana

Conservation Status

cobweb spiders

LC — Least Concern

Common Wall Cress

LC — Least Concern

Physical Characteristics

Attribute	cobweb spiders	Common Wall Cress
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

cobweb spiders

Habitat

Typically found in terrestrial habitats from forests to deserts.

Range

Widely distributed across Africa (South Africa), Europe (29 countries), North America (Canada, United States), and South America (Ecuador).

Common Wall Cress

Habitat

Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

Range

Widely distributed across Africa (South Africa), Asia (Japan, Taiwan), Europe (11 countries), North America (Canada, United States), Oceania and the Pacific (Australia), and South America (Brazil, Chile).

cobweb spiders

The false black widow (Steatoda grossa) is a cosmopolitan cobweb spider in the family Theridiidae, often mistaken for the true black widow due to its similarly dark, globose abdomen, though it lacks the red hourglass marking. Females reach 6–10 millimeters in body length and display a deep purplish-brown to nearly black coloration with faint pale markings on the dorsal abdomen. Originally native to western Europe, Steatoda grossa has spread globally through human commerce, establishing populations in Australia, New Zealand, North America, and other regions where it thrives in human structures including homes, sheds, and outbuildings. The spider constructs a persistent, tangled cobweb in sheltered corners and recesses, where it captures woodlice, ants, beetles, and other arthropods—notably targeting invertebrates that many other spiders avoid. The venom of S. grossa causes steatodism, a syndrome of localized pain, sweating, and systemic discomfort that is rarely serious but can cause significant distress. Interestingly, the antivenin produced for Latrodectus (true widow) spider bites has been shown to effectively treat Steatoda envenomations, underscoring the phylogenetic relatedness of these genera. Females produce several egg sacs during a season, each containing dozens of eggs wrapped in distinctive silken cocoons. The species is classified as Least Concern given its expanding global distribution facilitated by human activity.

Common Wall Cress

Arabidopsis thaliana, commonly known as common wall cress or thale cress, is a small annual flowering plant in the family Brassicaceae native to Eurasia and Africa, and now naturalized in North America, Australia, and other temperate regions worldwide. The species has become one of the most important model organisms in plant biology and genetics, owing to its small genome size, short generation time of approximately six weeks, prolific seed production, and ease of laboratory cultivation. Arabidopsis thaliana was the first plant to have its complete genome sequenced, in 2000, revolutionizing our understanding of plant molecular biology, development, and physiology. In nature, it typically grows in rocky outcrops, disturbed sandy soils, walls, roadsides, and waste ground, tolerating poor nutrient conditions and a wide range of climates. The plant produces a basal rosette of small ovate leaves, followed by an erect flowering stem bearing tiny white four-petaled flowers and slender silique seed pods. Despite its modest appearance, Arabidopsis thaliana has facilitated thousands of scientific discoveries in plant genetics, epigenetics, and stress responses. The species is currently assessed as Least Concern by the IUCN. Biological traits such as average lifespan, plant height up to 30 centimeters, and seed output are well-characterized in laboratory settings.