Thanatus
C. L. Koch, 1837
false crab spiders, running crab spiders
Species Guides
6- Thanatus altimontis
- Thanatus coloradensis
- Thanatus formicinus(Running Crab Spider)
- Thanatus rubicellus
- Thanatus striatus(Striped Running Crab Spider)
- Thanatus vulgaris(Cricket Thief Spider)
A of running crab spiders ( Philodromidae) described by C.L. Koch in 1837. reach 5–6 mm in body length and are primarily ground-dwelling hunters found on low vegetation and open surfaces. The genus is distinguished from similar Philodromus by arrangement differences and is characterized by a prominent leaf-like cardiac mark on the . Thanatus overwinter as adults and are among the most abundant active spiders in early spring in temperate regions.
Pronunciation
How to pronounce Thanatus: /θəˈneɪtəs/
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Identification
Distinguished from the similar Philodromus by differences in arrangement. Separated from Tibellus (also Philodromidae) by a more robust body and different stripe pattern on the ; Tibellus has a more elongated body and hunts on stems and leaves rather than the ground. Distinguished from ground crab spiders (Xysticus, Thomisidae) by family-level traits including leg posture and eye arrangement. The clear leaf-like cardiac mark on the is a key visual feature.
Images
Habitat
Low vegetation and ground-level substrates in open . Frequently encountered on concrete paths, sidewalks, and bike trails where surfaces warm faster than soil, providing basking opportunities. Found in grasslands, forest edges, and disturbed habitats including vacant lots.
Distribution
Present across most of Europe; records from Denmark, Norway, and Sweden confirmed. Also documented in North America including Colorado and other regions. The contains 96 as of September 2025 with broad distribution in temperate regions.
Seasonality
Active primarily in spring, with and becoming abundant during early spring months (March–April in temperate North America). Adults may be encountered into November in regions with unseasonably warm weather.
Life Cycle
Overwinters as . Reproductive timing suggests spring mating activity. Females produce sacs; specific details of egg and spiderling development not documented in available sources.
Behavior
Ground-dwelling hunter that does not build webs to capture prey. Has been observed basking on warm surfaces such as concrete and asphalt to elevate body temperature. Individuals have been observed engaging in ballooning (climbing vertical objects to catch wind for ) in spring and fall.
Ecological Role
of small arthropods in ground-level and low vegetation . Serves as prey for spider wasps including Priocnemis minorata ( Pompilidae), which has been documented paralyzing Thanatus spiders as for their larvae.
Human Relevance
Frequently encountered by pedestrians on sidewalks and bike trails, making it one of the more commonly observed spider in urban and suburban environments during spring. Harmless to humans; does not possess medically significant venom.
Similar Taxa
- PhilodromusSame (Philodromidae) and similar general appearance; distinguished by arrangement differences
- TibellusSame with similar coloration; Tibellus is more slender, hunts on vegetation rather than ground, and has different stripe pattern
- XysticusSimilar ground-dwelling habit and appearance; different (Thomisidae) with distinct arrangement and leg structure