NOTES ON THE BEHAVIOR OF 
THALASSIUS SPINOSISSIMUS 
(ARACHNIDA: ARANEAE: PISAURIDAE) 
By Petra Sierwald 
Delaware Museum of Natural History, Wilmington, DE 19807 
Introduction 
The present paper reports predatory, copulatory and parental 
behavior as observed in Thalassius spinosissimus (Karsch, 1879) in 
its natural habitat and in the laboratory. Spiders of this species have 
been reported to hunt on the surface of freshwater and to catch fish 
(Abraham 1923, Lawrence 1970). Thalassius spinosissimus is the 
most widespread and commonly collected species in the genus. It is 
distributed over Africa south of the Sahara. 
Observations 
Habitat 
Thalassius spinosissimus inhabits banks with lush vegetation 
close to freshwater. A population of a small freshwater pond in an 
indigenous forest five miles north of Pietermaritzburg (Natal, South 
Africa) was observed for one year (1980). The abundance of T. 
spinosissimus was high (2. 8-6.4 spiders per m 2 in the study area; 
recorded at 20 visits at the study side during the summer season). 
The distances between individuals hunting on the water surface va- 
ried between 5 and 20 cm (distances were measured between the tips 
of extended legs of individuals; recorded 1 1 times). 
Life cycle 
At the study site, T. spinosissiumus overwintered from May to 
September; specimens were found immobile hiding under rocks and 
logs near the pond. The active season is the summer between 
October and May. Adults were found during November through 
March; in April and May only juveniles were observed. 
Manuscript received by the editor March 15, 1988. 
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