220 
Psyche 
[September 
Zoology. Sicarius sp. i was collected under a log in a pasture near 
Santiago del Estero, Argentina, on April 2, 1965. Sicarius sp. 2 was 
found under a rock at the base of a loma in the desert south of 
Lima, Peru on February 7, 1965. 
Detailed observations and timings were made by analyzing, frame 
by frame, 16 mm. motion pictures (24fps) of the complete, self-bury- 
ing activity. Several runs of each species were analyzed and twelve 
frames from one take of Sicarius sp. 1 are presented in Plates 1 and 2. 
The basic pattern of behavior observed was similar in both cases 
though the species are distinct. This pattern is outlined in Table 1 
and illustrated in Figures 1-12. 
The first six steps (Table 1) are invariable, qualitatively, though 
time duration of each action and period between actions varies a 
great deal. In digging, the first two pairs of legs dig while the hind 
pairs stabilize the spider (Fig. 1). Positioning of legs (Step 6) varies 
from less than a second to four seconds. 
Step 7 consists of the first pair of legs alternately throwing sand 
over the body and exposed portions of the 4th legs (arrow in Fig. 6) 
from 6-15 times (approx. 4 times/second). Tufts of hairs on abdo- 
men (arrow in Fig. 2) aid in holding the sand-covering in place. In 
Sicarius sp. 2 this action is split into two sections. First the throwing 
of sand, then a pause of about 30-120 seconds, then a continuation of 
Table 1. Self-burying in Sicarius sp. 1 (duration 
in seconds, of each step within parentheses). 
Step 1. Digs hole (1.0) Fig. 1 
Step 2. Jumps into hole (0.2) Fig. 2 
Step 3. Adjusts abdomen 
(0.4) 
Step 4. Adjusts 4th legs (0.6) Fig. 3 
Step 5. Buries 4th legs partly 
(0.2) Fig. 4 
Step 6. Positions legs (2.0) Fig. 5 
Step 7. 1st legs cover body 
and 4th legs with sand 
(1.8) Fig. 6 
Step 8. Buries 1st legs partly 
(0.6) Fig. 7 
Step 9. 2nd left leg throws sand 
forward (0.3) Fig. 8 
Step 10. Buries 2nd left leg (0.5) 
Step 11. 2nd right leg throws 
sand forward (0.2) Fig. 9 
Step 12. Buries 2nd right leg 
(0.6) Fig. 10 
Step 13. 3rd left leg throws sand 
forward (0.2) Fig. 11 
Step 14. Buries 3rd left leg (0.4) 
Step 15. 3rd right leg throws 
sand forward (0.2) 
Step 16. Buries 3rd right leg 
(0.4) Fig. 12 
Explanation of Plate 16 
Figs. 1-6. Self-burying of Sicarius sp. 1, steps 1, 2, 4-7 (see Table 1 
and text for details). 
