LIFE CYCLE OF MALE TARANTULA 



spiders of various sizes will probably 

 serve to make out a reliable account of the 

 entire life cycle. 



Measuring the total length of the 

 spider at certain intervals of time is 

 obviously not a very exact way of observ- 

 ing the growth; for the abdomen may 

 vary in size between fairly wide limits. 

 The increase in the length of the carapace 

 is perhaps a more reliable indication of 

 the growth; but since the records of this 

 have been kept for only a few years, they 

 are not suitable for use here. 



The rate of growth of tarantulas from 



in the laboratory are more favorable than 

 those out of doors. The unusual growth 

 that it made during its first year and a 

 half in the laboratory lends support to 

 this assumption. At the age of eight- 

 and-a-half years it measured 37.4 mm. 

 RTi when first measured was 37.5 mm., 

 and therefore fitted well into the age 

 of eight-and-a-half years. This male 

 reached maturity last fall (192.7) at an 

 estimated age of eleven years. There is a 

 possibility that his age was one year less 

 than that, but it is more likely that he 

 was older, perhaps twelve years. 



The tarantulas probably do practically 

 all their hunting right in front of their 

 holes, where they patiently wait night 





Annual Increase in Size 

 (In pttllimeters) 





YEAR 



YEARS 



2* 



YEARS 



3} 



YEARS 



4 J- 



YEARS 



6 



YEARS 



6§ 



YEARS 



YEARS 



8j 



YEARS 



YEARS 



10| 

 YEARS 



Hi 

 YEARS 



WH 2 



6.8 



IO.S 

 IO. O 



16.6 

 13-3 



I7.6 



18.O 



z8.o 



32-5 



35'* 



37-4 

 37-5 



46.4 



48.5 





Mcl 6 





WF 





RTi 



47-3 





Measurements were made during the winter, from the last week in December till the first week in February, 

 except the 6-year record, which was taken in the following July. 



the time of hatching until the age of three- 

 and-a-half years has been observed (see 

 accompanying table), as has that of 

 somewhat older tarantulas of various 

 sizes. By putting these figures together, 

 a table has been constructed which 

 represents with a fair degree of accuracy 

 the annual growth throughout the entire 

 life cycle of a male tarantula. 



Regarding the estimate of the ages of 

 the various spiders represented in the 

 table, some explanation is perhaps desir- 

 able. Although WF, when first measured, 

 was 18 mm. long and but slightly longer 

 than Mclc at the age of three-and-a-half 

 years, the former has been estimated at a 

 year older, for the reason that conditions 



after night for a suitable beetle, cricket, 

 or other insect. They locate their prey 

 wholly by the sense of touch. Thus a 

 cricket may come within a centimeter of 

 where the tarantula is waiting, and be 

 perfectly safe; however, as soon as one 

 touches the other, the cricket is very 

 speedily brought in reach of the fangs 

 and consumed. From this method of 

 hunting, it seems obvious that the taran- 

 tulas must often undergo longer or shorter 

 periods of fasting. And from observa- 

 tions in the laboratory, it appears that 

 Nature has equipped them weil for this; 

 for they can easily go without food for a 

 month or six weeks and probably longer. 

 As a result of the fasting, the time required 





