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The Indian Ocean giant tortoise Testudo gigantea on Aldabra
Author(s) -
Gaymer R.
Publication year - 1968
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1968.tb01668.x
Subject(s) - tortoise , atoll , biology , indian ocean , ecology , gastropoda , zoology , oceanography , reef , geology
The Indian Ocean giant tortoise survives on Aldabra, an atoll north‐west of Madagascar. The Bristol Seychelles Expedition estimated the total numbers as 33,000 during visits in 1964 and 1965. Growth and movements were recorded during marking experiments. The growth rate with size is plotted, the time scale being derived from the number of rings on the shields of the shell; and the growth curve is compared with that for captive tortoises. Variation in many characters of supposed taxonomic value is explained as the influence of environmental factors on the normal growth pattern, and of non‐adaptive differences expressed during adult life. The present separation of north and south Aldabra, and Seychelles forms is not supported. An explanation is suggested for the uniformity of shape among tortoises. Observations were made on the feeding, diurnal movements and mortality of tortoises on Aldabra.