SCALING OF SUPPORTIVE TISSUE MASS

The allometric relationship between supportive tissue mass and total body mass has been investigated in spiders, freshwater mollusks, and bird eggs. These results were compared with data available for birds, land mammals, whales, and a rattlesnake. The comparison indicates that the change in supportive tissue mass as a function of change in total body mass is surprisingly similar in all the organisms considered: a ten-fold change in total body mass is accompanied by a thirteen-fold change in supportive tissue mass. Supportive tissue makes up a largerfraction of the total mass in organisms with external skeletons than in those with internal skeletons. Within the latter group, the vertebrates, the amount of total mass is similar, except for the whales. When corrected for true body mass, whales contain smaller amounts of bone (16-26%) than do land mammals, a difference much less than previously reported. In no case did support tissue mass exceed 20 per cent of total body massfor mobile organisms. © 1979, University of Chicago Press. All rights reserved.