Type A deformity idue to pollution in T. g. elatensis in Eilat, Red Sea: It showed mainly as exaggrated H/D ratio. Here, a living urchin of ca 35 mm diameter, showed H/D = 1.2 proportion. This deformity was shown by over 1/2 of the population of T. g. elatensis in the shore next to the outfall of hot and saline seawater ejected from a combined power and desalination plant. Another picture shows the dried out test of a similar deformed urchin showing a skeletal abnormality such as "pinched" ambulacra, simultaneusly in all five ambulacra. A detailed descriotion of these deformities is shown in Dafni, 1980 and in Dafni & Erez 1987a,b
A Typical northern Red Sea T.gratilla elatensis. It is unique in several aspects: It is flatter than T.g.gratilla, It has less spines, and many more pedicellaria, covering its interambulacral plates. Coloration variable- spines, tubefeet and pedicellaria coloration each range from pure white to pitch black (in this picture spines are reddish, as well as tubefeet, and pedicellaria are white - all combinations occur in nature), This variety was observed througout the entire north and middle Red Sea. In Eilat, this sea urchin was prone to mass sea pollution that affected the calcification processes as well as the softer collagenous tissues activity, causing extreme deformities. The deformities were of two types - type A exaggerated H/d ratio and showing severe skeletal deformities; and type B, aboral depressions in which the entire aboral part of the test collapsed. These deformities disappeared when the poluting agant were removed.
