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Umdoni, KwaZulu-Natal, South Africa
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This subtidal aggregation of T.g.elatensis demonstrates the high color variablity within this subspecies. Coloration of spines, tube-feet and pedicellaria ranges between white and black with no dominance of any color combination. to protect against high light intensity and camouflage they carry pebbles and sea-grass leaves.
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A living T. g. elatensis showing Type B pollution-induced deformity in Eilat, Red Sea: It showed mainly as an extreme apical collapse . It was apprently caused by chemicals ejected from a hotels laundry into an artificial lagoon. 2/3 of the population showed this deformity. This deformity was described by Dafni (1983b). It is still shown occasionally in small shore streches, apparently affected by polluted waters.
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Tests of Red Sea T. g. elatensis showing the rather smooth appearance of the test. arrows show the paucity of spine tubercles - less than 1 spine for each interambulacral plate (most oceanic Tripneustes - T. gratilla, T. depressus and T. ventricosus - all show at least one primary spine for each plate). The wide space between the ambulacra is densely covered by pedicellaria, which are poisonous the a certain degree (some people become allergic to it).
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Type A Deformed test of a T.g.elatensis showing exaggerate vertical growth, and "pinched" ambulacra, simultaneusly in all five ambulacra. A detailed descriotion of these deformities is shown in Dafni, 1980 and in Dafni & Erez 1987a,b.
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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
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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.
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Santa Cruz, California, United States
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Santa Cruz, California, United States
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Santa Cruz, California, United States
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