Impacts of thermal stress on the histological arm regeneration of brittle star Ophiocoma scolopendrina (Lamarck, 1816)

Investigation the effects of thermal stress on the arm regeneration of brittle star Ophiocoma scolopendrina and comparing them with samples regenerated in normal temperature.

In this study, brittle star samples of O. scolopendrina collected from Qeshm Island were anesthetized with 3.5% Mgcl2.6 (H2O) solution. Two arms were cut from each star. The brittle stars were divided into 6 groups: three aquariums for control samples (25 ℃) and three aquariums for thermal treatment samples (32 ℃). Then, at 24, 72 hours, 14 and 21 days post amputation, their arms have been amputated again. After fixing and decalcification, the samples were prepared and examined under a light microscope.

Histological studies of the regeneration process in thermal-treated samples showed that the rate of regeneration in them up to 14 days is faster than the control samples, but from this period onwards the temperature tolerance was beyond their tolerance and led to autotomy and disk destruction of these brittle stars. On the other hand, one of the interesting results of this research was that brittle stars under heat stress reconstructed their miniature arm under the epidermis covering the wound site, which may be a mechanism to protect the delicate and sensitive reconstructed arm.

Due to the increase in metabolic rate, the samples of thermal treatment showed more speed in the repair and regeneration processes, but with the prolongation of the time period, the stars underwent autotomy and perished.