Estimation of total hemolymph volume in the horseshoe crab Limulus polyphemus

Abstract

Biomedical companies extract blood from the horseshoe crab, Limulus polyphemus, for the production of Limulus Amebocyte Lysate, used worldwide for detecting endotoxins in injectable solutions and medical devices. Despite the extensive use of horseshoe crabs by the biomedical industry, total hemolymph volume for this species is not known. The hemolymph volume of 60 adult horseshoe crabs was estimated using an inulin dilution technique. Blood volume of the horseshoe crab represented as a percentage of wet body weight was 25 ± 2.2% for males and 25 ± 5.1% (mean ± SD) for females. Relationships between hemolymph volume and weight (p = 0.0026, r 2 = 0.8762), hemolymph volume and prosomal width (p < 0.0001), and hemolymph volume and inter-ocular width (p < 0.0001) were observed. No significant differences were observed between males and females. The relationship of animal size and hemolymph volume can be used to predict how much blood can be drawn from horseshoe crabs used by the biomedical industry, and can be of further use in future bleeding mortality studies.