Non-lethal imaging techniques for crab spermathecae

Techniques for collecting information on spermathecae without dissection were evaluated on the giant crab Pseudocarcinus gigas. Techniques tested were: biopsy, ultrasound, conventional x-radiography, computerized tomography (CT) scans, and magnetic resonance imaging (MRI). Attempts at biopsy and ultrasound imaging were unsuccessful. Spermathecae were imaged by x-radiography, although resolution was poor, suggesting that it can be applied only to gain general information, such as determining whether mating has occurred. High resolution images were produced with CT and MRI. Resolution by MRI is of such detail that internal structure of spermathecae is imaged. Nonlethal techniques allow animals to be used repeatedly, which permits monitoring of changes during mating, sperm storage, and extrusion.