The telson is used in turning the crab over when it is upside down and in passive defense. The telson can be used to protect the gills while the crab is on it's back. In a way, the telson of the horseshoe crab resembles the tail of another marine animal, the stingray. Unlike a stingray, the horseshoe crab posses no stinger or poison in it's tail. In adult horseshoe crabs the difference of the sexes is easy to distinguish.
Males are usually smaller than female crabs.
The tip of the male first walking leg modified to form the monodactyls, one fingered, clasper. The tip of the female first walking leg remains the same didactylus, two fingered, pinchers. The horseshoe crab is a docile animal and can easily be handled for a closer examination. While handling the horseshoe crab always take care not to injure the animal. Horseshoe crabs are important biomedically and a great natural resource.