be the same compound as Contractin A, since both have the same molecular weight of 18,000 Da and an almost identical N-terminal sequence. In addition to these toxins, lectins have also been isolated from flower urchin venom. Among them is SUL-I, SUL-II, SUL-IA, and SUL-III (SUL stands for "sea urchin lectin"). These lectins may be valuable as research tools for investigating the functions of cell processes. Envenomation mechanism Unlike most other venomous sea urchins, flower urchins and related toxopneustids do not deliver their venom through spines. Instead, the venom is administered through the flower-like globiferous pedicellariae. If undisturbed, the tips of the globiferous pedicellariae are usually expanded into round cup-like shapes. They possess tiny sensors on their inside surfaces which can detect threats by touch and chemical stimuli. When agitated or brushed against by a potential threat, the pedicellariae will immediately snap shut and inject venom. The claws of the pedicellariae may also break off from their stalks and adhere to the point of contact, retaining the ability to continually inject venom for several hours. The potency of the pedicellarial venom is believed to be directly related to the size of the pedicellariae. Thus individuals with larger globiferous pedicellariae are considered to be more dangerous than individuals with more numerous but smaller globiferous pedicellariae. Effects on humans In 1930, the Japanese marine biologist Tsutomu Fujiwara accidentally envenomated himself with seven or eight flower urchin pedicellariae while working in a fishing boat. He described his experience in a paper published in 1935: There have been reports of fatalities resulting from flower urchin envenomation. One such report was the purported drowning of a pearl diver after being rendered unconscious from accidental contact with a flower urchin. But it remains difficult to confirm if these incidents actually occurred since no documentation or details of the deaths have been uncovered so far. Nevertheless, flower urchins are still considered highly dangerous. The severe debilitating pain of the flower urchin sting compounded by muscular paralysis, breathing problems, numbness, and disorientation can result in accidental drowning among divers and swimmers. The flower urchin was named the "most dangerous sea urchin" in the 2014 Guinness World Records. Edibility Despite being venomous, flower urchins are sometimes harvested in East Asia, Southeast Asia, and the Pacific Islands for their edible gonads. In the Sulu Archipelago of the Philippines and eastern Sabah, Malaysia, flower urchins are among the species of edible