Venom e behind the extended
tube feet. At least two
active compounds which are
toxic to humans have been purified from the pedicellarial venom of flower urchins in two studies. The first was discovered in 1991 and named
Contractin A. It was found to interfere with the transmission of signals at
nerve endings as well as cause
hemagglutination (clumping of the
red blood cells). When administered to
guinea pigs, it resulted in contractions in the
smooth muscles. The second, discovered in 1994, is a
protein toxin named
peditoxin. It is composed of the protein pedin and the active
prosthetic group pedoxin. At low doses to mice, pedoxin was found to result in markedly lower body temperatures,
muscle relaxation,
sedation, and
anesthetic coma. At higher doses it resulted in
convulsions and death. Pedin itself is non-toxic, but it magnifies the effects of pedoxin. When combined into the
holoprotein peditoxin, even low doses resulted in
anaphylaxis-like
shock and death. UT841, a possible third toxin isolated in 2001, has been shown to affect
brain metabolism in chicks. However, the authors are unclear on whether UT841 may actually 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 are 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.
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 , with some of the
tube feet extending past the
pedicellariae 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 sea urchins used by the
Sama-Bajau and
Tausug people to make a traditional delicacy known as
oko-oko or
ketupat tehe tehe. This is prepared by degutting the test and then filling it with
glutinous rice and
coconut milk before boiling. A follow-up study by Japanese researchers in 2001 confirmed that the
viscera of flower urchins could indeed attract crown-of-thorns starfish in both aquarium and open sea experiments. The attractant compounds were isolated and identified as
arachidonic acid and
α-linolenic acid. The authors believe that this discovery may be used to augment population control measures of the crown-of-thorns starfish, which are highly destructive to coral reefs. == References ==