52 



DANGEROUS MARINE ANIMALS 



jection on the terminal fang of the valve. A sensory bristle is 

 located on the inside of each valve. Contact with these bristles 

 causes the small muscles at the base of the valve to contract, thus 

 closing the valves and injecting the venom into the skin of the 

 victim. 



One of the primary functions of pedicellariae is that of defense. 

 When the sea urchin is at rest in calm water, the valves are gener- 

 ally extended, moving slowly about, awaiting prey. When a foreign 

 body comes in contact with them, it is immediately seized. The 

 pedicellariae do not release their hold as long as the object moves, 



T> 



VALVES OR 

 JAWS 



VALVE MUSCLES 



VENOM GLAND 



STALK 



Fig. 25. Globiferous pedicellariae from the sea urchin, Salamacis bicolor 



Agassiz. This is representative of the venomous type of pedicellariae which 



are found in other species of sea urchins. (Kreuzinger) 



and if it is too strong to be held, the pedicellariae are torn from 

 the test, or shell, but continue to bite the object. Detached pedicel- 

 lariae may remain alive for several hours after being removed 

 from the sea urchin. 



Medical Aspects. Penetration of the needle-sharp sea urchin 

 spines may produce an immediate and intense burning sensation. 

 The pain is soon followed by redness, swelling, and an aching sen- 

 sation. Numbness and muscular paralysis have been reported. 

 Secondary infections are not uncommon. 



The sting from sea urchin pedicellariae may produce an imme- 

 diate, intense, radiating pain, faintness, numbness, generalized 

 muscular paralysis, loss of speech, respiratory distress, and in 



