Invertebrates
Cnidaria
Cnidaria (formerly Coelenterata) may be stationary creatures (e.g. ‘fire coral’, Millepora alcicornis, which is associated with reefs in, for example, the Caribbean and Australia) or free swimming (e.g. jellyfish, such as the Portuguese Man-of-War or Physalia physalis). They have stinging cells or nematocysts (40 μm spheres that contain a viscous fluid composed of multiple toxins), and a long thread-like coiled tube (nema). When physical, osmotic or chemical stimuli trigger the nematocyst, its internal pressure produces an explosive inversion of the nema and the contents of the capsule are injected into the victim.
The Portuguese Man-of-War jellyfish is partic ularly dangerous and can cause death. Its nemo cysts contain a wide range of biologically active substances, including histamine, haemolytic toxins, phospholipases, proteases and a powerful neuromuscular toxin – hypnotoxin. Acute reactions involve stinging and burning, followed by the development of painful and pruritic linear papules and wheals. Acute systemic reactions to Physalia envenomation may include hypotension, shock, seizures, ataxia, haemolysis and acute renal failure. Other possibly lethal jellyfish include Stomolphus nomurai, which occurs in the waters around China. The box jellyfish Chironex fleckeri, found in the Indo-Pacific region, is reputed to be the world’s most venomous marine animal and has been responsible for at least 80 recorded deaths in Australia. The venom has a range of autonomic effects, such as vasospasms, cardiac irregularities, peripheral neuropathy, aphonia, ophthalmic abnormalities and parasympathetic dysautonomia. For purification of coelenterate venoms, capillary electrophoresis, followed by binding to high-titre commercial ovoid hyperimmune serum, is the technique of choice (Burnett et al. 1996).
