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Two Stonefishes occur in Queensland waters: the Reef Stonefish, Synanceia verrucosa (Bloch and Schneider), which inhabits lagoons and reef-flats of the Great Barrier Reef, and the Estuarine Stonefish Synlanceia horrida (Linnaeus), which is found in muddy bays and estuaries of the mainland to at least as far south as Moreton Bay. Both are unattractive fish; the smooth skin is covered with warts and protrusions, and may have marine encrustations (algae; hydroids; etc.) growing on it to aid in camouflage. The eyes are small, and carried on bony bosses. These are conjoint in horrida, but well separated in verrucosa.
An additional distinguishing character is that the mouth cavity is yellowish-green in horrida, but is whitish, flecked with red, in verrucosa; further more; the pectoral fin of horrida has 16 rays, and that of verrucosa has 18 or 19. Each is a sluggish swimmer and depends on camouflage to catch its prey; when lying motionless near an eroded piece of dead coral, or among weed-encrusted rubble, it is well near undetectable. Scooping movements of the great paddle-shaped pectoral fins enable the Stonefish to bury itself very rapidly below the surface of sand or sandy mud until only the eyes and the upper rim of the mouth are visible.
There are 13 strong dorsal spines, each bearing twin venom glands and discharging through ducts enclosed in grooves in the spines. The tips of the grooves have plugs of tissue which burst free only after a certain pressure has been exerted on the glands, as when the spines have driven into the sole of a foot. There is then a sudden flood of venom into the wound, rather than a progressive trickle. Pain is immediate and intense; the affected part swells considerably, respiration becomes irregular, blood-pressure falls, and partial paralysis often results, sometimes followed by death. Fortunately in recent years, an antivenin has been developed by the Commonwealth Serum Laboratories.
Immediate field first-aid includes immersion of the wound in hot water for at least 30 minutes, or until lasting relief is obtained, taking care to avoid scalding. If the patient becomes unconscious, external cardiac massage and mouth-to-mouth resuscitation may be required. Medical treatment may involve repeated infiltration of the wound with a local anaesthetic, with or without administration of the antivenin.. The largest Stonefish (S. horrida) seen to date have come from Beachmere (Moreton Bay) where they are quite common. One specimen measured 470 mm in length. These fish are capable of surviving at least 24 hours out of water.
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