POISONOUS FISH
By PROFESSOR C. M. YONGE
IN the multiplicity of weapons and devices for attack and defence Nature long anticipated the ingenuity of man. Only in his use of explosives and of fire has man shown originality ; but then animals do not work at a distance or indiscriminately. No device is more widespread or more potent than the use of poison, whether by way of the fangs of snakes, the jaws of insects, spiders or centipedes, the tail of scorpions or the sting of wasps, the tentacles of jellyfish or even the bite of certain snails of tropical seas. Little known, but as elaborate and effective as any of these, are the poison organs of fish, a group of animals which in their use of protective colouration, of luminous organs, even of electric organs, display a unique range of defensive and offensive mechanisms.
Popular ignorance concerning the poison apparatus of fish is due partly to a general lack of knowledge about the inhabitants of a medium alien to all but the minority who make their living by fishing, but partly to the dead hand of authority. The undoubted poisonous effects of the spines of certain fishes have been attributed to infection from the body mucus following the frequently deep and jagged wounds inflicted. The presence of an actual poison was denied by the renaissance naturalist, Aldrovandus, the great Cuvier, the Cornish ichthyologist, Jonathan Couch, and, more recently, by Sir Ray Lankester.
Gradually the barriers of medium and of authority have been overcome and the truth about the venomous powers of fish revealed. In this country the work of Dr. H. Muir Evans stands alone. In his recently published Sting-fish and Seafarer* he has had the happy idea of re-telling the story of his investigations into the poison apparatus of fish against the background of his own growth of know- ledge and love of the sea and of the fish that live within it. When a ship's surgeon he made early acquaintance with poisonous fish on the reefs of Mauritius, but, after settling down in practice at Lowes- toft, he had more direct and tragic experience of their powers when a young fisherman he was treating died after being stung by a Weaver. This it was, he tells us, that led him to commence work on stinging fish.
Studies of the poison spines of the Lesser and Greater Weaver, the most dangerous of British stinging fish, which possess poison glands associated with spines along the back and on the gill covers, led to the demonstration of similar glands at the base of the stout spurs in front of each of the dorsal fins of the common Spurdog or Spiny Dogfish and of the Port Jackson Shark of the Pacific. The Sting Ray, one species of which occurs in British seas, but all too many of which lurk on the sandy bottom of tropical lagoons or in
*-Faber and Faber, x53. the shallows between coral heads on the surface of reefs, has a weapon of a different type. Along the side of the long whip-like tail lies a serrated spine, employed with deadly effect when the tail is lashed sideways. Here the poison gland runs along grooves on the under surface of the spine, so that its contents are automatically conveyed into the wound.
At Madeira acquaintance was made with the Black Scabbard Fish, caught at such depths that the expanding gases of the swim bladder force out the stomach and intestines when it is brought to the surface, and with a dagger-like spine behind the vent which, judging from the effect of wounds inflicted on fishermen, has probably an associated poison gland. This fish is also said to have venomous teeth and saliva that prevents the clotting of blood and so closure of the wound. Visitors, in happier days, to the aquarium of the Stazione Zoologica at Naples may retain memories of the Roman Eels gracefully insinuating their handsome, mottled bodies through the earthenware jars and pipes without which no marine eel appears happy in captivity. They differ from our familiar Conger in the relatively stouter body, and sharper, more vicious, head. Their relatives, the Moray Eels, are abundant in the crevices of tropical coral reefs. In all the instant reaction to an intruder is attack with formidably armed jaws. The effects of the bite are so serious as to indicate poison, a fact well known to the Romans, but the actual presence of poison-glands still remains a matter of uncertainty. The blood of eels has 'a haemolytic action, dissolving the red blood corpuscles, so that, as Dr. Muir Evans notes, contamination of the wound with the blood of the eel would have the effect of poison.
Poisonous Catfishes from America, archaic Chimaeras from deep waters, tropical Surgeon-Fishes and Trigger-Fishes, are amongst other creatures studied by Dr. Muir Evans, but probably the most terrifying of all are included amongst the Scorpion-Fishes of the tropical Indo-Pacific. These he encountered at Mauritius, but they are equally known and feared in the East Indies, in Tahiti and on the reefs of the Great Barrier fringing the coast of Queensland. There they are known as Stonefish, and dreaded no less than sharks. They lie concealed from their prey by the resemblance of their blotched bodies covered with tubercles and warts to the multi- coloured coral rocks amongst which they live. Along the back of the body lie a series of 53 spines, each with an associated poison- , gland. Normally covered with skin, these spines are erected and bared on pressure from above, so that a naked or inadequately shod foot receives a multiple dose of one of the most powerful of nerve poisons. The pain is overwhelming—sufferers have even been known to amputate the injured part—and of long duration, and many cases of death have been reported. It will probably interest Dr. Muir Evans to know that amongst the aboriginal tribes in the coastal regions of North Queensland the youths are warned against the effects of the Stonefish in their initiation ceremonies. A model is made in bees- wax and concealed within the clearing used for the ceremonies. After much thrusting of spears, to indicate fishing, one of the older men steps on the model and falls shrieking to the ground writhing in simulated agony.
In these days danger from poisonous fishes assumes a wider significance, with men of many temperate countries fighting over vast stretches of tropical seas. Initiation takes the more modern
form of scientific pamphlets, such as one recently, received from Australia on Poisonous and Harmful Fishes by G. P. Whitley
of the Australian Museum, Sydney. Published for the especial benefit of the Allied Forces in the South West Pacific, this deals not only with dangers from poisonous Sting Rays, Catfishes, Stonefish and the like, and with predacious sharks and gropers, but also with those tropical fish which are poisonous to eat (which the stinging fish arc not). The latter include the well-known Toadoes or Puffer-fishes, the eating of which' almost cost Captain Cook his life in 1774, Porcupine-fishes, Trigger Fish, a fish resembling the Red Bass, which poisoned members of the expedition led by Quiroz to the Solomons in i6o6, Chinaman Fish and a variety of others. Many of these are little known, but war, which stimulates activities ranging from radio-location to the mass destruction of rats, may also have the incidental effect of promoting the study of tropical fishes.
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