Moray eels (Figure 15-16) are a potential hazard on tropical reefs, and a few species occur in the warmer temperate regions of California and Europe. They are secretive animals, with a body-form that is highly specialized for life within reef crevices, and only occasionally are they exposed on the reef top. Although relatively few grow large enough to seriously threaten divers, these may be over 6 feet long, and their powerful jaws, with long needlelike teeth, can grievously wound humans. Divers that have been injured by morays usually have reached into a reef crevice for some object and been struck by an unseen moray that probably felt threatened, or possibly mistook the hand for prey. Generally in this situation the moray will release its hold upon recognizing that it has taken hold of something unfamiliar, and if the diver can resist his natural impulse to pull free he may escape with no more than a series of puncture wounds. But such presence of mind in this situation is rare, and the diver often receives severe lacerations when he wrenches his hand from between the backward-projecting teeth of the eel. 15.3.3 Barracudas Barracuda (Figure 15-17) that grow to more than about 4 feet long are potential hazards. These animals can severely injure divers. Fortunately, there have been relatively few attacks by barracuda on humans. Large barracuda often follow divers about, as if expressing interest, but probably there is no danger in this interest. In these situations the barracuda has had a good look at the divers, and even the smallest diver is much larger than anything the barracuda is apt to eat. Barracuda have large canine teeth adapted for seizing the fishes that are their prey. These teeth however are ill-suited to tear pieces from a large animal like man. Attacks on divers are most likely to occur where the barracuda has not had a good look at its victim. Where visibility is limited, for example, the barracuda may see only a moving hand or foot, which may appear as prey in the murk. An attack may also Occur when a diver jumps into the water, as when entering from a boat. To a nearby barracuda the diver's splash may simulate the splash of an animal in difficulty- hence vulnerable- and the barracuda may strike without realizing what is there. Thus one should be especially alert in murky water, and avoid unnecessary splashing when large barracudas may be present. 15.3.4 Other Fishes That Bite Any large fish with sharp teeth or powerful jaws can inflict a damaging bite. Generally however such fish are hazardous to divers only when handled. The pufferfishes and triggerfishes can be especially troublesome in this respect. These fishes have teeth and jaws adapted to feeding on heavily armored prey, and large individuals are quite capable of biting off a human finger. In the tropics, some of the larger sea basses can grow to over 7 feet long. These giant beasts are potential hazards. Their mouths can engulf a diver, and there are reports of them having done so. 15.3.5 Seals and Sea Lions Juvenile and female seals and sea lions frequently frolic in the water around divers. Underwater encounters with sea lions can be expected if the animals are anywhere around during a dive. Their activity can be distracting or even frightening, but rarely holds any danger. Large bull seals and sea lions, although aggressive on the above-water rocks of their breeding rookery, apparently do not constitute a serious threat under water. 15.3.6 Whales Common sense should tell divers to avoid large whales under water. Usually whales stay clear of divers, so that most incidents occur when a diver puts himself in jeopardy by provoking the whale. Whales may be startled when a diver approaches too close, and strike the diver senseless in their sudden surge of evasive action. Such a blow can be damaging out of water; under water it can be tragic. Killer whales have a bad reputation, mostly because they feed aggressively on other marine mammals, including seals, sea lions and porpoises, with which human observers often are emotionally attached. The evidence indicates, however, that their reputation as a major threat to divers is overstated. Nevertheless, they have the potential for grievous assault on divers owing to their large size and predatory habits, and this potential dictates caution. 15.4 MARINE ANIMALS THAT SHOCK Among marine animals that produce an electric shock, the only one significantly hazardous to divers are the electric rays which have representatives in all the oceans of the world. The torpedo ray of California (Figure 15-18) is an example. Electric rays are slow-moving animals and alert divers should have little trouble steering clear of them. As is true of so many undersea hazards, divers threatened by these animals are mostly those that have molested them. The shock, which can be as much as 200 volts in large rays, is generated by modified muscles in the forward part of the animals disc-shaped body. It is enough to severely jolt a diver. |