NAUI Master Scuba Diver 56 The Diving Environment The third group of Cnidarians that cause trouble for the unprepared diver are the Anthozoans, which include the stony corals, gorgonians, and sea anemones. In general, this is a colorful and harmless group of animals with a few exceptions. Every diver should know that he or she may be cut by shallow water corals like elkhorn (Acropora palmata) or staghorn (Acropora cervicornis) coral. If you do receive a coral cut, wash it with warm soapy water and apply some antiseptic cream to the area. Most people consider shellfish as something to eat (clams, oysters, scallops, etc.) or something to collect, but few realize that there are venomous mollusks. The phylum Mollusca contains a genus of gastropod known as Conus which contains a venom sac and a small poisonous dart capable of penetrating an ungloved human hand. These creatures feed on other gastropod mollusks, polychaete worms, and fish. Consequently, they have developed a highly effective venom apparatus. If stung, the victim usually experiences immediate intense pain or a sharp stinging sensation, followed by a burning, then a numbness around the wound site. This may spread eventually over the entire body, producing a muscle paralysis. CPR, a respirator, and the treatment for primary shock are usually effective treatments. This envenomation is easily avoided by picking up any unknown shellfish with wet suit gloves, or more simply by avoiding handling these creatures completely. Another mollusc that is known to have killed humans through envenomation is the blue-ringed octopus (Octopus maculosus). This species contains tetrodotoxin in its salivary glands which it probably acquires through its prey. The symptoms following the bite of this octopus are similar to eating fugu, since this is a potent neurotoxin. In general, all the members of the octopus family (Cehpalopoda) are shy and not inclined to bite. The only time people have been bitten by these gentle creatures is when they handle them. Look, take pictures, but do not touch. The last invertebrate group of animals to consider are the echinoderms (Phylum-Echinodermata), which includes seastars, sea urchins, and sea cucumbers (figure 2-25). These are a group of exclusively marine bottom-dwellers FIGURE 2-25. SEA URCHINS with external skeletons, protruding spines, radial symmetry, and a gut with two openings. Sea urchins have spines, some of which are hollow and brittle. They can penetrate the skin, break off, and become irritating. Crushing the spines in the body tissue may fragment them and lead to the eventual absorption process with some fine-spined species. This practice should be avoided with thick-spined urchins. Some spines may have to be removed surgically. Learn the best treatment for each type in each new area. Always keep the wound area clean to prevent wound infection. Some sea urchins have a special venom apparatus called pedicellaria which can inject a venom causing some pain, swelling, and joint stiffening. It is best to avoid handling sea urchins, but if you do, always wear gloves. One species of starfish, the Crown of Thorns (Acanthaster planci), also has stout poisonous spines. Wounds from these spines are extremely painful, but this Pacific species is the only poisonous seastar. There are many venomous fish, such as stingrays (figure 2-29), lionfish (figure 2-26), and stonefish (figure 2-27), and all have some general characteristics in common. First, as soon as the spines from these animals enter the skin, there is an immediate intense pain that may become excruciating over the next hour. The pain may persist for six to ten hours before diminishing. There will be swelling (edema) and “redness” around the injury
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