have colonies of up 12,000 polyps per m . Admittedly this was a unusually high density and was attributed to the higher nutrient and detrital levels in the bay at the time of the study. Very little is j J j known about the growth rates and polyp densities of the other genera of zoanthids kept in aquaria such as Acrozoanthus, Para-zoanthus and Epizoanthus; an area where hobbyists could certainly make a contribution. The rapid growth rates of Zoanthus, Palythoa and Protopalythoa should be taken into consideration wiien placing new colonies and when planning the aquascaping of the aquarium.

Defense Mechanisms

As we discussed in chapter one, soft corals possess numerous chemicals used for aggressive behaviour against other corals and to deter prédation. Zoanthids are similar in that they too possess a host of organic chemicals and physical characteristics used for the same reasons.

Chemical Defenses

It has long been know that zoanthids such as Zoanthus and Palythoa contain toxic chemicals. Most thoroughly studied of these v e *

has been palytoxin, (PTX), considered one of the most poisonous marine toxins known to date (Mereish et al., 1991). Palytoxin acts by changing the electrical properties of the Na-K pump and causes depolarization in heart, skeletal and smooth muscle cells, and nerves resulting in paralysis and eventually death (Seyama, 1991). Gliebs et al. (1995) found this toxic substance in many of the Caribbean species of Zoanthus and Palythoa but the levels were highly variable and did not appear to correlate with their reproductive cycle or with the amount of zooxanthellae. However, Kimura et al. (1971) found that Palythoa tuberculosa in Okinawa possessed high levels of palytoxin during the breeding season, with the majority of the toxin concentrated in the eggs; levels reaching 100,000 MU/g, far exceeding the levels of toxin found in puffer roe. The Hawaiian zoanthid, Palythoa toxica contains an especially toxic chemical (most likely palytoxin) within its gastric cavity. Bowers and Walsh (1971) reported that a student collector-had to be hospitalized for several days after accidentally touching a colony to an open wound on his hand. It may be that these were gravid polyps and the toxin was concentrated in the gastrovascular cavity clue to the presence of eggs. The early Hawaiians were

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The COMPLETE guide to Aquariums

The COMPLETE guide to Aquariums

The word aquarium originates from the ancient Latin language, aqua meaning water and the suffix rium meaning place or building. Aquariums are beautiful and look good anywhere! Home aquariums are becoming more and more popular, it is a hobby that many people are flocking too and fish shops are on the rise. Fish are generally easy to keep although do they need quite a bit of attention. Puppies and kittens were the typical pet but now fish are becoming more and more frequent in house holds. In recent years fish shops have noticed a great increase in the rise of people wanting to purchase aquariums and fish, the boom has been great for local shops as the fish industry hasnt been such a great industry before now.

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