Nutrition

As in stony and soft corals, the role of zooxanthellae in zoanthid nutrition has created some debate, not only amongst scientists but also amongst aquarists. Zoanthids can obtain nutrition in a variety ways: via the translocation of nutrients from zooxanthellae, from the capture of zooplankton, from the capture of detritus and by direct uptake of dissolved nutrients in sea water.

Zooxanthellae have long been known as providers of nutrition to their coral partners, about this there is no debate. However, the degree to which they provide nutrition is not completely knowrn. Numerous studies have shown that the degree to which zooxanthellae contribute nutrition varies from genera to genera, and perhaps even from species to species. Zoanthids spp. are generally considered to derive the greatest amount of nutrition from their zooxanthellae. Steen and Muscatine (1984) found that Zoanthids sociatus could obtain up to 48% of its required carbon from its zooxanthellae, in what they admit may be an underestimate. Researchers have never observed Zoanthus spp. to feed in the wild but they have been able to illicit feeding responses to dead organic materials and amino acids such as proline and glycine (Reimer 1971; Sebens, 1977; Trench, 1974). Trench (1974) found that the internal mesenteries contained numerous cells and nematocysts that would presumably aid in digestion. Sebens (1977) showed through coelenteron content analysis that Zoanthus sociatus contained numerous crustacean fragments and detritus, and that numbers were higher at night. However, of 910 polyps studied during the day only 31 contained food items; the number increased very little at night.

Amongst Protopalythoa and Palythoa, zooxanthellae contribute a smaller portion to the energy budget and feeding takes on a more important role (Steen and Muscatine, 1984). Studies have shown that zoanthids from these genera actively display feeding behaviour and are capable of ingesting whole zooplanktoners such as amphipods and copepods Reimer, 1971; Sebens, 1977). Azooxan-thellate genera such as Epizoanthus and Parazoanthus obviously rely greatly on feeding to obtain sufficient nutrition.

The role that uptake of exogenous compounds plays in zoanthid nutrition is not fully understood. Reimer (1971) and Trench (1974) have both shown that Zoanthus spp. can actively uptake sugars

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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