![]() ![]() The nematodes and the arthropods belong to a clade with a common ancestor, called Ecdysozoa. Finally, the arthropods, one of the most successful taxonomic groups on the planet, are coelomate organisms with a hard exoskeleton and jointed appendages. The nematodes, or roundworms, possess a pseudocoelom and consist of both free-living and parasitic forms. The flatworms are acoelomate organisms that include free-living and parasitic forms. Associated with bilateralism is the beginning of cephalization, the evolution of a concentration of nervous tissues and sensory organs in the head of the organism, which is where the organism first encounters its environment. These phyla are also bilaterally symmetrical, meaning that a longitudinal section will divide them into right and left sides that are mirror images of each other. The animal phyla of this and subsequent modules are triploblastic and have an embryonic mesoderm sandwiched between the ectoderm and endoderm. ![]() Compare the internal systems and the appendage specialization of arthropods.Describe the structural organization of nematodes.Describe the structure and systems of flatworms. ![]() Use magnification lens to observeLearning Objectives By the end of this section, you will be able to: Similar to ick, but telltale sign is movement and possibly eyespots, something that is not found in ick. Note: Pale fish with drooping fins, rapid respiration and/or hollow bellies indicate more extensive infestation. Secondary infections are also common and can be treated with antibiotics or general cures like Lifeguard® or Fungus Guard®. Remove activated carbon and repeat after 48 hours conduct a partial water change between treatments. Tetra Parasite Guard® with praziquantel is effective but must be carefully administered per directions. Avoiding stressful conditions is a key to prevention, but once an outbreak occurs, prompt treatment is critical. Flukes are often present in aquariums but remain harmless under ideal conditions. Undesirable environmental conditions-including poor water quality, overcrowding and/or stress by incompatible species-creates conditions that can lead to destructive outbreaks. Scratching against objects by the affected fish ![]()
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