What is a Fish?
Definition: an animal that has, for at least a stage of it's life, a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; a tail that extends beyond the anus
Definition: an animal that has, for at least a stage of it's life, a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; a tail that extends beyond the anus
Body Plan:
The evolution of jaws and the evolution of paired fins were important developments during the rise of fishes. Feeding: There are herbivores, carnivores, parasites, filter feeders, and detritus feeders. Circulation: They have a closed circulatory system. Respiration: Breathe through gills that are made up of feathery, threadlike structures called filaments. Some fishes have several gill openings, others have single openings. |
Excretion:
Most fishes rid themselves of nitrogenous wastes in the form of ammonia. Some wastes diffuse through the gills into the surrounding water. Others are removed by kidneys, which are excretory organs that filter wastes from the blood. Response: They have well-developed nervous systems organized around the brain. Also have highly developed sense organs. Reproduction: The eggs of fishes are fertilized either externally or internally. |