Amphiprion ephippium-Red saddleback anemonefish

The red saddleback anemonefish, Amphiprion ephippium, also known as the saddle anemonefish, is a clownfish that lives in the Indo-Pacific area. They are considered small even for a clownfish, but are very aggressive toward other animals, especially to other types of clownfish.

They can grow up to be an average maximum of 5 inches. The minimum aquarium tank capacity is 30 gallons, and they should be fed chopped shrimp and frozen herbivore preparations.

Found in the genus Amphiprion, they are most closely related to organisms in the genus Abudefduf, within the family Pomacentridae. Within the sub-order Labroidae, identified by their possession of a specialized Pharyngeal Jaw apparatus, they are more closely related to families Embiotocidae and Cichlidae than Labridae.

Example of an analogous structure:

The Pharyngeal Jaw is found in generalized percomorph fish. The upper and lower "pharyngeal jaw" are found within the throat of the fish, and transport food into the oesophagus, while the oral jaws collect and crush the food. the families of Pomacentridae, Embiotocidae, Cichlidae and Labridae, however, possess a modified form of the pharyngeal jaw, know as the Pharyngeal Jaw Apparatus (PJA), that took on the task of crushing the food from the oral jaws, allowing them to diversify into different food collecting modes. This resulted in the four families to be placed together in the sub-order Labroidei, due to the uniqueness of the structure. However, due to recent comparisons of 78 whole mitochondrial genome sequences from a variety of perciforms and other species with similar characteristics, (the group known as Percomorpha), it was found that organisms in the family Labridae did not share a common ancestor that possessed the PJA with the other three families, including Pomacentridae. The PJA, therefore, must have evolved twice independently in the history of Percomorpha. Since the PJA performs similar functions and has a similar structure in family Labridae and Pomacentridae (and, by extension, organisms in family Pomacentridae, i.e. Red Saddleback Anemonefish) this is a prime example of an analogous structure.

Example of a homologous structure:

It is commonly thought by biologists that the similarities between the underlying structure of bird wings and fish fins are homologous. The internal structure of bird wings and fish fins are very similar, though these appendages are used for different purposes. The red Saddleback Anemonefish's pectoral fins are stretches of webbing between long spines, which attach to pectoral muscles and are used to stop and control the fish's movement well when swimming. The spines are like the central lines of a feather, for example, like those found in the wing of a field sparrow, Spizella pusilla.
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