Pond Boss Forums STOCKING A NEW POND Types of fish to choose Why completely different species look alike.

After reading the post about Barramundi looking like LMB, some thoughts came to me on a topic that I keep thinking about and was simply explained to me in 7th grade biology, and it's the concept of evolution and how it can create species that appear similar but are found in different bodies of water. The LMB fills in a very specific part of the food chain, and in other bodies of water this area of the food chain exist as well. For instance, look at the similarities of these freshwater and saltwater species:

LMB -> Snook
Striped Bass -> Tarpon
Catfish -> Sharks
Musky -> Barracuda
Panfish -> Pinfish/Porgies

This isn't a coincidence, each of these species is adapted for a certain spot in the food chain, and thus have similar adaptations for what they eat. For instance, Largemouth bass and Snook both have relatively large mouths and streamlined designs, which helps them to catch and eat the prey they have adapted to pursue most efficiently, in this case small baitfish(shad,shiners,mullet,herring) and crustaceans (shrimp,crabs,crawfish). The same can be said for stripers and tarpon, they are large schooling fish that are adapted to pursue large pelagic bait,i.e. mullet, herring, gizzard shad.

So now you know why when you see a musky and barracuda next to each other why they look just alike despite not being even slightly related.

What you are describing is called convergent evolution, which occurs when two distantly related and phenotypically different species evolve to converge on a similar phenotype due to similar environmental pressures (e.g. opposums and rats). The more common occurrence is when a single species splits into two populations long enough to be unable to cross breed, often due to geographic separation, but retains many phenotypic similarities. One would need to look at the evolutionary tree for the specific fish species that you mention to determine if convergent or divergent evolution applies in each case. The determiner is if the common ancestor shares the trait that is similar in the contemporary species.

Phenotypic adaptation is the process that leads to similar traits In different species through long term adaptation to environmental conditions.

A phenotype (from Greek phainein, meaning "to show", and typos, meaning "type") is the composite of an organism's observable characteristics or traits, such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior (such as a bird's nest). A phenotype results from the expression of an organism's genetic code, its genotype, as well as the influence of environmental factors and the interactions between the two. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic.