The surface fish is the top predator of the Northern Swordtail.  The swordtail use thier size and tail to attract females for mating, but the mexican tetra also use these visuals to find them.  The swordtails have developed a method of attracting a female but at the costs of these traits.  The male swordtail have evolved UV patterns that females are attracted to, but the tetra has difficulty seeing these patterns.  This trait is most prevelent in areas where the tetra and the swordtail live together (Cummings et al. 2003)  Here is a master at tricking its prey!!

Predators are not the only thing the mexican tetra needs to survive against.  They can become infected by many of the same diseases that other freshwater fish succumb to.  The main groups are; protozoans, trematodes, nematodes, and crustaceans (Rogers 1978).  The largest group that infects many different species of fish are the protozoans.  The most common disease caused by a protozoan is Ichthyophthirius, more commonly known as Ich.  Ich infects the gills and the scale of fish.  Ich tomites burrow into the fishes gills and epidermis.  This causes irritation, along with excess mucus and hyperplasia (Rogers 1978). Hyperplasia is the abonormal cell growth (Britannica 2013).  Here is one parasite worth looking at!!

Carnat JoelThe mexican plays a larger role with people.  In recent years it has become a popular fish in home aquariums, but this just a small part for what they are used for.  A. mexicanus has been used extensively by scientists to study convergent evolution.  Typically convergent evolution occurs when two different species evolve similar physical traits (Bradic et al. 2012). An example would be the relationship of birds and bats; both have wings and can fly but are not related to each other.  The mexican tetra is a unique case.  All if the different populations of the cavefish evolved isolated from each other, yet they still ended up with similar traits.  Due to the isolation of the caves, there was no genetic drift or mixing of new genes in the populations.  The different populations came from 2 distinct lineages of surface fish (Bradic et al. 2012).  Rarely is there a same species that has evolved independently from each with same ancestor still present.  This allows for the ancestral genes of the surface fish and the "newer" cavefish to be examined.

Many of the of the traits that are exhibited by these blind fish may have a beneficial use for use in people.  The cavefish have exhibited a different sleeping pattern than those of the surface fish.  The cavefish shows a sleep pattern of requiring fewer hours of sleep, this may be due to the environment change where food is in limited supply,  The activity of sleep may allow their next meal to flow by (Duboue et al. 2011).  This could be deterimental, due to when the next meal will be is unknown.  By using information gathered by studies, such as sleep patterns, it can give insight on the genetic and evolutionary traits for sleep and use them to help treat sleep problems in people.  See how other species are helping man kind!!!

Previous page                                             Home                                                                       Next page