One of the more interesting aspects for tropical forests are fish that function as seed dispersers. In Costa Rica the machacas (pictured, ~35-50 cm long) have excellent eyesight above the water and a quite a number will race out from under the over hanging tree crowns to snag a chunk of banana or a fig much to the delight of each year's class of students. In the Amazon other members of the same family, the characins (tetras, piranha), have proven to be excellent dispersers, especially in flooded forests, because fruiting trees are an island of resource, a patch of food, so foragers must move from place to place to find the patches. Fruit-eating fish in that ecosystem can move seed up to 5.5 km, dispersal on a par with large birds and mammals. However, over fishing could have an impact on tree reproduction, an excellent example of interconnections not at first evident.