Threespine sticklebacks that invaded freshwater lakes have lost their pelvic spines. What other adaptations might you expect to see in fish that have moved from a marine environment to a freshwater habitat?
Threespine sticklebacks that invaded freshwater lakes have lost their pelvic spines. What other adaptations might you expect to see in fish that have moved from a marine environment to a freshwater habitat?
Threespine sticklebacks (Gasterosteus aculeatus) are commonly found in the ocean. They are carnivorous, which usually feed on insects, crustaceans, and larvae.
Marine sticklebacks are characterized by the presence of spines in their dorsal fins and paired pelvic spines on the underside of the fish. They have no scales. The pelvic spines provide defense against some vertebrate predators. The absence of pelvic spines in freshwater sticklebacks indicates the low predation pressure.
Sticklebacks of these two ecotypes show predictable differences in foraging and reproductive behavior that are associated with the habitats in which they live.
marine sticklebacks are generally larger and have streamlined body shapes, whereas freshwater sticklebacks are smaller, deeper-bodied
Marine sticklebacks typically show full armor, and most freshwater populations show reduced numbers of lateral plates.
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