This set of materials is about gulf sturgeon. The reading passage describes three plausible theories about the cause of jumping of this ancient fresh water fish, while the lecturer points out that none of the theories is credible for several reasons.
To begin with, the lecturer states that feeding habit of this fish is different from the reading passage’s claim. Gulf sturgeon eats only organisms on the floor such as crustaceans. Moreover, they come to Florida just to spawn their eggs rather than feed themselves.
These counter reading passage’s claim that gulf sturgeon jumps out of the water in order to catch prey flying insects.
In addition, the lecturer points out that gulf sturgeon doesn’t have large external parasites like sucker fish, the only kind of sturgeon that has parasites on its skin is a farm sturgeon and this fish doesn’t jump to remove the parasites on its skin.
This casts doubt on reading passage’s claim that gulf sturgeon jumps out of the water as a means of removing parasites on its skin.
Finally, the lecturer argues that jump of gulf sturgeon might be mistaken as a response to invaders of its territory such as boat, while it jumps anyway regardless of boat’s presence.
This casts doubt on reading passage’s argument that gulf sturgeon jumps out to protect their territory form invaders.