Eating Across Phyla

Temporal Influences on Bluegill Nutrition

Bluegills use strong sensory structures to identify possible prey items.  These structures are discussed thoroughly in the adaptation section.  Once they have identified that an organism is edible, bluegills use gill rakers and bands of teeth to suck in their food.  During summer months, bluegills generally consume up to 35% of their body weight on a weekly basis (Spotte, 2007). On the other hand, this rate drops to 1% over winter because food sources are not readily available (Spotte, 2007).  As omnivores, bluegills consume a wide variety of both plants and animals.

Bluegills Feeding in Chilly Mississippi Water (Image taken by Author)

Nutrition of a Juvenile Bluegill

While hiding from predators in weed beds, juvenile bluegills feed on algae and zooplankton.  Eventually, they leave the weed beds to feed on a wider variety of flora and fauna.  This allows them to negate competition with other fish species that stay within the thick aquatic cover.  At maturity, bluegills consume aquatic insects, small fish (such as the common shiner), larvae, and amphibian eggs.   Still, 50% of bluegill consumption in the Mississippi River is algae (Spotte, 2007).  This vegetation may not be as nutritionally beneficial, however.  Under extreme times of stress, bluegills have been known to consume their own eggs and offspring to fulfill nutritional needs!

 

Flow of Nutrients in a Bluegill

Once ingested, nutrients follow a general path through bluegills.  Food items travel towards the stomach.  Here, the items are broken down until they travel to the intestine.  The intestine finishes breaking down nutrients into simple molecules with enzymes.  After bluegills have absorbed most all molecules that have nutritional value, waste material travels out of their anus.  The absorbed nutrients enter a closed circulatory system that contains arteries and veins.  A two-chambered heart facilitates a continuous flow of nutrient-rich blood in a single circuit to cells and tissues throughout a bluegill's body. 

 

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