rebg38
07-28-2008, 05:05 PM
Lepomis microlophus (Redear Sunfish)
Tid-bits
1.The redear is the first-known species of " Centrarchidae " based on fossil records, as old as 16.3 million years.
2. The redears most distinct characteristic is the red edge on the opercle ("ear") flap of the male (orange on the female). The opercle is never greatly elongated.
3. Its gill cover flap is semi-flexible and can be bent at least to right angles.
4. Its pectoral fins are long and more pointed that those of other panfish.
5. Redear are "molluscivorous". Its favorite food is Snails.
6. Redear are primarily bottom feeders, meandering along the lakebed feeding on snails and other shelled creatures.
7. Redear are generally "light" biters (which leads us into the next topic), suction feeding;
Suction Feeding
Like all others of the Sunfish Family, redear are suction feeders, which involves quickly opening the jaws to create negative pressure inside the mouth cavity (buccal cavity). The resulting inrushing water then carries suspended food items (large or small) with it. Most advanced teleosts; fishes with bony skeletons, (for example bass) use this method. In these fishes the jaws are shortened and the front portion of the upper jaw (the premaxillary bone) is "postusile", meaning it can be pushed forward by the toothless maxillary bone behind it. This mechanism allows for a quick and wide gape and consequent sucking in of water together with any suspended food.
Most advanced teleosts also have "pharyngeal teeth" attached to the fifth gill arch that help in processing the food obtained by suction feeding.
Suction feeding is also ideal for trapping food in the gill area as the sucked-in water is expelled through the gill covers. Therefore, many gill raker specializations can be found among advanced teleosts such as the sunfish family. The largemouth bass, for example, has short, widely spaced and pointed gill rakers that can hold on to any fish sucked in and also help in rubbing off its scales before swallowing. The longest and finest gill rakers are possessed by the plankton-feeding crappies. Redear sunfish have the shortest and stubbiests gill rakers adapted to their snail-eating habits (which leads us into the next topic, Pharyngeal Jaws). No one method is generally used exclusively, and feeding often involves a mixture of all three methods.
Pharyngeal Jaw Apparatus (PJA)
The redear's Pharyngeal Jaw Apparatus (PJA) has thick pharyngeal teeth, hard, movable plates in its throat, which allow it to crush the shells of little snails, small mussels, and small clams. They are able to spit out the shells (small fraguements are ejected out through the gills, larger fraguments out the mouth), retaining only the flesh of the shellfish. Although they are primarily molluscivorous, they also feed on nymphs and other aquative insects, but their pharyngeal crusing ability has compromised their suction performance, compared to other sunfish.
Tid-bits
1.The redear is the first-known species of " Centrarchidae " based on fossil records, as old as 16.3 million years.
2. The redears most distinct characteristic is the red edge on the opercle ("ear") flap of the male (orange on the female). The opercle is never greatly elongated.
3. Its gill cover flap is semi-flexible and can be bent at least to right angles.
4. Its pectoral fins are long and more pointed that those of other panfish.
5. Redear are "molluscivorous". Its favorite food is Snails.
6. Redear are primarily bottom feeders, meandering along the lakebed feeding on snails and other shelled creatures.
7. Redear are generally "light" biters (which leads us into the next topic), suction feeding;
Suction Feeding
Like all others of the Sunfish Family, redear are suction feeders, which involves quickly opening the jaws to create negative pressure inside the mouth cavity (buccal cavity). The resulting inrushing water then carries suspended food items (large or small) with it. Most advanced teleosts; fishes with bony skeletons, (for example bass) use this method. In these fishes the jaws are shortened and the front portion of the upper jaw (the premaxillary bone) is "postusile", meaning it can be pushed forward by the toothless maxillary bone behind it. This mechanism allows for a quick and wide gape and consequent sucking in of water together with any suspended food.
Most advanced teleosts also have "pharyngeal teeth" attached to the fifth gill arch that help in processing the food obtained by suction feeding.
Suction feeding is also ideal for trapping food in the gill area as the sucked-in water is expelled through the gill covers. Therefore, many gill raker specializations can be found among advanced teleosts such as the sunfish family. The largemouth bass, for example, has short, widely spaced and pointed gill rakers that can hold on to any fish sucked in and also help in rubbing off its scales before swallowing. The longest and finest gill rakers are possessed by the plankton-feeding crappies. Redear sunfish have the shortest and stubbiests gill rakers adapted to their snail-eating habits (which leads us into the next topic, Pharyngeal Jaws). No one method is generally used exclusively, and feeding often involves a mixture of all three methods.
Pharyngeal Jaw Apparatus (PJA)
The redear's Pharyngeal Jaw Apparatus (PJA) has thick pharyngeal teeth, hard, movable plates in its throat, which allow it to crush the shells of little snails, small mussels, and small clams. They are able to spit out the shells (small fraguements are ejected out through the gills, larger fraguments out the mouth), retaining only the flesh of the shellfish. Although they are primarily molluscivorous, they also feed on nymphs and other aquative insects, but their pharyngeal crusing ability has compromised their suction performance, compared to other sunfish.