Anatomy of finfish and shellfish

Unit 3 - Oral region and Associated structures

3.1. Adaptations for feeding
(The feeding habits or feeding behavior of fishes is the search for and ingesting of food) The diversity in feeding habits that fishes exhibit is the result of evaluation leading to structural adaptation for getting food from the environments. The structural adaptation of feeding organs such as 1) position and shape of the mouth 2) Presence or absence of “Teeth”. 3) Gap of the mouth etc., greatly help in predicting the nature of food and mode of feeding of the fish (in question).
Section 1: Major feeding types :
On the basis, fishes can be classified, according to their feeding habits as 1) Predators 2) Grazers 3) Food strainers 4) Food suckers and 5) Parasites.
1) Predators
Fishes that feed on macroscopic animals, they usually have well developed grasping and holding teeth as in many sharks (Elasmobrabch) the Barracuds (Sphyraena), the pikes (Esox) gars (Lepisosteus).
2) Grazers
In Grazing, the food is taken by bites or continual browsing (Grazing characterize many fishes that feed on planktons or on bottom organisms) (sometimes organisms are taken single or at other times in small groups) may feed on bottom or column – a bluegill (Lepomis macrochirus), Parrot fishes (scaridae) Butterfly fishes (chaetodontidae) browsing on coral reef.
3) Strainers (Filter feeders)
Filter the water for plankton, here foods are selected by size and not by kind. Herring clupidae, Gizard, shads (Dorosoma), Paddle fish (polyodon) whale shark (Rhincodon) also have efficient food straining or filtering adaptation. The principal adaptation for filter feeding or strainers is the developemt of numerous, closely – set and elongated gill rackers.
4) Suckers
The sucking into the mouth of food or food containing material is taken practiced by bottom feeding fishes such as the sturgeons (Acipenseridae) and suckers (catostomidae)
5) Parasites
Parasitisum is perhaps the most unusual and highly evolved feeding habits among animals. They suck body fluid after rasping a hole in the sides of the body. Parasitic lampreys (Petromyzonidae), Sea lamprays (Petromyzon marinus) Pacific lampreys (Lamptra tridentata)