Other Techniques

Other Techniques

1. Filter Feeders
2. Suspension Feeders: Distinguished from filter feeders because they actively capture food particles from the water with tentacles
   1. Corals
      • Supplements food derived from Zooxanthellae
      • Usually at night
3. Planktivores - Eat plankton. Include fishes such as Blue Chromis, Brown Chromis, and Creole Wrasse
   1. • Physical Properties
        • tend to have small bodies that are streamlined and have forked tails to enhance propulsion
        • catching tiny fragile plankton requires small mouth without strongly developed teeth but with jaws capable of rapid and extensive protrusion to snatch the prey
        • smaller species tend to have monochromatic coloring - makes it harder for predators to see them
        • keen eyesight and binocular vision to pick out and catch plankton
      • Behavioral Properties
        • One study found that planktivores were most likely to be found on the incurrent side of the reef, where there was an input of zooplankton
        • Large species such as Whale Shark or Giant Manta swim through water column with open mouth to catch plankton. Don't need to worry about predators due to size
        • Smaller species often found in schools if feeding off reef - subject to more predation
        • some species feed off bottom of reef keep belly close to substrate
          • Yellowhead Jawfish - inhabit sandy bottoms and near holes - will retreat into holes if threatened
          • Fairy Basslets - remain close to reef and keep belly hovering just over substrate
        • Some species are nocturnal (Cardinalfishes, Squirrelfishes)
          • distinguished by large, sensitive eyes
          • hide under corals during day
      • Effects of Planktivores
        • Affect density and composition of zooplankton passing over reef
        • have potential to influence the abundance of larval forms leaving a reef or approaching to settle
        • may be important source of coral mortality during coral spawning season
        • Study at Poor Knights Islands - high biomass of planktivorous fish helped support large population of piscivores
        • eat plankton offshore but defecate throughout the day on the reef - fecal material, not zooplankton, actually reaches the reef surface
        • bring new material into the reef economy by foraging out into the seaward water column and retain reef materials that would otherwise be swept off the reef and out to sea (Hammer et al 1988)
4. Detritivores: Consume dead organic material and return nutrients to the sediment.
   • Definition of dead organic material: animal and plant remains, waste products, and the bacteria/microorganisms associated with waste products
   • At least 3 reef fish families have been identified as feeding heavily on detritus in what is called the "epilithic algal matrix": Surgeonfishes, damselfishes, and blennies
   • Hard Substrate Detritivores (most members of the Ctenochaetus genus)
     • feeding technique: press jaw against substrate and then throw lower jaw upward
     • effectively brushes particulate matter off of rock and dead corals, and also out of turf algae
   • Sediment Detritivores
     • feeding technique: eat mouthfuls of sand and associated debris
     • Example: orange-shoulder surgeonfish
     • Example: Spotted Surgeonfish - Feeds by whisking comb-like teeth over the bottom as it closes its mouth
   • Algal Detritivores
     • Technique: scape algae off of hard surface, along with associated filamentous algae, diatoms, detritus, and sand (eat some algae, but primary source of nutrition is detritus within algae)
     • Example: Combtooth Blennies
   • "Mucus-munchers"