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Planktivory. Sponges. Jellyfish. Filter feeding in Aurelia (Moon Jelly). Corals. Hermatypic. Ahermatypic. Bivalves. lancet. Christmas tree worms. Filter feeding in Krill. the six thoracopods form a very effective "feeding basket". Barnacle feeding. Modified legs. tunicate.
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Jellyfish Filter feeding in Aurelia (Moon Jelly)
Corals Hermatypic Ahermatypic
Filter feeding in Krill the six thoracopods form a very effective "feeding basket"
Barnacle feeding Modified legs
tunicate Oikopleura Predator Filter feeder
Planktivory Suspension feeders: Animals that process large quantities of water through a feeding apparatus (gill rakers, baleen). Gill rakers trap particles such as zooplankton, phytoplankton and detritus.
Includes: manta rays, basking shark, whale shark, megamouth, paddlefish, gizzard shad, menhaden, and bighead carp.
Feeding strategies: • A) Obligate and faculative planktivores: • Most fish are planktivorous at some point in their life, either as holoplankton or meroplankton. • Facultative planktivores: (ex. sunfishes) are opportunistic feeders. Prey selection depends on food availability • Obligate planktivores: (ex. blueblack herring, Atlantic Menhaden) feed exclusively on plankton
B) Ram feeding and suction feeding • Ram feeding: creates a forward motion in which water is delivered into the mouth; opens mouth wide as possible and rams prey • continuous ram feeders • intermittent ram feeders • Suction feeding: predator remains relatively stationary, comes close to prey and then sucks prey in. • continuous suction feeders • intermittent suction feeders Suction feeder Nonsuction feeder
Jaw Protrusion Sling-jaw wrasse
Ram Feeders • Continuous • Intermittent
Continuous ram feeders (tow-net)- water passes continuously through mouth, over gills and exits through gill slits or operculum. ~20 species fish In fish: extensive elaboration of the branchial (gill) apparatus
Manta Ray: • They have no teeth. • Cephalic flaps channel water containing plankton into mouth • To prevent gills from clogging, a screen of small tiny protuberances located in the throat, hold the food until it can be swallowed.
Megamouth, Basking Shark and Whale Shark- Generally these planktivorous sharks have tiny numerous teeth and elongated gill rakers. The gill rakers help to strain plankton.
Basking shark- (10 meters long) • Swims about 2 knots with mouth open and bristle-like gill rakers erect while filtering particulate matter • It then closes its’ mouth forcing water over the gills; it is an indiscriminate planktivore • Has five pairs of gill slits and can filters ~540 liters zooplankton/day and over 1500 gallons of water/ hour (1850 m3 water/hour)
Basking Shark Dentition (A) Labial, (B) basal and (C) lateral views of basking shark teeth, ex Compagno (1990) NOAA Tech. Rep. NMFS 90,D) Enlarged photo of a portion of jaw,ex Radcliffe (1916) Bull. Bur. Fish. Circ. 822
Basking Shark Gill Arches • Gill rakers shed during cold months. • May be hibernation
Paddlefish- Order Acipenseriformes • freshwater, rarely brackish; found in China and the US • gill rakers are long and in the hundreds- used for plankton feeding, minute teeth are present • Polyodon spathula (US- Mississippi drainage)- plankton-feeding; non protrusible mouth • Psephurus gladius (China- Yangtze River)- piscivorous with a protrusible mouth
Intermittent ram feeders • takes one gulp of water at a time, extracts particles and repeats the process • In using this method, the predator needs to be able to grab prey before it moves out of the way. • Seen in whales, not sure about in fish????
Suction Feeders • Continuous • Intermittent
Continuous suction feeders (pump filter feeders)- creates and osculatory pump and draws water in over sieving device. Animal remains still while suctioning. Ammocetes (lamprey larvae)-spends 3-7 years filter feeding and burrows into sand;
Intermittent suction feeders (intermediate feeding): • relatively unspecialized • intermediate condition between ram and suction feeding on individual prey • they don’t alter their swimming speed or direction to focus attention on individual plankton.
Diurnal Planktivores Typically feed by forming aggregations in the water column prey- swimming crustacea, larvaceans and fish eggs
Diurnal Planktivores • modifications to jaw, head and dentition: usually small mouth, reduced or absent teeth • jaw protrusion mainly functions to produce suction • Can feed on zooplankton smaller than 1mm
Diurnal Planktivory • Adaptations • streamlining • deeply forked caudal fins • aggregation
Crepuscular changeover- diurnal fish leave typically in order of: small fish first….mid sized …. then large Very active time. In nocturnal species- fish enter waters above the reef at night fall by size order (small to larger)
Nocturnal Planktivores • Difficulty in visually locating prey in dim light • adaptation- large eyes ex. squirrel fish • Feeding on zooplankton larger than 1 mm • Possibly due to: • 1.) inability to see smaller ones • 2.) more efficient • 3.) prey more vulnerable
Adaptations to nocturnal threats from predators: • streamlined bodies and deeply forked tails are less developed • less aggregation occurs at night • countershading using luminescent organs • Nocturnal planktivores more widespread throughout reef than diurnal counterparts
Inquiry • Describe key characteristics of nocturnal and diurnal planktivorous fish. • What types tools do animals use to catch plankton. • What is the advantage and disadvantage of jaw protrusion?