Planktivory

Sponges

Filter feeding in Aurelia (Moon Jelly) Jellyfish

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

Predator Filter feeder Oikopleura tunicate

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.

Baleen

Includes: manta rays, basking shark, whale shark, megamouth, paddlefish, gizzard shad, menhaden, and bighead carp.

Flamingo

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 feederNonsuction 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 m 3 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

Continuous ram feeding

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 and Nocturnal 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 Planktivores

Adaptations streamlining deeply forked caudal fins aggregation Diurnal Planktivory

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)

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 Nocturnal Planktivores

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 1.Describe key characteristics of nocturnal and diurnal planktivorous fish. 2.What types tools do animals use to catch plankton. 3.What is the advantage and disadvantage of jaw protrusion?