Feeding Mechanisms in Animals PDF

Feeding mechanisms in animals Objectives At the end of the lecture, students should be able to: State the source of food for animals. Define terms such as autotrophic nutrition, heterotrophic nutrition, holozoic nutrition and filter feeding. Comment on feeding adaptations in different gr...

Feeding mechanisms in animals Objectives At the end of the lecture, students should be able to: State the source of food for animals. Define terms such as autotrophic nutrition, heterotrophic nutrition, holozoic nutrition and filter feeding. Comment on feeding adaptations in different groups of organisms.  Feeding mechanisms in animals Autotrophic nutrition Production of complex organic compounds from simple inorganic molecules using energy from light (by photosynthesis) or inorganic chemical reactions (chemosynthesis). Green plants use the sun’s solar energy, carbon dioxide (that leaves take from the air) and water from the soil to synthesize sugars e.g. Glucose and indirectly all plant parts. Green plants are autotrophs/producers http://tomatosphere.org/teachers/guide/background-information/photosynthesis  Feeding mechanisms in animals Animals need food o To provide energy required to keep alive and to maintain body processes, for muscle contraction and many other processes. o As raw materials for building and maintaining cellular and metabolic processes. o For growth and reproduction. Heterotrophic nutrition o Nutrition of organisms that need readymade complex organic molecules obtained directly from plants or from organisms that have fed on plants. o All animals cannot make their own food. They depend on green plants directly or indirectly for their food supply. o All animals and non-green plants are called heterotrophs and their mode of nutrition is called heterotrophic nutrition. o Heterotrophs are the consumers in the ecosystem.  Feeding mechanisms in animals Heterotrophs can be classified into the following types depending on their feeding habits: Herbivores e.g., deer, cow, rabbit, sheep, giraffe, elephant, etc. Carnivores e.g., lion, tiger, lizard, hyaena, etc. Omnivores e.g., cockroach, human beings, dogs, etc. Parasites e.g. roundworm and tapeworm are parasites in the human intestine. Saprophytes Organisms that feed on dead and decaying organic matter e.g., mushroom, earthworm and some bacteria. Scavengers Animals that feed on dead animals e.g., vulture, jackal, crow, etc.  Feeding mechanisms in animals Holozoic nutrition (Greek holo -whole ; zoikos -of animals) o A method of nutrition that involves the ingestion of liquid or solid organic material, digestion, absorption and assimilation of the food to utilize it. o A type of heterotrophic nutrition. It involves: o Ingestion: Taking in complex organic food through mouth opening. o Digestion: Change of complex food into simple form by action of enzymes. o Absorption: Passing of simple, soluble nutrients through blood or lymph. o Assimilation: Utilization of absorbed food for various metabolic processes. o Egestion: Expelling out the undigested food. All animals and humans carry out this mode of nutrition.  Feeding methods & adaptations in animals Feeding on small particles of food Formation of digestive or food vacuoles E.g. Amoeba & paramecium They eat algae, bacteria, plant cells, microscopic protozoa, among others. Food material (e.g. microscopic algae) is enclosed in food vacuoles bounded by cell membrane. - Pseudopodia for movement and feeding Digestive enzymes are poured into the newly formed vacuole from the surrounding cytoplasm. Products of digestion are absorbed into the surrounding cytoplasm, and the waste material is ejected.  Feeding methods & adaptations in animals Formation of digestive or food vacuoles In paramecium, food vacuoles form at the cytopharynx. Cilia - hair like appendages help the paramecium move food into the oral groove. Oral Groove - collects and directs food into the cell mouth  Feeding methods & adaptations in animals Use of cilia in feeding E.g. Ciliates, sponges Many ciliates are filter feeders. They randomly strain (sieve) food particles from water. Ciliates create water currents with special ciliary structures associated with the cytostome (cell mouth). The synchronized beating of cilia pushes a stream of water against a membranelle (composed of cilia), which acts as a collecting sieve where the food particles become trapped in free spaces between the cilia.  Feeding methods & adaptations in animals Use of cilia in feeding e.g. Sponges Sponges: Are multicellular animals of the Phylum Porifera (“pore bearing”). Bodies full of pores and channels (allow water to circulate through them). Rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. Feed mostly on bacteria and small organic particles they filter from seawater pumped through their internal chambers. Food is captured on choanocytes (special “sieve” cells). Microvilli (in collar) filter nutrients http://www.realmagick.com/sponge- from water flowing across them. anatomy/ Food particles are then phagocytosed by the cell (Anderson, 2001). Feeding methods & adaptations in animals Sponge. Watch video on it  Feeding methods & adaptations in animals Filter feeding a method of feeding in which food particles or small organisms are randomly strained (sieved) from water. Found primarily among the small to medium-sized invertebrates but occurs in a few large vertebrates (e.g., flamingos, baleen whales). In bivalves (Phylum Mollusca, Class Bivalvia) such as clam, - the gills (for respiration) also function to strain suspended material out of water. - Hairlike filaments (cilia) produce water current over the gills. Other cilia move trapped food particles along the gill face and into food grooves.  Feeding methods & adaptations in animals Filter feeding Blue whale (Phylum Chordata; Class Mammalia; Order Cetacea) Cetacean – any member of an entirely aquatic group of mammals commonly known as whales, dolphins and porpoises. Baleen whale (toothless whale) possesses unique epidermal modifications of the mouth called baleen, which is a keratinized structure like hair, fingernails and hooves. Baleen or whalebone replaces the teeth. These narrow vertical plates, hang inside the mouth cavity in two transverse rows, one from each side of the roof of the mouth. Baleen whales seek out concentrations of small planktonic animals, open their mouth and take in enormous quantities of water. They squeeze the water out through the sides, trapping the shrimplike krill (small shrimplike planktonic crustacean of the open seas) on the baleen’s bristles. Feeding methods & adaptations in animals Feeding methods & adaptations in animals Krill Swarm. Watch video on it  Feeding methods & adaptations in animals Formation of Mucus traps E.g. Gastropods (snails and slugs) Many species: sea snails and slugs, freshwater snails, freshwater limpets, land snails and slugs. Very diverse including carnivores, herbivores, scavengers, filter feeders. Filter feeders use gills or nets of mucus to trap their prey, which they pull into the mouth with radula.  Feeding methods & adaptations in animals Use of tentacles (tentacular feeding) E.g. sea cucumbers (Phylum Echinodermata, Class Holothuroidea) Marine animals with a leathery skin and an elongated body. They live on or near the ocean floor, sometimes partially buried beneath it with tentacles above. Tentacles (tube feet) trap tiny particles like algae, minute aquatic animals, or waste materials/detritus for food.  Feeding methods & adaptations in animals Feeding on fluids or soft tissues Uptake through body surface e.g. Some parasites, tapeworms External digestion of food and sucking of soft tissue e.g. Spiders Ingestion of blood e.g. Ticks, insects, leeches.  Feeding methods & adaptations in animals Feeding on large food particles Ingestion of inactive masses Detritus feeders E.g. earthworm Detritus: non-living particulate organic material. It includes bodies of dead organisms. Scraping and chewing E.g. Gastropods and vertebrates Radula (radulae or radulas) is a minutely toothed, chitinous ribbon, typically used for scraping or cutting food before it enters the oesophagus. It is unique to molluscs, found in every class except bivalves. Snails radula at work http://en.wikipedia.org/wiki/Mollusca  Feeding methods & adaptations in animals Gastropods (snails and slugs) Very diverse including carnivores, herbivores, scavengers, filter feeders. Both herbivores and carnivores use radula. Land-dwelling species can chew up leaves, bark, fruit and decomposing animals while marine species can scrape algae off rocks on the sea floor.  Feeding methods & adaptations in Vertebrates Feeding Mechanism in Vertebrates Morphological/Anatomical mouth parts, powerful jaws, tongues, teeth appendages e.g. specialized claws and fingers for apprehending or killing Physiological/Biochemical Camouflage Buccal/oral secretions e.g. venom Behavioural Thanatosis (feigning death) as a defensive response e.g. invertebrates (ants, beetles, spiders) & vertebrates: snakes (e.g. brown snakes Storeria dekayi) lie in wait stalking e.g. lion or lioness, cat Hunt; setting up traps, etc.  Feeding methods & adaptations in Vertebrates Fishes Cyclostomes Primitive aquatic jawless vertebrate (Class Cyclostomata) such as lamprey & hagfish. tepapa.govt.nz Have a round sucking mouth and pouchlike gills Hagfishes - almost blind, but have well developed senses of touch and smell - eel-like scavengers (feed on the insides of dead & dying zoology.ubc.ca fish). Also eat marine invertebrates e.g. polychaete worms - have four pairs of sensing tentacles around their mouth - are equipped with two pairs of tooth-like rasps on the top of a tongue- like projection for feeding. Knot tying helps tear pieces of food.  Feeding methods & adaptations in Vertebrates Fishes Lampreys Sea lampreys are filter feeders as larvae but predatory parasites as adults. Feeding adaptations include Suctorial mouth is adapted for obtaining liquid food e.g. body fluids of other fish. Rasping tongue bearing tooth-like cusps. Can cause serious wounds on fish. myweb.ttu.edu  Feeding methods & adaptations in Vertebrates Bony fishes Most fish are carnivorous, feeding on worms, snails, other fish, insects etc. Mosquito fish (Gambusiaaffinis) - e.g. mackerels & tunas (family Scombridae) are active predators. Some are herbivores (e.g. parrotfish), omnivores or detritivores. Size and position of mouth indicates food size and mode of feeding. - Bottom feeders usually have down positioned mouths e.g. cat fish - surface feeders - upward positioned mouth https://en.wikipedia.org - open water feeders - symmetrical mouths. /wiki/Catfish  Feeding methods & adaptations in Vertebrates Bony fishes Feeding adaptations include: large canine teeth grasp its shelled prey. Blunt molars crush shells. E.g. wolf eel chisel-like teeth for eating algae e.g. parrotfish week.divebums.com (family Scaridae). Production of strong electric current to stun prey. E.g. Electric catfish (Malapterurus electricus) can produce 350 volts of electricity. picking debris and parasites from larger fishes. E.g. cleaner wrasse (Labroides dimidiatus) Light organs Bottom-dwelling deep sea species can produce light (bioluminescence) to attract prey. E.g. anglerfishes webexhibits.org  Feeding methods & adaptations in Vertebrates Electric organ (typically located in the tail of the electric fish) Electrogenic fish can generate electric fields. E.g. electric eel (Electrophorus electricus), electric rays, electric catfishes. Most electrogenic fish are also electroreceptive (Alves-Gomes, 2001) The electrical output is called electric organ discharge (EOD). Electroreceptive fish can detect electric fields e.g. sharks, rays and catfishes. - They are not classified as electric fish (cannot generate electricity). - Can detect weak electric fields produced by prey. Venomous fishes Venom immobilizes prey when injected into it. E.g. Stonefishes (e.g. Synanceia verrucosa), lionfish Lionfish (Pterois antennata)  Feeding methods & adaptations in Vertebrates Amphibians Feeding adaptations include: Long sticky tongue fastened at the front of its mouth. Tongue flicks in and out to catch its prey. Large and broad mouth to capture and eat large prey Tiny "teeth" on upper jaw & the roof of mouth of frog mainly used to hold prey. Broad flat skull for holding prey Large and bulging eyes on top of head for wide angled vision. The frog pulls its eyes down into the roof animal-zone.com of its mouth to help push food down its throat.  Feeding methods & adaptations in Vertebrates Reptiles Reptilian skull ranges from the reduced, loosely joined, or kinetic skull of snakes to large, solid skull of crocodiles. Kinetic skull of snakes - long and flexible quadrate bones (connect lower jaw to skull in snakes) allow movement of skull bones & snakes to swallow large prey - Lower jawbones joined by flexible band of tough tissue enables the two bones to articulate separately. Bush viper feeding rcreptiles.com deviantart.com  Feeding methods & adaptations in Vertebrates Reptiles Venomous snakes Examples: Indian cobra (Naja naja), tiger snakes (Notechis sp.) found in Australia, black mamba (Dendroaspis polylepis) found in Africa. have venom glands and fangs visual.merriam-webster.com Venom paralyzes prey. Snakes with pit organs E.g. python, rattlesnake & pit vipers have special heat-sensitive pit organs on their heads. Pit organs enable them track & strike Infrared thermal radiation from rat nature.com warm-blooded prey.  Feeding methods & adaptations in Vertebrates Reptiles Pythons A family of non-venomous constrictors. Bite and coil around the prey to kill Water Python (Liasis fuscus) it by suffocation. They usually find the www.oceanwideimages.com/ head and begin to swallow prey. Ball or royal python feeding (Python regius) justaboutballz.com  Feeding methods & adaptations in Vertebrates Reptiles Crocodiles Eat almost anything they can overpower, ranging from turtles, snakes, birds, mud crabs, monkeys, buffalo, humans. Juveniles eat insects, crustaceans, small reptiles, frogs & small fish. Strong jaws and teeth (thecodont and homodont dentition), elongated mouth and robust skull.  Feeding methods & adaptations in Vertebrates Lizards e.g. Chameleon Feed on insects, fruits Highly unique projective tongues Camouflage Wide angle vision www.chamaeleonidae.com/.../shapeimage_1.png Feeding methods & adaptations in Vertebrates Chameleon hunting flies. Watch video on it  Feeding methods & adaptations in Vertebrates Birds Bird bill is shaped according to what a bird eats. Duck (prying/digging) Night hawk (grain eating) Gull (scavenging/pecking) Cross bill (seed eating) Parrot (nut cracker) Kiwi (probes soil) Flamingo (mud sifter).  Feeding methods & adaptations in Vertebrates Birds The shape of feet reflects their habitat & type of food they might eat. arthursclipart.org  Feeding methods & adaptations in Vertebrates Mammals Bats: most are insectivorous (catch most insects while in flight at night). - Small eyes used in daytime or when there is bright moon. - Navigation and hunting accomplished mainly with echolocation. -- Bat can gather information from the echoes e.g. size, shape, distance of object and whether it is moving. - Sharp teeth for chewing. Some bats eat fruit, blood, pollen, nectar, fish, other small vertebrates. Echolocation poorly developed and eyes are large in fruit-eating bats.  Life in the deep seas – Source of food Food source in deep ocean Rich animal communities occur in several places of undersea volcanic activity where rigid plates of the earth’s crust pull apart. - Total darkness at a depth of several Hydrothermal vent thousand meters? No light, en.wikipedia.org no green plants. - Their existence is completely independent of food chains based on photosynthesis. - What is their source of food? Hydrothermal vent Volcanic fissures in a planet's surface from which geothermally heated water issues.  Life in the deep seas – Source of food Water from the vents contains a variety of dissolved minerals and high concentrations of hydrogen sulphide. This water mixes oxygen-rich ocean water and H2S gets oxidized to S. There is tremendous production of bacteria that obtain chemical energy from the oxidation of H2S (Karl et al., 1980). Bacteria absorb H2S from the vents, oxidize it and use chemical energy released during oxidation to combine carbon, hydrogen and oxygen into sugar molecules.  Life in the deep seas – Source of food Filter feeders e.g. clams and mussels thrive on filtering out these bacteria. Predatory animals like crabs feed on other animals. Food chain begins with the bacteria and is based on chemical energy (from H2S oxidation).