Feeding & Digestion Why eat? • Macronutrients Feeding & Digestion – Energy for all our metabolic processes – Monomers to build our polymers 1. Carbohydrates 2. Lipids 3. Protein • Micronutrients – Tiny amounts of vital elements & compounds our body cannot adequately synthesize 4. Vitamins 5. Minerals • Hydration 6. Water Niche: role played in a FEEDING community (grazer, predator, • “Eat”: Gr. -phagy; Lt. -vore scavenger, etc.) • Your food may not Some organisms have specialized niches so as to: • increase feeding efficiency wish to be eaten! • reduce competition • DIET & Optimal foraging model: Need to maximize benefits (energy/nutrients) while minimizing MORPHOLOGY costs (energy expended/risks) • FOOD CAPTURE • MECHANICAL PROCESSING Never give up! Optimal Foraging Model Optimal Foraging Model • Morphology reflects foraging strategies • Generalist is less limited by rarity of resources • Specialist is more efficient at exploiting a specific resource Generalist OMNIVORE opossum CARNIVORE HERBIVORE wolf elephant Optimal foraging strategies: Need to maximize benefits (energy/nutrients) INSECTIVORE PISCIVORE while minimizing costs (energy shrew osprey expended / risks) MYRMECOPHAGORE • Tapirs have 40x more meat, but are anteater much harder to find and catch. Specialist So jaguars prefer armadillos. Heyer 1 Feeding & Digestion Bird Beaks Anteater Adaptations • Generalist & specialist bills • Thick fur • Small eyes • Long claws in front • Long snout • Long barbed tongue • No teeth FOOD CAPTURE SPECIALIZATIONS Fluid Feeding – Fluid Feeding • Sucking with tube – Suspension & Deposit Feeding – mosquitoes & butterflies • Lapping with brushy tongue – Grazers & Browsers – hummingbirds, fruit bats – Predation: Ambush & Attraction – bees – Venoms – Tool Use & Team Efforts Hummingbird tongue Suspension Feeding (Filter Feeding) • Filter food (plankton, small animals, organic particles) suspended in water. • http://www.youtube.com/watch?v=1wpQ8HQEkvE • Filters are hard, soft or even sticky. Heyer 2 Feeding & Digestion Suspension Feeding (Filter Feeding) • Barnacles: “little shrimps that glue their heads to suspension a rock and catch food with their feet” feeding in baleen whales Right Whales — “sippers” suspension • Skim feeding feeding in baleen whales • Baleen is tough but flexible filter composed of the protein keratin. • The length of the baleen depends upon the feeding style of the whale Rorquals — “gulpers” Grey Whales — “mud suckers” • Lunge feeding Heyer 3 Feeding & Digestion Suspension feeding in fish — gill rakers Suspension Feeding • Raker spacing determines prey size. in extinct pterosaurs – If a habitat has two similar species, they diverge in gill raker spacing. • A pterosaur filters plankton in a lake – Reducing niche overlap is called resource partitioning or niche divergence. Two species of shad Sticky Filters Sticky Filters • Glue of spider webs • Mucus nets • Cnidocytes (stinging cells) of jellyfish. – Larvaceans • Collar cells of sponges – Spoon worms & lug worms Giant larvacean “house” Deposit Feeders Grazers & Browsers • Detritivores: feed on decomposing particles • Grazers: feed on fast growing, abundant, short & associated microorganisms deposited on/in vegetation (terrestrial grasses; aquatic turf algae) sediment/soil Earthworms swallow & digest organic or encrusting animals material in soil as they burrow. – Slow moving, methodical Sea cucumber mops detritus – Mouth-parts for cropping or scraping food close to substrate off sediment surface. – Grasses low moisture content: need water to drink • Browsers: feed on taller vegetation (leaves, bark, etc.) – More selective; more mobile to locate patches – Food moisture may be adequate – More anti-herbivore defenses (thorns, toxins, etc.) Heyer 4 Feeding & Digestion Grazers & Browsers Grazers & Browsers • Grazers: feed on fast growing, abundant, short vegetation (terrestrial grasses; aquatic turf algae) or encrusting animals – Slow moving, methodical – Mouth-parts for cropping or scraping food close to substrate – Grasses low moisture content: need water to drink • Browsers: feed on taller vegetation (leaves, bark, etc.) – More selective; more mobile to locate patches – Food moisture may be adequate – More anti-herbivore defenses (thorns, toxins, etc.) Ambush Predators • Crab & trap door spiders, Komodo dragons, lions, Ensnare Prey etc. • Works best if animal has • Bolas spiders snag 'em, cryptic coloration. onycophorans slime 'em. Toxins Attraction • Poison saliva is used by shrews & cephalopods • Chemical Lures – bolas spider mimics female moth pheromone • Visual Lures – Fireflies – Snapping turtles – Angler fish Heyer 5 Feeding & Digestion Inject Toxins (Venom) Neurotoxins Immobilize Prey • Block neurotransmitters that control movement. • Prevent escape and/or harm to predator. • Fangs: spiders or snakes • Stingers: wasps and scorpions Tissue-destructive Toxins Team Efforts Digest Prey • Team up to capture larger/faster prey – social canids – lions – orcas • Scorpions & spiders have external digestion. • Rattlesnakes consume VERY large prey. Tool Use Digestion • Galapagos finches, ravens, & Egyptian vultures • The hydrolysis (breakdown) of large food molecules • Chimps & sea otters (polymers) into small organic subunits (monomers). • The monomers may then be used for: § Metabolic fuel (cellular respiration → ATP & heat) or § Subunits to build new polymers q Hydrolysis is catalyzed by enzymes § May be intracellular or extracellular Heyer 6 Feeding & Digestion Hydrolytic Enzymes Hydrolytic Enzymes • Hydrolysis reactions catalyzed by enzymes • Most plant material is largely cellulose – enzyme names end with “-ase” • Yet no animal has enzymes that can digest cellulose • Amylase: hydrolyze carbohydrates • Most herbivores depend upon • Protease: hydrolyze proteins symbioses with cellulytic protists in • Peptidase: hydrolyze peptides their guts • In turn, the cellulytic protists depend • Lipase: hydrolyze lipids upon symbioses with bacteria to produce the actual enzymes Intracellular Digestion Intracellular Digestion 1. phagocytosis 2. ð food held in vacuole Protists, 3. ð vacuole fuses with lysosome sponges, filled with digestive enzymes some 4. ð food digested cnidarians 5. ð excytosis of indigestible material Paramecium Extracellular Digestion Internal Digestion & Food Processing 1. enzymes secreted into space 1. Ingestion (lumen of digestive tract) – Consuming food 2. ð food broken into small molecules 2. Physical disruption 3. ð absorption by cells lining the – Mastication, dissolution, denaturation, emulsification digestive tract 3. Motility 4. expulsion of indigestible material – Swallowing, peristalsis, segmentation, defecation 4. True digestion – Hydrolysis of polymers into monomers 5. Absorption – Moving nutrients from G.I. Tract into circulatory system 6. Assimilation – Incorporate nutrient molecules into tissues Heyer 7 Feeding & Digestion Ingestion for Internal Digestion Ingestion for Internal Digestion 1. Ciliary (or flagellar) motility 1. Ciliary (or flagellar) motility 2. Oral appendages a. Ciliary b. Grasping / Sweeping 3. Protrusable / prehensile structures a. Pharynx b. Jaws 4. Swallowing a. Ram / Gravity / Lunge / Suction b. Pharyngeal / Ratcheting jaws Ctenophore irridescent comb rows [ctenes] of ciliated plates c. Lingual for both propulsion & feeding currents https://www.youtube.com/watch?v=GGFrcWD2jYA Ingestion for Internal Digestion Ingestion for Internal Digestion 2. Oral appendages 3. Protrusable / prehensile structures a. Ciliary a. Pharynx b. Grasping / Sweeping b. Jaws Ciliated oral tentacles of a spaghetti worm “Mouth field” feeding appendages of a shrimp Eversible jawed pharynx of Bloodworm Slingjaw wrasse https://www.youtube.com/watch?v=mktMxLrU8rA https://www.youtube.com/watch?v=pDU4CQWXaNY Ingestion for Internal Digestion Ingestion for Internal Digestion 4. Swallowing 4. Swallowing a. Ram / Gravity / Lunge / Suction b. Pharyngeal / Ratcheting jaws Pharyngeal jaws in a moray eel Disarticulation & Suction feeding by Cichlid independent action of Lunge & gravity swallowing by Blue heron https://www.youtube.com/watch?v=TbGILi8p5Y8 https://www.youtube.com/watch?v=1-p2AI9uTs0 Odontophore in a snail snake jaw bones Suction feeding by Tiger fish https://www.youtube.com/watch? https://www.youtube.com/watch?v=m2lcBaqYK1o v=HP8Ocr3KJho Heyer 8 Feeding & Digestion Ingestion for Internal Digestion Internal Digestion — Digestive Tracts 4. Swallowing • Epithelial tissue lining a hollow cavity (lumen) c. Lingual • Ridges & wrinkles to increase surface area for absorption • Tongue of most vertebrates • Usually highly vascularized to transport absorbed materials – Intrinsic muscles — hydrostat – Extrinsic muscles — anchoring Mammalian gut Chameleon can extend tongue >1½x body length https://www.youtube.com/watch?v=YXbgRU4k3O8 Digestive Tracts Digestive Tracts • Gastrovascular systems (blind guts) • Complete guts – indigestible material regurgitated – Mouth ⇒ Anus Platyhelminth flatworm — Planaria Cnidarian polyp — Hydra Digestive Tracts Digestive Tracts • Complete guts • Complete guts – Mouth ⇒ Anus – Mouth ⇒ Anus Echinoderm seastar • Eversible cardiac • Muscular pharynx pushes food through non-muscular gut stomach for external digestion • Free-living roundworms feed on microbes • Pyloric stomach for • Parasitic roundworms feed on host body fluids internal digestion & • No need for much specialization of gut absorption Heyer 9 Feeding & Digestion Digestive Tracts Digestive Tracts • Complete guts • Complete guts – Mouth ⇒ Anus – Mouth ⇒ Anus typhlosole