Structure and Function Animal Systems I Structure and Function

Feeding and Digestion Filter Feeders Detritivores Carnivores Strain their food from water Detritivores Feed on detritus, often obtaining extra nutrients from bacteria, algae and other microorganism nearby Carnivores Eat other animals Herbivores Eat plants or parts of plants in terrestrial and aquatic habitats Nutritional Symbionts Dependent on another species Parasitic Symbionts Live within or on a host where they feed on tissue, blood, or other body fluids Mutualistic Symbionts Both participants benefit

Processing Food Intracellular Digestion Extracellular Digestion Digestion of food inside specialized cells that pass nutrients to other cells by diffusion Example: sponges Extracellular Digestion Process in which food is broken down outside cells in a digestive system and then absorbed Gastrovascular Cavities Digestive cavity with a single opening Example: cnidarians Digestive Tracts Tube that begins at the mouth and ends at the anus Examples: many invertebrates and all vertebrates

Specializations for Different Diets Specialized Mouthparts and Digestive Tracts Eating Meat Sharp teeth Jaw adapted for up and down movements Short digestive tracts that produce meat-digesting enzymes Eating Plant Leaves Adapted to rasping or grinding Jaw adapted for side-to-side grinding movements Long intestines or specialized pouches in the digestive tract for microbial symbionts to digest cellulose

Respiration Gas Exchange Gas Diffusion and Membranes All animals must exchange O2 and CO2 with their surroundings Gas Diffusion and Membranes Requirements for Respiration Large surface area with a moist, selectively permeable membrane Structures maintain a difference in the concentration of O2 and CO2 on either side of the membrane, promoting diffusion

Respiration in Aquatic Animals Diffusion Some aquatic invertebrates (cnidarians and flatworms), some amphibians, some sea snakes Gills Feathery structure specialized for the exchange of gases with water Most aquatic invertebrates, most aquatic chordates (other than reptiles and mammals) Lungs Place where gases are exchanged between the blood and inhaled air Aquatic reptiles and aquatic mammals

Respiration in Terrestrial Animals Respiration in Land Invertebrates Skin Earthworms Mantle cavities Land snails Book lungs Spiders Trachael tubes Insects

Respiration in Terrestrial Animals Lung Structure in Vertebrates - Lung structure varies, but process of inhaling and exhaling is the same Amphibian, Reptilian, Mammalian Lungs Internal surface area increases from amphibian reptile mammal Mammals have alveoli to increase surface area for gas exchange Air moves in and out through trachae Some stale, oxygen-poor air is trapped in the lungs In humans, this is about 1/3 the air inhaled in a normal breath

Respiration in Terrestrial Animals Bird Lungs Air flows mostly in 1 direction No stale air gets trapped System of tubes and air sacs Highly efficient; enables birds to obtain O2 needed to power long flights at high altitude

Circulation Heart Open Circulatory System Hollow, muscular organ that pumps blood around the body Open Circulatory System Blood is only partially contained within a system of blood vessels as it travels through the body Has one or more hearts or heart-like organs to pump the blood Examples: arthropods and mollusks

Circulation Closed Circulatory System Blood circulates entirely within blood vessels that extend throughout the body A heart, or heart-like organ, forces blood through the vessels Examples: larger, more active invertebrates, including annelids, some mollusks, and all vertebrates

Circulation in Vertebrates Single-Loop Circulation Single pump forces blood around the body in one direction Most vertebrates with gills

Circulation in Vertebrates Double-Loop Circulation First loop: oxygen poor blood from heart to lungs; returns blood to the heart Second loop: pumps oxygen rich blood to the body; returns oxygen poor blood to the heart Terrestrial vertebrates Amphibians: 3 chambered heart; 2 atria, 1 ventricle Reptiles: 3 chambered heart; 2 atria, 1 ventricle with a partial partition in the ventricle Birds and Mammals: 4 chambered heart; 2 atria, 2 ventricles

Excretion The Ammonia Problem Created by the breakdown of proteins by cells It is poisonous! Animals either eliminate ammonia from the body quickly or convert it into other less toxic nitrogenous compounds Excretion - The elimination of metabolic wastes, such as ammonia - Small animals in aquatic environments can diffuse ammonia from the skin - Larger animals, and smaller ones that live in dry environments, have excretory systems to process and eliminate ammonia

Excretion Storing Nitrogenous Wastes Maintaining Water Balance Uric Acid Less toxic than ammonia sticky, white compound Less water soluble Insects, reptiles, birds Urea Highly soluble in water Mammals and some amphibians Maintaining Water Balance Kidneys organs of excretion that separate wastes and excess water from blood Efficient but cannot excrete excess salt

Excretion in Aquatic Animals Freshwater Animals Water concentration is higher in environment than in animal’s body Water moves into animal’s body by osmosis Flame cells: remove excess water from body fluids in flatworms Dilute urine: amphibians and freshwater fishes Animal would blow up like a balloon otherwise!

Excretion in Aquatic Animals Saltwater Animals Water concentration is similar to environment Salt concentration is higher in environment than in animal’s body Water moves out of the animal’s body by osmosis Kidneys produces small amounts of concentrated urine to conserve water Animal would shrivel otherwise!

Excretion in Terrestrial Animals Terrestrial Invertebrates Nephridia Tube-like excretory structures that filter body fluid Annelids, mollusks Malphigian Tubules Structures that concentrate the uric acid and add it to digestive waste Insects, arachnids

Excretion in Terrestrial Animals Terrestrial Vertebrates Kidneys Ammonia  urea  urine: mammals, land amphibians Ammonia  uric acid: reptiles, birds Adaptations to Extreme Environments Petrel: birds with specialized glands in their heads to excrete salt Kangaroo rats: urine that is 25x more concentrated than their blood