Animal Diversity and Function

Animal Diversity and Function : Animal Diversity and Function


Animals are multicellular, heterotrophic eukaryotes that obtain nutrients by ingestion. : Animals are multicellular, heterotrophic eukaryotes that obtain nutrients by ingestion. Lack cell walls Cells are held together by extracellular matrix proteins and junctions Have muscle cells for movement and nerve cells for conducting impulses Diploid and reproduce sexually Egg and sperm are the only haploid cells


Sponges have a simple porous body : Sponges have a simple porous body Over 9,000 species of sponges and most are marine A simple sponge resembles a sac perforated with holes Simplest of all animals, have no nerves or muscles, they don’t really have tissues because the cells are relatively unspecialized Suspension feeders – feed by collecting bacteria from water that streams through their bodies then engulfing it by phagocytosis.


Radial symmetry : Radial symmetry The body parts are arranged like pieces of a pie around an imaginary central axis


Cnidarians – the hydras, jellies, sea anemones and corals : Cnidarians – the hydras, jellies, sea anemones and corals Most of the over 10,000 species are marine All have radial symmetry They are carnivores and use their tentacles to capture small animals and protists and push the prey into their mouths Have stinger cells on the surface of the tentacles that function in defense and prey capture Have a digestive cavity and true tissues.


Stinger cell action : Stinger cell action


Bilateral symmetry : Bilateral symmetry Means that an animal can be divided equally by a single cut and has mirror-image right and left sides. Dorsal – back Ventral – bottom Lateral - sides


Flatworms are the simplest bilateral animals : Flatworms are the simplest bilateral animals 20,000 species There are free living and parasitic forms Have an incomplete digestive tract Three major groups, free-living flatworms, flukes (parasites) and tapeworms (parasites)


Tapeworms : Tapeworms Inhabit the digestive tracts of vertebrate animals including reptiles, birds, and mammals Have no digestive tract Live in partially digested food in the intestine of their hosts and absorb nutrients across their body surface Several kinds infect humans and can grow up to 6m in length.


Roundworms : Roundworms Cylindrical worms with a blunt head and tapered tail Covered by a tough cuticle that resists drying and crushing (molts when it grows) Complete digestive tract 90,000 known species Trichinosis from pork


Mollusks – snails, slugs, oysters, clams, octopuses and squids : Mollusks – snails, slugs, oysters, clams, octopuses and squids More than 150,000 known species Most have a soft body protected by a hard shell Common features – muscular foot for locomotion, visceral mass with internal organs, and a mantle that covers the visceral mass, also have a radula to scrape up food


Mollusks body plan : Mollusks body plan Mollusks have a true body cavity consisting of three small cavities. One around the heart, the reproductive organs and the kidney Also have a circulatory system


Segmented body : Segmented body The subdivision of the body along its length into a series of repeated parts. Allows greater flexibility and mobility


Annelids are segmented worms : Annelids are segmented worms 15,000 species including the earthworms and leeches Earthworms till the soil and improve its texture Leeches secrete saliva that contains a strong anesthetic and an anticoagulant into the wound


Arthropods – crayfish, lobsters, crabs, barnacles, spiders, ticks, and insects : Arthropods – crayfish, lobsters, crabs, barnacles, spiders, ticks, and insects Largest phylum in terms of diversity, distribution and numbers Have jointed appendages Covered by a hard external skeleton called the exoskeleton (made of protein and a polysaccharide chitin)


Insects – The largest class of arthropods : Insects – The largest class of arthropods About a million insect species described so far Many undergo metamorphosis Complete metamorphosis the larval stages look very different from the adults (caterpillars – moths and butterflies and maggots – flies) Incomplete metamorphosis – the young resemble the adults but are smaller with different body proportions


Echinoderms – sea stars, sand dollars, sea urchins : Echinoderms – sea stars, sand dollars, sea urchins All 7,000 species are marine Lack body segments and most are radially symmetrical Can have hard spines or plates embedded under the skin which are actually part of the hard internal skeleton (endoskeleton) Can regenerate whole arms Water vascular system that branches into tube feet that are important in locomotion, feeding and gas exchange


Chordata : Chordata


Chordata distinctive features : Chordata distinctive features A dorsal, hollow nerve cord A notochord, a flexible supportive, longitudinal rod located between the digestive tract and the nerve cord Pharyngeal slits, gill structures in the pharynx, the region of the digestive tube just behind the mouth A muscular post-anal tail


Invertebrate chordates - tunicates and lancelets : Invertebrate chordates - tunicates and lancelets The tunicate larvae meets all four criteria of a chordate, but the adult is a stationary sac with no notochord, nerve chord or tail Lancelets are small chrodates that live in marine sand, they have all four chordate features and segmental muscles which allow them to swim slowly


Vertebrates – animals with a segmented backbone : Vertebrates – animals with a segmented backbone Distinguishing features are a skull and a backbone composed of a series of segmented units called vertebrae which enclose the main parts of the nervous system Most also have skeletal parts supporting their body appendages The skeleton is made of either flexible cartilage or a combination of hard bone and cartilage


Most vertebrates have hinged jaws : Most vertebrates have hinged jaws Sea lampreys are some of the few vertebrates without hinged jaws (two skeletal parts held together by a hinge) Lampreys have an unhinged toothed, sucking disk that bores a hole in the side of a fish and sucks its blood


Fishes – Jawed vertebrates with gills and paired fins : Fishes – Jawed vertebrates with gills and paired fins Gills extract oxygen from water Paired forefins and hindfins help maneuver the body when swimming. Nearly all fishes are carnivorous Bony fishes have a swim bladder, a gas filled sac that keeps them buoyant


Amphibians – living a double life : Amphibians – living a double life Most have both aquatic and terrestrial adaptations 4800 species Most are tied to water because their eggs dry out in the air When frog eggs hatch the tadpole is a legless aquatic algaepeater with gills and a tail. A young frog is a terrestrial insect-eater with four legs and air-breathing lungs.


Reptiles – lizards, snakes, turtles, crocodiles and alligators : Reptiles – lizards, snakes, turtles, crocodiles and alligators 6500 species Reptilian skin Covered with scales waterproofed with keratin Eggs have shells that retain water “cold blooded” – do not use metabolism to control body temperature


Birds : Birds About 8600 species Like reptiles, have amniotic eggs, scales on their legs, toenails containing keratin Many features help reduce weight for flight: lack teeth, tail has only a few vertebrae, feathers have hollow shafts, bones have a honeycombed structure High rate of metabolism and endothermic Excellent vision and relatively large brains


Mammals : Mammals Endothermic with a high rate of metabolism Hair and mammary glands that produce mild to nourish young are the hallmarks Three groups: 1. egg-laying (platypus) 2. marsupials have embryonic young that they then nurse in a pouch 3. a longer lasting association between mover and developing young


Humans threaten animal diversity by introducing non-native species : Humans threaten animal diversity by introducing non-native species


Structure fits function in the animal body : Structure fits function in the animal body


Structural hierarchy : Structural hierarchy


Tissues : Tissues A group of similar cells that performs a specific function


Epithelial tissue – covers and lines the body and its parts : Epithelial tissue – covers and lines the body and its parts


Connective tissue – binds and supports other tissues : Connective tissue – binds and supports other tissues


Muscle – functions in movement : Muscle – functions in movement


Nervous tissue – a communication network : Nervous tissue – a communication network


Organs – several tissues working together to perform a specialized function : Organs – several tissues working together to perform a specialized function


Imaging Technologies : Imaging Technologies X-rays – use radiation to see hard structures such as bones and dense tumors the rays are blocked by Computer tomography (CT scan) – X-rays aided by computers to visualize more soft tissues Magnetic Resonance imaging (MRI) – allows us to see soft tissues Positron-emission tomography (PET) – patient gets glucose for example, labeled with a radioactive isotope to view metabolic hot spots