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Introduction to animals Introduction to Animals Traits Characteristics of Animals • All multicellular (metazoans) • Eukaryotes (cells with nucleus & organelles) • Ingestive heterotrophs (take in food and internally digest it) • Store food reserves in the liver as glycogen Lions Feeding (Ingestion) Support Systems • Have some type of skeletal support • Endoskeleton inside and made of cartilage &/or bone • Exoskeletons found in arthropods – Cover the outside of the body – Limit size – Must be molted making animal vulnerable to predators Cicada Molting Exoskeleton Support Systems • Worms and echinoderms (starfish) have fluid-filled internal cavities giving them support • Called hydrostatic skeletons Movement • Animals such as sponges may be sessile (attached & non-moving) • Animals that move very little are said to be sedentary (clam) • Animals that can move are motile • Have muscular tissue to provide energy for movement SESSILE Sponge SEDENTARY Chiton MOTILE Cheetah Reproduction in Animals • sexual reproduction • Some like sponges and earthworms are hermaphrodites produce eggs and sperm • may exchange sperm and NOT fertilize their own eggs Leeches Exchange Sperm During Mating leech Mating Reproduction in Animals • Females of some animals produce eggs, but the eggs develop without being fertilized • Called Parthenogenesis • New offspring will be all female occurs in some fishes, several insects, and frogs and lizards Parthenogenesis in the Komodo Dragon Female Beetles Mating Courtship Young Male Mating and Mating Behaviors Levels of Organization • Sponges =ONLY animals with just cellular level • All others show– cell, tissue, organ, and system • Cells may specialize (take own different shapes and functions) • Cells held together by cell junctions to form tissues Atom Molecule or compound Levels of Organization Organ Tissue Organ system Organelle CELL Life begins Organism Invertebrate groups Characteristics of Invertebrates • Simplest animals • greatest number of different species • Most aquatic (found in water) • NO backbone • Includes sponges, cnidarians, flatworms, roundworms, annelids, mollusks, arthropods, and echinoderms Sponge - Porifera Osculum of Sponge Sponges and Cnidarians 20 Sea Anemone - Cnidaria Tentacles of Sea Anemone More Cnidarians Brain Coral Red jellyfish 23 Flatworms - Platyhelminthes Marine Flatworm Planarian Roundworms (Nematoda) and Segmented Worms (Annelida) Nematode Leech (segmented worm) Mollusca (With and Without Shells) snail nautilus scallop sea slug octopus Arthropoda (insects, spiders, crustaceans, horseshoe crab) spider crayfish Horseshoe crab Dung beetle Echinoderms Sea fan (crinoid) starfish Brittle star Sand dollar Sea cucumber Vertebrate Groups (Phylum Chordata, Subphylum Vertebrata) Vertebrata • More complex • backbone of vertebrae • simplest phylum to most complex: fish, amphibians, reptiles, birds, and mammals Vertebrate Backbone Vertebrata • endoskeletons (internal) • Some have skeletons of cartilage (sharks, rays, and skates) Bone & Cartilage in Fetus Fish lancelet ray damselfish anglerfish Amphibia salamander toad frog newt Reptilia Turtle Snake Lizard Alligator Reptiles 37 Birds - Aves hummingbird ostrich lovebirds Mammalia Body Areas Surfaces • • • • • • Dorsal – back Ventral – belly Anterior –front end Posterior –hind end Oral surface–mouth Aboral surface–opposite the mouth Surfaces (Most Animals) DORSAL POSTERIOR ANTERIOR VENTRAL Surfaces (Echinoderms) ORAL ABORAL mouth Symmetry Body Symmetry Body Symmetry • Symmetry = arrangement of body parts around central axis • Asymmetry Body Symmetry • Radial symmetry = body parts arranged around central point like spokes (echinoderms) – Most with radial symmetry are sessile (attached) or sedentary (move very little) Body Symmetry • Bilateral symmetry = divided into equal halves • right and left sides are mirror images • More complex Body Symmetry • bilateral symmetry, usually motile • anterior and posterior ends • Show cephalization concentration of sensory organs on the head Segmentation Segmentation • Earthworms show external segmentation • Humans show internal segmentation (backbone) • Segments may fuse (cephalothorax) Segmentation cephalothorax Tissues Tissue Development • Zygote (fertilized egg) undergoes rapid cell divisions =cleavage • Forms a hollow ball of cells =blastula Blastula •The blastocoel = center cavity of blastula with 1 germ layer (blastoderm) Tissue Development Archenteron • folds inward at one point =Gastrulation • opening =blastopore blastopore Tissue Development • Blastopore may become mouth (Protostome) or anus (Deuterostome) • Protostomes (mollusks, arthropods, & annelids) • Deuterostomes (echinoderms & vertebrates) • Some animals form a middle germ layer called mesoderm Embryonic Development Germ Layers • NOT present in sponges • Ectoderm (outer) – forms skin, nerves, sense organs • Endoderm (inner) – forms liver and lungs • Mesoderm (middle) – forms muscles & other systems Body Layers • All worms, mollusks, arthropods, echinoderms, and vertebrates have three cell layers – Ectoderm – Endoderm – mesoderm Stages of Development Larval Forms • Animals with Indirect development • Larva does NOT resemble adult • Cnidarian larva = Planula Larval Forms • Mollusk (squid & octopus) larva = trochophore • Echinoderm (starfish) larva is = Dipleurula Metamorphosis • Usually found in arthropods • May be complete or incomplete • Incomplete Metamorphosis: egg nymph adult • Complete Metamorphosis: egg larva pupa adult Metamorphosis COMPLETE INCOMPLETE Body Cavities Coelom - Body Cavity • Internal body cavity fully lined with mesoderm • Body organs suspended in this cavity Coelom - Body Cavity • Acoelomate =solid bodies filled with cells • Ex.sponges, cnidarians, & flatworms Coelom - Body Cavity • Pseudocoelomate = (roundworms) = functional body cavity NOT fully lined with mesoderm Animal Systems Support Systems • Spongin & spicules (sponges) • Limestone cases (corals) • Exoskeletons of Chitin (arthropods) – Must be shed or molted to grow • Inner Calcium plates (echinoderms) • Bone/cartilage endoskeleton (vertebrates) Digestive Systems • All animals = ingestive heterotrophs • Gastrovascular cavity with one opening in cnidarians & flatworms = two-way digestive system Two-Way Digestion Digestive Systems • one-way digestive system = mouth and an anus • Includes annelids, arthropods, & vertebrates One-Way Digestion Mouth anus Circulatory Systems • Transports oxygen & nutrients to cells • Carries away wastes & carbon dioxide from cells • Sponges, cnidarians, & flatworms do NOT have circulatory systems Circulatory Systems • In closed circulation, blood remains inside blood vessels until it reaches cells (annelids & vertebrates) • In open circulation, blood is pumped out of blood vessels to bathe tissues in the body cavity or hemocoel (arthropods & mollusks) Open Circulation Closed Circulation