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Introduction to animals

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Presentation on theme: "Introduction to animals"— Presentation transcript:

1 Introduction to animals

2 Traits

3 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

4 Lions Feeding (Ingestion)

5 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

6 Cicada Molting Exoskeleton

7 Support Systems Worms and echinoderms (starfish) have fluid-filled internal cavities giving them support Called hydrostatic skeletons

8 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


10 Reproduction in Animals
All animals are capable of sexual reproduction Some animals like sponges and earthworms are hermaphrodites producing both eggs and sperm Hermaphrodites may exchange sperm and NOT fertilize their own eggs

11 Leeches Exchange Sperm During Mating

12 Reproduction in Animals
Females of some animals produce eggs, but the eggs develop without being fertilized Called Parthenogenesis New offspring will be all female Parthenogenesis occurs in some fishes, several kinds of insects, and a few species of frogs and lizards

13 Parthenogenesis in the Komodo Dragon

14 Mating and Mating Behaviors
Female Beetles Mating Young Courtship Male Mating and Mating Behaviors

15 Levels of Organization
Sponges are the ONLY animals that have just the cellular level All other animals show these levels – cell, tissue, organ, and system Cells may specialize (take own different shapes and functions) Cells are held together by cell junctions to form tissues

16 Levels of Organization
Molecule or compound Atom Organelle Levels of Organization CELL Life begins Tissue Organ Organ system Organism

17 2 Divisions Invertebrates – animals without a backbone (95% of all animals) Vertebrates – animals with a backbone

18 Invertebrate Phyla Porifera – sponges
Cnidaria – sea anemones, hydra, jellyfish, coral Platyhelminthes – flat worms Nematoda – round worms Annelida – segmented worms, leeches Mollusca – univalves, bivalves, octopi, squid Arthropoda – insects, spiders, crustaceans, millipedes, centipedes Echinodermata – starfish, sea urchins, sea cucumbers

19 Invertebrate groups

20 Characteristics of Invertebrates
Simplest animals Contain the greatest number of different species Most are aquatic (found in water) Do NOT have a backbone Includes sponges, cnidarians, flatworms, roundworms, annelids, mollusks, arthropods, and echinoderms

21 Sponge - Porifera Osculum of Sponge

22 Sea Anemone - Cnidaria Tentacles of Sea Anemone

23 More Cnidarians Brain Coral Red jellyfish

24 Flatworms - Platyhelminthes
Marine Flatworm Planarian

25 Roundworms (Nematoda) and Segmented Worms (Annelida)
Nematode Leech (segmented worm)

26 Mollusca (With and Without Shells)
snail scallop octopus nudibranch nautilus

27 Arthropoda (insects, spiders, crustaceans, horseshoe crab)
crayfish Horseshoe crab Dung beetle

28 Echinoderms starfish Sea fan (crinoid) Brittle star Sand dollar
Sea cucumber

29 Vertebrate Groups

30 Vertebrata More complex animals
Most have a backbone made up of individual bones called vertebrae From simplest to most complex, the phylum includes: fish, amphibians, reptiles, birds, and mammals

31 Vertebrate Backbone

32 Vertebrata Vertebrates have endoskeletons (internal)
Some vertebrates have skeletons of cartilage (sharks, rays, and skates) Other vertebrates have skeletons of bone and cartilage (reptiles, birds, & mammals)

33 Bone & Cartilage in Fetus

34 Fish lancelet ray damselfish anglerfish

35 Amphibia salamander toad frog newt

36 Reptilia Turtle Snake Lizard Alligator

37 Birds - Aves hummingbird ostrich lovebirds

38 Mammalia

39 Body Areas

40 Surfaces Dorsal – back or upper surface
Ventral – belly or lower surface Anterior – head or front end Posterior – tail or hind end opposite the head Oral surface (echinoderms) – is where the mouth is located (underside) Aboral surface (echinoderms) – is opposite the mouth (top side)

41 Surfaces (Most Animals)

42 Surfaces (Echinoderms)

43 Symmetry

44 Body Symmetry

45 Body Symmetry Symmetry is the arrangement of body parts around a central plane or axis Asymmetry occurs when the body can’t be divided into similar sections (sponges)

46 Body Symmetry Radial symmetry occurs when body parts are arranged around a central point like spokes on a wheel (echinoderms) Most animals with radial symmetry are sessile (attached) or sedentary (move very little)


48 Body Symmetry Bilateral symmetry occurs when animals can be divided into equal halves along a single plane Organisms will have right and left sides that are mirror images of each other More complex type of symmetry

49 Body Symmetry Animals with bilateral symmetry are usually motile
Animals have an anterior and posterior ends Show cephalization (concentration of sensory organs on the head or anterior end)


51 Segmentation

52 Segmentation Occurs whenever animal bodies are divided into repeating units or segments Found in more complex animals Earthworms show external segmentation Humans show internal segmentation (backbone) Segments may fuse (cephalothorax)

53 Segmentation cephalothorax

54 Tissues

55 Tissue Development Zygote (fertilized egg) undergoes rapid cell divisions called cleavage Forms a hollow ball of cells called the blastula

56 Blastula The blastocoel is the center cavity of the blastula with 1 germ layer (blastoderm)

57 Tissue Development The blastula INVAGINATES (folds inward at one point) Called Gastrulation The opening is called the blastopore The center is the primitive gut or Archenteron Archenteron blastopore

58 Tissue Development Blastopore may become the mouth (Protostome) or anus (Deuterostome) Protostomes (mollusks, arthropods, & annelids) Deuterostomes (echinoderms & vertebrates) Some animals form a middle germ layer called mesoderm

59 Embryonic Development

60 Germ Layers Form tissues, organs, & systems NOT present in sponges
Ectoderm (outer) – forms skin, nerves, sense organs Endoderm (inner) – forms liver and lungs Mesoderm (middle) – forms muscles & other systems

61 Body Layers Sponges have NO tissues or organs, only specialized cells
Cnidarians like jellyfish & coral have only two body layers & one body opening (mouth/anus) into gastrovascular cavity Cnidarians have outer epidermis & inner gastrodermis with jelly-like mesoglea between the layers


63 Body Layers All worms, mollusks, arthropods, echinoderms, and vertebrates have three cell layers Ectoderm Endoderm mesoderm

64 Embryonic Cleavage

65 Cleavage Cleavage – rapid mitosis (cell division) of zygote
Radial Cleavage – cells divide parallel or perpendicular to axis to each other

66 Cleavage Spiral Cleavage – cellular divisions occur diagonally, in a twisting pattern


68 Stages of Development

69 Larval Forms Animals with Indirect development
Go through immature (larval) forms Larva does NOT resemble adult Cnidarian (jellyfish, coral, & sea anemone) larva called Planula

70 Larval Forms Mollusk (squid & octopus) larva called trochophore
Echinoderm (starfish) larva is called Dipleurula

71 Metamorphosis Usually found in arthropods
May be complete or incomplete Incomplete Metamorphosis: egg nymph adult Complete Metamorphosis: egg larva pupa adult


73 Body Cavities

74 Coelom - Body Cavity Internal body cavity fully lined with mesoderm
Body organs suspended in this cavity

75 Coelom - Body Cavity Acoelomate animals have solid bodies filled with cells Acoelomate animals include sponges, cnidarians, & flatworms

76 Coelom - Body Cavity Pseudocoelomate animals (roundworms) have a functional body cavity NOT fully lined with mesoderm

77 Animal Systems

78 Support Systems Spongin & spicules (sponges) Limestone cases (corals)
Exoskeletons of Chitin (arthropods) Must be shed or molted to grow Inner Calcium plates or Test (echinoderms) Bone/cartilage endoskeleton (vertebrates)

79 Digestive Systems All animals are ingestive heterotrophs
Choanocytes (specialized cells) capture & digest food for sponges Gastrovascular cavity with one opening in cnidarians and flatworms for food to enter & leave; called two-way digestive system

80 Two-Way Digestion

81 Digestive Systems Animals with a one-way digestive system have a mouth and an anus Food enters the mouth, continues in one direction through the digestive tract, and wastes leave through the anus Includes annelids, arthropods, & vertebrates

82 One-Way Digestion Mouth anus

83 Circulatory Systems Transports oxygen & nutrients to cells
Carries away wastes & carbon dioxide from cells Sponges, cnidarians, & flatworms do NOT have circulatory systems

84 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)

85 Open Circulation Closed Circulation



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