1. Zoology – the study of animals.  There are 1.5 million+ animals (estimates as high as 3 million undescribed).  Classified into 35 current Phylums35 current Phylums  Phylum Arthropoda = 1.2 million+ named species.  Mammals represent only about 5, 000 named species!

2. Zoology Disciplines  Comparative Anatomy – the study of structures and functions of various animal groups.  Taxonomy – the science of finding, describing, and classifying animals.  Entomology – the study of insects.  Ichthyology – the study of fish  Herpetology – the study of reptiles and amphibians.  Ethology – the study of animal behavior.  Malacology – the study of molluscs.  Myrmecology – the study of ants.  Helminthology – the study of worms

4. What is an Animal?  Petunia is a plant and  Wolf spider is an animal.

5. What is an Animal?  Coral  sessile (“rooted”?)  stem, branches,  greenish.  Resembles plant;  but this IS an animal! Why?

6. What IS an Animal?  Definition of "Animal"  Multicellular (so are plants, fungi)  Eukaryotic (so are plants, fungi)  Diploid (usually) (so are plants, fungi)  Meiosis produces gametes called sperm and egg  Sperm, egg are the only haploid cells  Heterotrophic by ingestion  Cells lack cell walls.

7. What IS an Animal? Basic structure (not definition) = Tube-in-tube  Body wall = outer tube  gut (GI tract) = inside tube  mouth  anus

8. Embryological Development in Animals  Every animal begins as ZYGOTE  How do animals develop tube-in-tube body form?  Important in understanding relationships, classification of Phyla.

9. Three fundamental processes: 1. Morphogenesis  (morph- = shape, + genesis = origin)  Origin of shape, form 2. Differentiation  Process of cells becoming different, and specializing for different functions 3. Growth  Increase in size, requires input of matter, food

10. Embryology Sequence of Events: 1. Fertilization 2. Cleavage 3.Gastrulation 4.Organogenesis

11. 1. Fertilization  Gametes join in fertilization  gametes are produced (gametogenesis) through meiosis  What process produces every other cell in the human body?  MITOSIS

12. Let the Division Begin!

13. 2. Cleavage  Cleavage is a series of rapid mitotic divisions (without cell growth)  The two-celled zygote divides repeatedly until a ball of 32 cells is formed  This is the morula - 32 cells 

14.  Continued divisions make the hollow blastula  These few cells are pluripotent (have the potential to become ANY of the 220 types of cells in the human body).  These are embryonic stem cells

15. 3. Gastrulation Gastrulation = formation of a gut;  Major MORPHOGENIC event !!!  At the end of the cleavage stage, cells making up the blastula move about and surface proteins help cells recognize each other  Location of cells after GASTRULATION determines further development  The gastrula is formed, which can consists of 3 “germ layers” 1. Endoderm “inside skin” 2. Mesoderm “middle skin” 3. Ectoderm “outside skin”  Will yield Archenteron in primitive animals  “ancient gut” = first formation of "inside tube."

16. Development in Classification Tissues -collections of specialized cells working together and isolated from other tissues by membranous layers. (germ layers) Diploblastic Animals – Have two germ layers, ectoderm and endoderm. (Jellyfish) Triploblastic Animals – Have three germ layers, ecto-, meso-, and endoderm. (Vertebrates)

17. Gastrulation

18. Zygote Cleavage Eight-cell stage Cleavage Blastula Cross section of blastula Blastocoel Gastrula Gastrulation Endoderm Ectoderm Blastopore Early embryonic development in animals In most animals, cleavage results in the formation of a multicellular stage called a blastula. The blastula of many animals is a hollow ball of cells. 3 The endoderm of the archenteron de- velops into the tissue lining the animal’s digestive tract. 6 The blind pouch formed by gastru- lation, called the archenteron, opens to the outside via the blastopore. 5 Most animals also undergo gastrulation, a rearrangement of the embryo in which one end of the embryo folds inward, expands, and eventually fills the blastocoel, producing layers of embryonic tissues: the ectoderm (outer layer) and the endoderm (inner layer). 4 Only one cleavage stage–the eight-cell embryo–is shown here. 2 The zygote of an animal undergoes a succession of mitotic cell divisions called cleavage. 1

19. Body Cavity Development Body Cavity (Coelom) – is a fluid-filled space separating digestive tract from outer body wall.  Cushions internal organs, allows internal organs to move independently of the outer body wall, hydroskeleton in some animals (earthworm).  Animals with no coelom - acoelomates  Animals with a true coelom – coelomates – coelom forms from mesoderm to become mesenteries and suspend internal organs.  Animals form a cavity from the blastocoel - pseudocoelomates

20. Organisms without body cavities Are considered acoelomates Body covering (from ectoderm) Tissue- filled region (from mesoderm) Digestive tract (from endoderm) Acoelomate. Acoelomates such as flatworms lack a body cavity between the digestive tract and outer body wall.

21. A pseudocoelom a body cavity derived from the blastocoel, rather than from mesoderm Pseudocoelom Muscle layer (from mesoderm) Body covering (from ectoderm) Digestive tract (from ectoderm) Pseudocoelomates such as nematodes have a body cavity only partially lined by tissue derived from mesoderm.

22. A true body cavity is called a coelom and is derived from mesoderm Coelom Body covering (from ectoderm) Digestive tract (from endoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) Coelomate. Coelomates such as annelids have a true coelom, a body cavity completely lined by tissue derived from mesoderm.

24. Coelomates will further branch into either a Protostome or Deuterostome Based on certain features seen in early development  3 Characteristics Determine the Group:  Cleavage Pattern (Cell Division)  Coelom Formation  Fate of the Blastopore

25. Cleavage Pattern (Cell Division) In protostome development Cleavage is spiral (mitotic spindles at diagonals to embryo axis) and determinate (cells fixed on a developmental pathway) In deuterostome development Cleavage is radial (spindles parallel and perpendicular) and indeterminate (cells can adjust) Protostome development (examples: molluscs, annelids, arthropods) Deuterostome development (examples: echinoderms, chordates) Eight-cell stage Spiral and determinate Radial and indeterminate (a) Cleavage. In general, protostome development begins with spiral, determinate cleavage. Deuterostome development is characterized by radial, indeterminate cleavage.

26. Coelom Formation  In protostome development, the solid mass of mesoderm cells split to form the coelom  In deuterostome development, mesoderm buds from endoderm

28. Fate of the Blastopore  In protostome development the blastopore becomes the mouth  In deuterostome development the blastopore becomes the anus Anus Mouth Mouth develops from blastopore Anus develops from blastopore Digestive tube

29. 4. Organogenesis Organogenesis Purpose:  Formation of organs from three germ layers  Differentiation & continued Morphogenesis 1. Ectoderm will form the following:  Epidermis  Lining of mouth & rectum  Cornea of eye  Lens of eye  Nervous system  Thin linings of gut & branches  lining of excretory ducts, bladder  Lining of lungs, trachea  Lining of reproductive ducts, uterus, vas deferens  liver  pancreas

30. Organogenesis 2. Mesoderm will form the following:  Skeleton,  Muscles (skeletal, smooth, cardiac)  Dermis of skin  Heart, blood, blood vessels  Kidneys,  Ovaries/testes, etc.

31. Organogenesis 3.Ectoderm forms the following:  Epidermis  How Nervous system gets inside a. Dorsal surface of embryo forms Neural plate b. Plate sinks inward forming Neural groove c. Edges of groove fuse to separate Neural tube from epidermis

32. Extraembryonic Membranes  These membranes develop from the germ layers, but are NOT part of the embryo (they are lost at birth)  They lie outside of the embryo & provide protection and nourishment  Four exist in terrestrial vertebrates:  Chorion, amnion, allantois (stores nitrogenous waste in reptiles), & yolk sac (not found in humans, but yolk aids in formation of RBC

33. Human Development  The gestation period lasts 266 days from fertilization to birth  Organogenesis (development of the organs and organ systems) begins with the nervous system  Think on this: Do all animals have the same gestation period?

34. Patterns of Organization 4 Ways of Animal Organization: Symmetry (Asymmetry, Radial, Bilateral) Tissue Organization (Diploblastic, Triploblastic) Body Cavity Development (Acoelomate, Pseudocoelomate, Coelomate) Embryological Development (Protostome and Deuterostome)

35. Symmetry Asymmetry – arrangement of body parts without a central axis or point (sponges). – No complex sensory or locomotion functions. Radial Symmetry – arrangement of body parts such that a single plane passing through the oral-aboral axis divides the animal into mirror images (sea anemones, starfish). – No blind side. Bilateral Symmetry - arrangement of body parts such that a single plane passing through the longitudinal axis divides the animal into right and left mirror images (vertebrates). – Cephalization – form distinct head to analyze the environment as they move through it.

36. Some animals have radial symmetry like in a flower pot Radial symmetry. The parts of a radial animal, such as a sea anemone (phylum Cnidaria), radiate from the center. Any imaginary slice through the central axis divides the animal into mirror images.

37. Some animals exhibit bilateral symmetry or two-sided symmetry Bilateral symmetry. A bilateral animal, such as a lobster (phylum Arthropoda), has a left side and a right side. Only one imaginary cut divides the animal into mirror-image halves.

38. What Kind of Symmetry Do I Have?

40. What Kind of Symmetry Do We Have?

41. Anatomical Planes and Directions 7-9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 7.9 Sagittal plane Bilateral Symmetry

42. Directional Terms 1. Anterior and Posterior a. Anterior refers to being towards the front b. Posterior refers to being towards the back 2.Dorsal and Ventral a. Dorsal refers to the upper back region b. Ventral refers to the bottom region, relating to the underside

43. Directional Terms 3. Superior and Inferior a. Superior refers to being above b. Inferior refers to being below

44. Directional Terms 4.Proximal and Distal a. Proximal refers to being closer to a point of attachment or the trunk b. Distal refers to being farther away from a point of attachment or the trun k

45. Directional Terms 5. Medial and Lateral a. Medial refers to being closer to a vertical midline b. Lateral refers to being closer to the sides with relation to the midline

46. Directional Terms 6. Superficial and Deep a. Superficial refers to being closer to the surface b. Deep refers to being more internal 7.Plantar Refers to the sole of the foot

47. Body Planes (Sections) The body can be sectioned in three different planes. Each one gives a different perspective.

48. Body Planes (Sections) 1.Sagittal Section – lengthwise (vertical) cut that divides the body into right & left halves 2.Transverse Section – horizontal cut that divides the body into inferior and superior portions 3.Coronal Section – vertical cut that divides the body into anterior & posterior portions

49. Hot Dog Dissection Objectives:  The student will become familiar with directional terminology.  The student will become familiar with body section cuts. Procedure:  Identify the superior and inferior position on your specimen. Label these regions on your paper plate.  Identify the anterior and posterior position on your specimen.  Using a permanent marker, draw a sagittal body plane on the anterior portion of your specimen. Specimen must be dry for this!  Discuss with your partner how medial & lateral relate to this sagittal plane.  Make a medial superficial incision on the posterior side from the superior to the inferior position.  Now make a superficial transverse incision on the anterior side proximal to the arms.  On the inferior, anterior tip, remove a 1-inch section. Use this section to cut a coronal section.  Label the plantar region.  Using the examples in your notes, relate the body terminology to the relative position terminology.