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!

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

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

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.

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

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.

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

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

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

Let the Division Begin!

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 

3. Gastrulation Gastrulation = formation of a gut;  Major MORPHOGENIC event !!!  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”

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)

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).

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.

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.

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.

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

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

Organogenesis 3.Ectoderm forms the following:  Epidermis  How Nervous system gets inside

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?

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)

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.

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.

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.

What Kind of Symmetry Do I Have?

What Kind of Symmetry Do We Have?

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

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

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

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

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

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

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

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