Form and Function: Animals

Asymmetrical

Animals, structures or organs which cannot be divided into similar halves by any plane

Bilateral

Animals, structures or organs which can be divided into two equal and similar halves by a single plane

Radial

Having similar parts arranged concentrically around a longitudinal axis, typically the oral-aboral axis. Can be divided into identical pie-shaped pieces along their radial axes. If an animal can be divided into eight identical wedges, it is called octaradial. Animals divisible by five are pentaradial and so on

Anterior

Nearer the front or that which is foremost in locomotion. The head end in quadrupeds and ventral surface in bipeds. Opposite of posterior

Cephalic

Pertaining to the head. Opposite of caudal. Also called cranial

Posterior

Nearer the back. Tail or hind end in quadrupeds and the dorsal surface in bipeds. Opposite of anterior

Caudal

Pertaining to the tail or posterior end of the body. Opposite of cephalic

Dorsal

Toward or pertaining to the upper surface. Opposite of ventral

Ventral

Toward or pertaining to the lower surface. Opposite of dorsal

Medial

Pertaining to the middle part of the body. Contrasted with lateral

Lateral

The side of the body. Contrasted with median. In a bilateral organism, the sides of the body are referred to as right or left. Note that this refers to the organism's right and left sides, not your own

Proximal

Nearer the point of attachment, for example, the shoulder is the proximal end of the arm. Opposite of distal

Distal

Away from the point of attachment. Opposite of proximal

Longitudinal

Lengthwise; parallel to the long axis of the body.

Circular

Around the long axis of the body in the transverse plane

Oral

Pertaining to the mouth. Area around the mouth. In radially symmetric animals, the surface bearing the mouth

Aboral

Pertaining to the region not associated with the mouth. Opposite of oral. A term used mainly to describe radially symmetric animals.

Saggital Plane

Pertaining to the median vertical longitudinal plane of the body. It divides the body into symmetrical right and left halves. Also called midsagittal. A plane parallel to the midsagittal is a parasagittal plane

Frontal Plane

A plane parallel to the ventral or dorsal surface of any bilaterally symmetrical animal; at right angles to the sagittal plane

Transverse Plane

Any plane at right angles to the sagittal and frontal planes. A cross section

Anterior-Posterior Axis

An axis extending from the anterior to the posterior end

Dorsal-Ventral Axis

An axis extending from the dorsal to the ventral surface

Oral-Aboral Axis

An axis extending from the oral to the aboral surface in radially symmetric animals

Radial Axis

An axis extending from the centre of a radially symmetric animal to the periphery

Metazoans

Multicellular animals

34

___ phyla of multicellular animals

Cambrian Explosion

basic body plans have not changed since the ___________

Cambrian Explosion

Most phyla appeared during this period

Protozoa

single celled eukaryotes (protoplasmic)

• Complete organism within one cell (Protists)

• E.g., Paramecium

Metazoa

multicellular animals with greater complexity

• Individual cells cannot survive on their own

• Cells are specialized for certain functions

• Parenchyma: functional cells

• Stroma: support cells

Parenchyma

Functional cells

Stoma

Support cells

Symmetry

refers to the correspondence of size and shape on opposite sides of a plane

Bilateral

Most animals with a head

Spherical

Any plane passing through the center divides a body into equivalent, or mirrored, halves. Rare in animals

Zygote

Fertilized egg, single cell

Blastula

Cluster of cells

Gastrula

2-3 layered embryo; germ layers

Ectoderm

Forms the exoskeleton

Mesoderm

Develops into organs

Endoderm

Forms the inner lining of organs

Diploblastic

• Only 2 germ layers: endoderm and ectoderm

• Cnidarians (sea anemones, e.g.), flatworms

Triploblastic

• 3 germ layers: mesoderm (develops from the endoderm)

• Organs, organ systems

• Most animals

Pseudocoelomate Body

Mesoderm lines outer edge of blastocoel

Acoelomate Body

Mesoderm completely fills blastocoel

Coelomate Body

Coelomic cavity forms inside mesoderm

3

Triploblastic animals are further classified into ____ types

Extracellular Components

• body fluids (intracellular and extracellular)

• extracellular structural elements

Cellular Components

• tissue

Intracellular Fluids

within the individual cells

Extracellular Fluids

between cells or within cavities. In animals with a closed circulatory system:

• Blood plasma

• Interstitial fluid – between cells

Structural Components

• Connective tissue

• Cartilage

• Bone

• Cuticle

Epithelial Tissue

forms the covering on all internal and external surfaces of the body, lines body cavities and hollow organs and is the major tissue in glands

Connective Tissue

diverse body tissue that connects, supports, protects, and binds other tissues and organs, forming the body's framework

Nervous Tissue

the main tissue of the nervous system (brain, spinal cord, nerves) responsible for controlling body functions by rapidly transmitting electrical and chemical signals, coordinating movement, sensations, and thought

Sponges

Have zero germ layers

No

Can diploblastic animals have organs?

Pseudocoelomate, Acoelomate, Coelomate

3 types of triploblastic animals

Grade of organization, symmetry, germ layers and body cavities

Animal phyla are distinguished from each other by their body plans; this includes:

Protoplasmic, cellular, cell-tissue, tissue-organ, organ-system

The five major grades of organization are…

Protoplasmic

Characterizes unicellular organisms. All life functions are confined within the boundaries of a single cell, the fundamental unit of life. Within a cell, protoplasm is differentiated into organelles capable of performing specialized functions

Cellular

An aggregation of cells that are functionally differentiated. A division of labour is evident, so that some cells are concerned with, for example, reproduction, and others with nutrition.

Cell-Tissue

An aggregation of similar cells into definite patterns or layers and organized to perform a common function, to form tissue

Tissue-Organ

An aggregation of tissues that forms organs in a further step in complexity. Organs are usually composed of more than one kind of tissue and have a more specialized function than tissues

Organ-System

Organs working together to perform some function, producing the highest level of organization - an organ system. Systems are associated with basic body functions such as circulation, respiration, and digestion

Eumetazoans

Animals at or beyond the cell-tissue grade of organization

11

______ different kinds of organ systems are described in animals

Bilateria

Bilateral animals form a monophyletic group of phyla called the…

Pectoral

In vertebrates _______ denotes the chest region or area associated with the anterior pair of appendages

Pelvic

In vertebrates, _______ denotes the hip region associated with the posterior pair of appendages

Blastopore

Typically becomes the adult mouth or anus

Segmentation

• also called metamerism

• Serial repetition of similar body segments along the longitudinal axis of the body

Metamere

Each segment of segmentation is called a _______, or somite

Segmentation

Permits greater body mobility and complexity of structure and function

Interstitial Fluid

Also called tissue fluid, occupies the space surrounding cells

Histology

The study of tissues

Epithelial, nervous, connective, muscular

4 types of tissue

Epithelium

A sheet of cells that covers an internal or external surface