Chapter 32: Animal Diversity

By: Group D; Daniel Cazares del Castillo, Fabian Abarca, Justin Cruz, Jayce Frank, William Hoover, And Alberto Rodriguez

General Features of Animals• Heterotrophy: all animals are heterotrophs. They obtain energy

and organic molecules by ingesting other organisms.

• Multicellularity: all animals are multicellular, many have complex bodies like the jellyfish.

• No Cell Walls: animal cells differ from those of other multicellular organisms: they lack rigid cell walls and are usually quite flexible.

• Active movement: animals move more rapidly and in more complex ways than members of other kingdoms-this ability is perhaps their most striking characteristic, one directly related to the flexibility of their cells and the evolution of nerve and muscle

tissues.

General Features of Animals• Diversity in Form- Animals range in size and shape. Most of

the animals on Earth are invertebrates. The others are vertebrates.

• Diversity in Habitat- The animal kingdom is divided into 35-40 phyla. Most of them occur in the sea. Only a couple of them live in freshwater and on land.

• Sexual Reproduction- Most animals sexually reproduce. Only some species are incapable of sexual reproduction.

• Embryonic Development- an animal zygote first undergoes a series of mitotic divisions, called cleavage, and like this dividing frog's egg, that produces a ball of cells. the blastula. in most animals, the blastula folds inward at one point to fomr a hollow sac with one opening at one end called the blastopore. an embryo at this stge is called a gastrula.

• Tissues-the cells of all animals except spones are organized into structural and functional units called tissues.

Evolution of the Animal Body PlanFive key innovations can be noted in

animal evolution1.The evolution of symmetry2.The evolution of tissues, allowing

specialized structures and functions3.The evolution of a body cavity4.The evolution of various patterns of

embryonic development5.The evolution of segmentation, or

repeated body units

Evolution of Animal Body Plan: Symmetry• Most animals exhibit radial or bilateral

symmetry.

• Radial symmetry is arranged in a way that a longitude plane passes through the central axis

• Bilateral Symmetry is when the body has right and left halves that are mirror images of each other

Evolution of Animal Body Plan: Specialized Structures and Functions• During embryonic development, cells

specialize to carry out particular functions

• In all animals, except for sponges, the process is irreversible

Evolution of Animal Body Plan: Body Cavity• In the process of embryonic

development, the cells of animals of most groups organize into three layers (called germ layers): an outer ECTODERM, an inner ENDODERM, and an intermediate MESODERM.

Evolution of Animal Body Plan: Embryonic Development

• Bilaterians have two main types of development

• It begins with mitotic cell divisions (called cleavages) of the egg that lead to the formation of a hollow ball of cells, which subsequently indents to form a two-layered ball

• Protostomes, "first mouth,"

• Deuterostomes, "second mouth"

Evolution of Animal Body Plan: Segmentation• Segmented animals consists of a series

of linearly arrayed compartments that typically look alike, at least in early development, but that may have specialized functions.

• Two advantages result from early embryonic segmentationo In highly segmental animals, each segment

may develop a more or less complete set of adult oragn systems, damage to any one segment need not be fatal because other segments duplicate the damaged segment's functions

Evolution of Animal Body Plan: Segmentation (Continued)

• Locomotion is more efficient when individual segments can move semi-independently. Because partitions isolate the segments, each can contract or expand autonomously. Therefore, a long body can move in ways that are often quite complex.

Vocab• Radial Symmetry- arranged in a way that a longitude plane passes through the

central axis

• bilateral symmetry-the body has right and left halves that are mirror images of each other

• cephalization- concentration of nervous tissue at the anterior end

• ectoderm- the outer layer of the one of three germ layers

• endoderm- the inner layer of three germ layers

• mesoderm- the intermediate layer

• pseudocoelom- develops embryologically between mesoderm and endoderm

• coelom- a cavity thats develops entirely within the mesoderm

• open circulaory system- blood passes from vessels into sinuses

• closed circulatory system- entirely confined to blood vessels

• archenteron- means primitive gut

• protostomes-includes flatworms, nematodes, mollusks, annelids and arthropod

• spiral cleavage- line drawn through a sequence of dividing cells spirals outward from the polar axis

• colonial flagellate hypothesis- first proposed by Ernst Haeckel in 1874 is that metazones descended from colonial protists

True or False

T/F Heterotrophy applies to all animalsT/F Animals have cell wallsT/F Protostomes are the "Second Mouth"T/F Once animals specialize during their

embryonic development, the new function is irreversible (in all animals)

T/F There are five key innovations that can be noted in animal evolution

Multiple Choice

1. What kinds of symmetry do most animals exhibita. asymmetrical and radialb. bilateral and asymmetricalc. asymmetrical and symmetricald. radial and bilaterale. all of the abovef. none of the above