Chapter 9: Architectural Pattern of an Animal Metazoans

32 Phyla of multicellular animals Survivors of 100 phyla from the Cambrian explosion 600 million years ago.

Heterotrophy Cannot make own food Filter feed in ocean or find food

Mobility Muscle cells Swim, crawl, walk, run and fly Some sessile(do not move)                                      

Multicellularity Daphnia to large whale More than one cell

Organization and Complexity Metazoa or multicellular animals evolved greater complexity by combining cell into larger units Cell – tissue – organs – organ systems Parenchyma – main functional cells Stroma – supportive tissues

Segmentation Also called metamerism Common feature of animals Serial repetition of similar body segments along the longitudinal axis of body (parts repeat) Each segment is called a metamere or somite.

Allows for more mobility and complexity of structure and function Examples include annelids, chordates and arthropods ( Worms, vertebrates and insects)

Diploidy Adults have 2 copies of each chromosome One from mother and one from father

Sexual reproduction Gametes from 2 separate parents Can also see asexual reproduction in the animal kingdom – budding – all genetic information comes from on parent

No cell wall - mobility Eukaryotic – nucleus and other membrane bound organelles

Blastula Formation Zygote forms blastula Hollow ball of cells Develop into 3 distinct layers Ectoderm/endoderm/mesoderm These layers give rise to all other tissues/organs

Zygote - Gastrula Found in all animals but sponges One cell – 8 cells – blastula – layers Process is called cleavage Takes 3 hours to reach blastula Second process the blastula begins to collapse inward while cells move to position - gastrulation

Cell begin to vary in size and form the 3 primary tissues Now at embryo stage Evidence of common ancestor

Blastopore Opening to the gut where the inward bending begins First opening that forms in the gastrula

During embryonic development germ layers become differentiated into four tissues. Epithelial Connective Muscular Nervous

The development of an animal embryo follows one of two different patterns Protostome – The blastopore develops into mouth-most invertebrates Deuterostome-The blastopore develops into the anus – Echinoderms and Chordates

Animal Body Plans Limited by ancestral history. Shaped by habitat and way of life.

Animal Symmetry Arrangement of body parts with reference to same axis of body. Most animals have symmetry. Sponges do not. Asymmetrical

Asymmetry Without symmetry

Spherical Symmetry Any plane passing through the center divides the body into mirrored halves. Protozoa

Radial Symmetry Divided into similar halves by more than two planes passing through one main axis. Tubular, vase or bowl shape. Some sponges, Hydras, Jellyfish

Biradial Symmetry Some parts are paired rather than radial.

Echinoderms Larvae are Bilateral Become secondarily radial as adults.

Bilateral Symmetry Divided along a sagital plane into two mirrored portions-right and left halves Better fitted for directional movement-forward Associated with cephalization

Sagittal Transverse Frontal Draw your own squirrel and label now

Animal Body Regions Anterior – head end Posterior – tail end Dorsal – back side Ventral – front or belly side Medial – midline of the body Lateral – the side of body

Distal – farther from the middle of the body Proximal – parts near a reference point Pectoral – chest region Pelvic – hip region or area supported by hind legs

Body Cavities Bilateral animals can be grouped according to their body cavity type or lack of body cavity. Coelom – in more complex animals the main body cavity. A fluid filled space that surrounds the gut.

Provides a “tube within a tube” arrangement. Allows body flexibility. Provides a space for visceral organs or internal organs.

Greater size and complexity – more cells exposed to surface exchange. Hydrostatic skeleton in many animals. Worms

Coelom forms differently in protostomes and deuterostomes Some inverts or protostomes lack a coelom

Cephalization Differentiation of a head or head region. Bilaterally symmetrical animals. Most efficient position for sensing the environmental and responding to it.

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