GEN BIO II - EXAM 3, CH 27

characteristics of the animal kingdom

multicellular, eukaryotic, heterotrophic, body plan based on development

9 phyla (2 for this exam)

Porifera, Cnidaria

Porifera

sponges

Cnidaria

jellyfish, sea anemones, coral

vertebrates

animals with a segmented backbone

invertebrates

animals without a segmented backbone

body plan differences

comes from mutations in Hox genes

Hox genes

tell the embryonic cells which body part to become

groupings

animals are grouped on 3 criteria: body plan symmetry, tissues, and developmental patterns

bilateral symmetry (criteria 1)

can be divided into 2 mirror-image halves

radial symmetry (criteria 1)

many lines of symmetry through a central location (environment is important)

three tissue layers

endoderm, ectoderm, mesoderm

diploblastic animals (radial) [criteria 2]

have endoderm and ectoderm

triploblastic animals (bilateral) [criteria 2]

have endoderm, mesoderm, and ectoderm

ectoderm

the germ layer covering the embryo surface, and forms the skin

endoderm

the innermost germ layer, and forms the respiratory and digestive systems

mesoderm

middle layer, and forms the reproductive and circulatory systems, and muscles

developmental patterns (criteria 3)

animals are divided into 2 groups: protostomes and deuterostomes

protostomes

mouth forms first, then the anus + cleav. is spiral and determinate

deuterostomes

anus forms first, then the mouth + cleav. is radian and indeterminate