Kingdom Animalia Multicellular, heterotrophic eukaryotes Capable of controlled locomotion Unique tissue: nervous and muscle 35 phyla > 1 million described species 3 - 30 million estimated number of species (See Table 32.1 for a more complete list of common characteristics)

Arose from a colonial flagellated protistan Animal Origins Arose from a colonial flagellated protistan Colonial Theory (Haeckel) Coordination and cooperation between cells Common features between animals and protists

Proterospongia haeckeli An extant colonial choanoflagellate Note cellular specialization - flagellated cells - amoeboid cells

Supporting Evidence for Colonial Theory Flagellated sperm cells throughout Metazoa Flagellated body cells among lower Metazoa True eggs and sperm in phytoflagellates Phytoflagellates and colonial organization

Animal Origins Despite their morphological diversity, animals are monophyletic

Supporting Evidence Flagellated sperm Early stages of embryology Common themes in animal body plans Despite their morphological diversity, animals are monophyletic

Key Features in Animal Diversity Level of organization Symmetry Body plan Embryological development Understanding differences and patterns evident in animal kingdom = understanding of animal macroevolution

Levels of Organization Ancestral form had some specialized cells and some cooperation between cells Subkingdom Parazoa, which includes the sponges, lack tissues Evolution of tissues was next step in animal evolution Compartmentalization into specialized “regions” was the next step

Organ Systems Organs Tissues Specialized Cells With increasing specialization, eventually see regionalization Organs Tissues Specialized Cells

Fig. 32.8

Symmetry How many planes can a body be divided into along its long axis and still get mirror images?

Animals that move in one direction have bilateral symmetry; can be divided into similar halves on only one plane. The plane runs from the anterior end to the posterior end (tail). A plane at right angle to the midline divides animals into dorsal and ventral (belly) surfaces.

Radial symmetry – typically in sessile animals (all or part of their life cycle) Bilateral symmetry is associated with cephalization

Fig. 32.8

Body Plans Attributes considered for all animals Presence or absence of different tissue types Type of symmetry Presence or absence of a true body cavity

Body Plans – Bilateral Animals All animals based on one of three body plans Different body plans provide different adaptive advantages Apparent trend - increased potential body size Body cavity is area between body wall and internal organs

Body Plans – Bilateral Animals Embryological development of tissues Ectoderm Mesoderm Endoderm

Fig. 32.4c Acoelomate

Fig. 32.4b Pseudocoelomate

Fig. 32.4a Eucoelomate

Acoelomate - cavity filled with tissue Pseudocoelomate - cavity filled with liquid Coelomate - cavity filled with fluid and organs supported by membranes

Fig. 32.8

Embryology and Developmental Biology

All animals go through the same initial stages of embryonic development (see Fig. 32.3)

Protostomes (“mouth first”): the blastopore develops into the mouth. Deuterostomes (“mouth second”): the blastopore develops into the anus; the mouth develops later.

Embryological Development Protostomes spiral cleavage determinate cleavage mesoderm develops by cell sloughing Deuterostomes radial cleavage indeterminate cleavage mesoderm develops from tissue folds

Fig. 32.5

Fig. 32.8

Cambrian Explosion All animal phyla except one appeared in a geological instant 545 mya Some groups disappeared? Why such diversity is so short a period of time (20 million years)?

Molecular View of Animal Phylogeny Genomes and Proteomes – Hox genes and patterning of body axis in vertebrates Feature Investigation – Taxonomic relationship of arthropods

See Table 32.2 Will be helpful for Chapters 33-34 For second Animal Diversity lab

Fig. 32.8