Animals Heterotrophic Multicellular Move at some point No

Animals Heterotrophic Multi-cellular Move at some point No cell walls Mostly reproduce sexually Rapidly respond to external stimuli

An Evolutionary Tree of Some Major Animal Phyla Fig. 23 -1

Most animals have tissues Tissues are groups of similar cells that carry out a specific function (e. g. , muscle) Sponges are the only modern-day animals that lack tissues

Symmetry Animals with tissues exhibit either radial or bilateral symmetry Bilateral symmetry Radial symmetry Asymmetry http: //www. misterteacher. com/orange%20 and%20 black%20 butterfly. jpg http: //www. hope. edu/academic/art/past/Va nder. Burgh/mapleave. rose 2. jpg http: //daphne. palomar. edu/design/asymm/j d 01 asym. jpg

Symmetry Radial symmetrical animals have two embryonic tissue (germ) layers �Ectoderm, which is an outer layer that covers the body, lines its inner cavities, and forms the nervous system �Endoderm, which is an inner layer that lines most hollow organs Bilaterally symmetrical animals have three embryonic tissue (germ) layers �A layer of mesoderm between the ectoderm and endoderm forms muscles, and the circulatory and skeletal systems

Bilateral Symmetry Bilaterally symmetrical animals have heads Exhibit cephalization, the concentration of sensory organs and a brain in a well-defined head, with definite anterior (head) and posterior (which may feature a tail) regions

Body Symmetry and Cephalization central axis anterior plane of symmetry posterior (a) Radial symmetry (b) Bilateral symmetry Fig. 23 -2

Bilateral Symmetry Most bilateral animals have body cavities Fluid-filled cavities between the digestive tube and the outer body wall Many functions �Can act as a skeleton, providing support for the body and a framework against which muscles can act �Can form a protective buffer between the internal organs and the outside world �Can allow organs to move independently of the body wall

Major Animal Phyla Animals probably originated from ancestral colonial protists Present day biologists recognize about 27 phyla of animals Most animals are invertebrates Less than 3% of all known animals are vertebrates

Animals Can be invertebrates or vertebrates What’s the difference? Invertebrates vs. * No vertebral column * Often have exoskeletons Vertebrates * Vertebral column * Endoskeletons

Invertebrates http: //www. sunrise-divers. com/photos/day_trip/photos/nudibranch. jpg

PHYLUM PORIFERA THE SPONGES http: //www. richard-seaman. com/Underwater/Belize/Still. Lifes/Tube. Sponges. Three. Orange. jpg

Cnidaria http: //www. biology 4 kids. com/misc/photo s/cnidaria 1. jpg

Cnidaria – Polyp body form http: //www. sydneyaquarium. com. au/Downloads/INT/Wallpape r_1024 x 768_Waratah. Anemone. jpg

Platyhelminthes - flatworms Planaria http: //www. luc. edu/faculty/jreymon/b iolab/planaria. jpg

Marine Flatworms http: //members. aol. com/uwphotohi/Images/flatworm. JPG http: //www. crazyscuba. com/misc_images/RIMG 0121 Fl atworm. Crop. jpg

Nematoda - roundworms http: //collections. ic. gc. ca/potato/ scitech/nematodes. jpg

Nematoda: Heartworm http: //www. greatlakesbcrescue. org/Health. NTraining/heartworms. JPG http: //www. dukkha. org/images/heartworm. jpg

Mollusca http: //students. umf. maine. edu/~hustontf/ squid. jpg http: //www. wallpaperbase. com/wallpape rs/animals/snail_1. jpg

Annelida – segmented worms http: //www. abc. net. au/reslib/2007 04/r 138958_475480. jpg http: //www. york. ac. uk/org/ciec/Caringforthe. Environment. 29. 4. 03/Ex xon/Food%20 Chain%20 images/Exxon. Pics. Large/Earthworms. jpg

Bristle Worm http: //i 30. photobucket. com/albums/c 317/greenbaja 73/Bristle_worm. jpg

Arthropoda http: //xyala. cap. ed. ac. uk/Neglected. Genomes/ARTHRO PODA/images/AMC. jpg http: //flatrock. org. nz/topics/animals/assets/ black_widow_spider. jpg

http: //dereila. ca/dereilaimages/sowbugs. jpg

Arthropoda - CLASS DIPLOPODA GIANT MILLIPEDE http: //umdgrb. umd. edu/pretz/images/millipede 8. jpg

Echinodermata http: //brown. edu/Administration/News_Bureau/2006 -07/06 -052 b. jpg

Echinodermata http: //www. marietta. edu/~biol/biomes/images/shores/piaster_ochraceus_4740_A 80_800. jpg

http: //www. tankedup-imaging. com/images/prickly_red_sea_cucumber. jpg http: //animals. nationalgeographic. com/staticfiles/NGS/Shared/Static. Files/animals /images/primary/sea-cucumber-ga. jpg Sea Cucumbers http: //www. bubblevision. com/albums/burma-banks/images/sea-cucumber. jpg