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

AsymmetryBilateral symmetry

Radial symmetry

http://www.misterteacher.com/orange%20and%20black%20butterfly.jpg

http://www.hope.edu/academic/art/past/VanderBurgh/mapleave.rose2.jpg http://daphne.palomar.edu/design/asymm/

jd01asym.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

Fig. 23-2

(a) Radial symmetry (b) Bilateral symmetry

central axis

anterior

posterior

plane ofsymmetry

plane ofsymmetry

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. Vertebrates* No vertebral column * Vertebral column* Often have exoskeletons * Endoskeletons

Invertebrates

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

http://www.richard-seaman.com/Underwater/Belize/StillLifes/TubeSpongesThreeOrange.jpg

PHYLUM PORIFERATHE SPONGES

http://www.biology4kids.com/misc/photos/cnidaria1.jpg

Cnidaria

http://www.sydneyaquarium.com.au/Downloads/INT/Wallpaper_1024x768_WaratahAnemone.jpg

Cnidaria – Polyp body form

http://www.luc.edu/faculty/jreymon/biolab/planaria.jpg

Planaria

Platyhelminthes - flatworms

http://members.aol.com/uwphotohi/Images/flatworm.JPG

http://www.crazyscuba.com/misc_images/RIMG0121FlatwormCrop.jpg

Marine Flatworms

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

Nematoda - roundworms

http://www.greatlakesbcrescue.org/HealthNTraining/heartworms.JPG

http://www.dukkha.org/images/heartworm.jpg

Nematoda:Heartworm

Mollusca

http://students.umf.maine.edu/~hustontf/squid.jpg

http://www.wallpaperbase.com/wallpapers/animals/snail/snail_1.jpg

http://www.york.ac.uk/org/ciec/CaringfortheEnvironment.29.4.03/Exxon/Food%20Chain%20images/ExxonPicsLarge/Earthworms.jpg

Annelida – segmented worms

http://www.abc.net.au/reslib/200704/r138958_475480.jpg

Bristle

Worm

http://i30.photobucket.com/albums/c317/greenbaja73/Bristle_worm.jpg

Arthropoda

http://xyala.cap.ed.ac.uk/NeglectedGenomes/ARTHROPODA/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/millipede8.jpg

Echinodermata

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

Echinodermata

http://www.marietta.edu/~biol/biomes/images/shores/piaster_ochraceus_4740_A80_800.jpg

http://www.bubblevision.com/albums/burma-banks/images/sea-cucumber.jpg

http://www.tankedup-imaging.com/images/prickly_red_sea_cucumber.jpg http://animals.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/animals/images/primary/sea-cucumber-ga.jpg

Sea Cucumbers