The Animal Kingdom

Welcome to your kingdom!

Where we’ve been…and where we’re headed….

What is an animal?

• Multicellular, eukaryotic heterotrophs

• They lack cell walls: their bodies are held together by other proteins like collagen and cell junctions that hold the cells together to provide an animal strength in form

• Some animals also have a skeleton:– Exoskeletons (on the outside) made of chitin

(these will need to be shed in order for the animal to grow) ex. Shells of insects, crabs, spiders

– Endoskeletons (on the inside) made of bone

– Hydrostatic skeletons: water or another fluid provides pressure pushing out from the inside of the animal to provide support (like a water balloon)

• Animals are capable of moving from one place to another– This is made possible by the coordination of

two “new” types of tissue: nerve and muscle

Of course there are some exceptions: sedentary (or sessile) animals have no movement; they remain fixed in one location

• Most biologists agree that the animal kingdom can be traced back to one common ancestor about 700 million years ago

This ancestor was most likely a protozoan.

One hypothesis suggests that this flagellated protist formed a single layer, hollow ball of cells. Eventually, some of these cells began to specialize creating two or more layers of cells

http://www.microscopy-uk.org.uk/mag/wimsmall/cilidr.html

The opening to the digestive cavity (the blastopore) becomes the mouth

Animal embryos form layers

• Ectoderm: forms the outer covering and nervous system

• Mesoderm: forms all of the other stuff in between• Endoderm: lines the digestive tract and makes the

accessory organsIf an animal has all three layers:

Triploblastic (3 layers)Only two layers:

Diploblastic (2 layers)

Animal Symmetry

1. Some animals lack symmetry all together

(they are asymmetrical)

Animal Symmetry

2. Others have radial symmetry (like a flower pot)

No matter how you would cut the animal vertically through the body, all of the wedges would appear the same

Animal Symmetry

3. While others have bilateral symmetry (two-sided symmetry)

Terms associated with bilateral symmetry

• Dorsal• Ventral• Anterior• Posteror

Phylum Porifera

The Sponges

Basic body plan of sponges

Only one cell layer; no true tissues

Almost everything is accomplished by diffusion

Glenn and Martha Vargas© 2004 California Academy of Sciences

Vase sponge

Eugene Weber© 2001 California Academy of Sciences

The Glass Sponge

This is the skeleton only; all of the other cells have disintegrated.

Phylum Cnidaria(The Cnidarians)

• Sea Anemones

• Hydra

• Coral

• Jellyfish

Basic Body Plan

• *Two body forms: polyp and medusa

• *Stinging tentacles surround the mouth

• Only two cell layers: epidermis and gastrodermis

• First animals to have a mouth

• Members can reproduce sexually as well as asexually (budding)

Jellyfish Life Cycle

• Note the change between polyp and medusa

Gerald and Buff Corsi © 1999 California Academy of Sciences

Gerald and Buff Corsi© 2002 California Academy of Sciences

Gerald and Buff Corsi© 2002 California Academy of

Sciences

© 2003 Dr. Peter Weish

Glenn and Martha Vargas © 2004 California Academy of Sciences

“Artic Jelly” washed up on shore

Artic Jelly…up close and personal…

E. Eugenia Patten© 2001 California Academy of Sciences

Dr. Robert Thomas and Margaret Orr© 2004 California Academy of Sciences

Gerald and Buff Corsi© 1999 California Academy of Sciences

Gerald and Buff Corsi© 1999 California Academy of

Sciences

Coral Polyps

Eugene Weber© 2001 California Academy of Sciences

Glenn and Martha Vargas© 2004 California Academy of Sciences

Beatrice F. Howitt© 2002 California Academy of Sciences

Portuguese Man-of-War; a colonial cnidarian

Gerald and Buff Corsi © 1999 California Academy of Sciences

Phylum Ctenphora: (“Comb jellies”) Beroe species

Phylum Platyhelminthes(the flatworms)

• Tapeworms

• Flukes

• Planaria

Phylum Platyhelminthes: the flatworms Planaria

Planaria splitting…

General Characteristics of the flatworms

• bilateral symmetry• three cell layers• possess a ganglia (forerunner of a brain)• sensory receptors• pharynx that leads to digestive cavity (but

still no anus)• flame cells help excrete metabolic wastes

(their version of urine)

Planaria body plan

The Flame Cell

Tapeworms…..

Tapeworm scolex showing hooks and suckers

Scolex of a rat tapeworm

Proglottids

Pork Tapeworm Life Cycle

Fish Tapeworm Life Cycle

Dog tape worm

Marine flatworm

                                                                           

Nothing beyond this point on the final!!!!

Phylum Nematoda (the roundworms)

• Tube-within-a tube body plan

• WOW!!! An anus!!!

• They have a hydrostatic skeleton

• Reproduce only sexually

• Many are parasites

Phylum Arthropoda

• Bilateral symmetry

• Breath by using gills

• Well developed nervous system

• Most have shells

• All have a mantle: a fleshy fold of tissue that surrounds the internal organs

• Most have a shell

Class Gastropoda(the gastropods-snails, slugs)

• Name means “stomach foot”

• Most have one shell (like snails)

• Feed with a radula