Chapter 25- Intro to Animals

I. Characteristics

A. Kingdom Anamalia1. Multicellular2. heterotrophic3. eukaryotic4. lack cell walls

B. Types of Animals1. Invertebrates

a. Includes all animals that lack a backbone or vertebral column

b. Sea stars, worms, jellyfish, squid, insectsc. 33 phyla

2. Chordatesa. Less than 5%b. Phylum Chordatac. 4 common characteristics that must be present

sometime in life- pg. 731» Hollow dorsal nerve cord» Notochord- long supporting rod that runs under

the nerve cord» A tail that extends beyond the anus» Pharyngeal pouches- structures in the throat

regiond. Chordates with backbones are called vertebrates» fish, amphibians, reptiles, birds, mammals

C. Survival in the Animal Kingdom1. All animals have the ability to maintain homeostasis

a. Use the nervous system to gather & sense information, interpret the information and stimulate muscles to respond

b. Maintain and distribute oxygen & nutrients (respiratory, circulatory & digestive systems all work together)

c. Eliminate carbon dioxide & wasted. Reproduce e. Maintained by feedback inhibition or negative feedback

II. Body Plan

A. Symmetry1. Radial symmetry- many planes of symmetry (circle)2. Bilateral symmetry

a. most successfulb. 1 plane of symmetryc. Definite front and back side, & head and tail end

3. Asymmetry – no plane of symmetry

B. Germ layers1. Endoderm

a. Inner most layerb. Lines the digestive tract & respiratory system

2. Mesoderma. Middle layerb. Gives rise to the muscles and the circulatory,

reproductive & excretory system3. Ectoderm

a. Outer most layerb. Produces sense organs, nerves and outer layer of

skin

C. Body Cavity- pg. 7381. Coelomates

a. Have a true coelom – a body cavity that develops within mesoderm tissue and is completely lined

b. Example: earthworm2. Pseudocoelomates

a. Have a pseudocoelom- partially lined body cavityb. Example: roundworm

3. Acoelomatea. No body cavityb. Example: flat worm

D. Patterns of Embryological development1. Fertilized egg is a zygote2. As the zygote grows during mitosis, it develops into a

structure called a blastula3. As the digestive tract forms in the blastula, there is

initially a single opening called a blastopore4. If the organism is a protostome, the blastopore

becomes the mouth5. If the organism is a deuterostome, the blastopore

becomes the anus

E. Segmentation1. Body parts that are repeated in animals with bilateral

symmetry2. Ex. Segments of the earthworm, vertebrae in humans

F. Cephalization: getting a head1. Animals with bilateral symmetry usually have a head2. This happens when the concentration of sense organs

and nerve cells increase at the anterior end3. Animals usually move “head first”

G. Limb Formation1. External appendages that are jointed2. Ex. Wings, flippers, arms, leg

III. Invertebrate & vertebrate Phyla

• Phylum Porifera– Specialized cells– Asymmetrical– No germ layers– No body cavity– No segmentation– No head– Sponges are the most ancient members of the

animal kingdom

• Phylum Cnidaria– Specialized cells, tissues, specialized stinging cells– Radial Symmetry– 2 germ layers– Acoelom– No segmentation– No head– Hydras, coral, jellyfish, sea fans, sea anemones

• Phylum Platyhelminthes– Specialized cells, tissues, organs– Bilateral symmetry– 3 germ layers– Acoelom– Protostome– No segmentation– Cephalization – Flatworms

• Phylum Nematoda– Specialized cell, tissues, organs– Bilateral symmetry– 3 germ layers– Pseudocoelom– Protostome– No segmentation– Cephalization – Round worms

• Phylum Annelida– Specialized cells, tissues, organs– Bilateral symmetry– 3 germ layers– True coelom– Protostome– Segmentation present– Cephalization– Earthworms, leeches, marine worms

• Phylum Mollusca– Specialized cells, tissues, organs– Bilateral symmetry– 3 germ layers– True coelom– Protostome, motile larval stage called a trochophore– No segmentation– Cephalization– Snails, slugs, clams, squid, octopi

• Phylum Arthropoda– Specialized cells, tissues, organs– Bilateral symmetry– 3 germ layers– True coelom– Protostome– Segmentation present, jointed appendages– Cephalization– Insects, spiders, centipedes, crustaceans

• Phylum Echinodermata– Specialized cells, tissues, organs– 5 part radial symmetry (as adults)– 3 germ layers– True coelom– Deuterostome– No segmentation– Cephalization absent (as adults)– Sea star, sea urchins, sand dollars

• Phylum Chordata– Specialized cells, tissues, organs– Bilateral symmetry– 3 germ layers– True coelom– Deuterostome– Segmentation present– Cephalization– Tunicates, lancelets, vertebrates