KINGDOM ANIMALIA

I. General Characteristics

Multi-cellular Eukaryotes Consumers (Heterotrophs) Motile Complex organ system Reproduces sexually Two divisions:

Invertebrates & Vertebrates

Animals have Symmetry Symmetry

Balance in proportions of an object or organism

Asymmetry Irregular body plan

Radial symmetry Body can be divided along any

plane, through the central axis, into roughly equal halves

Bilateral symmetry Body can be divided down its length

into similar right and left halves that form mirror images of one another

Body Plans Coelom

Body cavity surrounded by a mesoderm

Acoelomate Three cell layers with a digestive

tract but no body cavitiesPseudocoelomate

Fluid-filled body cavity partly lined with mesoderm

INVERTEBRATES Animals without a backbone

Porifera Cnidarians Platyhelminthes Nematoda Annelida Mollusca Arthropoda Echinodermata

Invertebrates

II. Phylum Porifera

A. Example: sponges

B. Word means “pore bearing”

C. Asymmetry

D. Natural sponges: nonliving material that remains after decay

E. Sessile: live attached to a surface

F. Do not have nerve cells or tissue

G. Filter feeders: pump water in and out and feed on the organic material in water

H. Many are hermaphrodites: able to produce male and female gametes – an advantage for sessile organisms

I. Can reassemble when fragmented

III. Phylum Cnidaria

A. Examples: coral, jellyfish, sea anemone

B. Cnidocytes: cells that contain stinging poisonous barbs with which they paralyze prey

C. Radial symmetry

D. Two body forms

1. polyp: sessile, tentacles up – coral, hydra

2. medusa: free swimming, tentacles down – jellyfish

E. Digestive body cavity surrounded by two layers of cells

F. Sexual or asexual reproduction – hydra reproduces by budding

G. Coral reefs build up and are important ocean habitats

IV. Phylum Platyhelminthes

A. Examples: flatworms, tapeworms, flukes

B. Many parasitic forms - cause many diseases of people and livestock

C. Bilateral symmetry and cephalization (concentration of sensory organs and nervous tissue in the head)

D. One digestive opening (pharynx) to take in food and release waste – most don’t need complex digestive systems because food has already been digested by their host

E. Most are hermaphroditic, some can regenerate lost body parts

V. Phylum Nematoda

A. Examples: roundworms (pinworms, hookworms)

B. Many are microscopic

C. Two digestive openings: mouth and anus – food moves only one way

D. Only sexual reproduction; usually separate sexes; no regeneration

E. Most are free-living, many are parasitic – you can be infected by consuming contaminated food/water or by being bitten by insects

VII. Phylum Annelida

A. Examples: segmented worms, earthworms, leeches

B. Body divided into many segments

C. Complete digestive tract

1. pharynx

2. esophagus

3. crop

4. gizzard

5. intestine

6. anus

D. Closed circulatory system: blood stays within vessels1. main vein is dorsal (upper/back

side)

2. 5 aortic arches: function as simple hearts

F. Earthworm is hermaphroditic; others have separate sexes

G. Earthworms are important in the soil ecosystem– provide passageways for plant roots and water

VIII. Phylum Mollusca

A. Examples: snails, clams, octopus, squid

B. Mollusks and annelids have a true coelom (body cavity)

C. Characteristics:

1. muscular foot: used for motion or attachment – the foot may be modified into tentacles

2. mantle: soft, outer layer of body

3. visceral mass: contains most of the internal organs

4. gills or lungs: located in the mantle cavity

D. Main groups of mollusks

1. gastropods (“stomach-footed”)

a. univalves: one shell, breathe with lungs; example: snail

b. bivalves: two shells, breathe with gills; example: clam

2. cephalopods (“head-footed”)

- foot is modified into tentacles, breathe with gills;

examples: octopus, squid

E. Sexual reproduction: most have separate sexes, some are hermaphrodites

F. Most have an open circulatory system (blood is contained within vessels that empty into sinus cavities). Cephalopods have a closed system (blood remains within vessels).

G. Most mollusks are marine, but some live in fresh water or on land

IX. Phylum ArthropodaA. Largest phylum – found in almost all

places on earth

B. Characteristics:

1. exoskeleton

a. Outside the body

b. Very good protection

c. Does not grow, so it must be shed periodically (molting)

2. paired, jointed appendages (body extensions)

3. segmentation

4. open circulatory system

5. ventral (lower/belly side) nerve cord

C. Classified based on number and structure of body segments and appendages

D. Centipedes and Millipedes

1. most primitive arthropods

2. obvious segmentation

3. Centipedes (Class Chilopoda)

a. one pair of legs per segment

b. poisonous fangs for killing prey

c. long antennae

4. Millipedes (Class Diplopoda)

a. two pairs of legs per segment

b. one pair of short antennae

c. usually harmless vegetarians

E. Crustaceans (Class Crustacea)

1. examples: lobster, crayfish, shrimp

2. most are marine

3. two body regions:

a. cephalothorax

b. abdomen (divided into 7 segments)

4. two short pair of antennae (1 long, 1 short pair)

5. swimmerets: appendages on the abdomen used for swimming

6. breathe by gills attached to the swimmerets

7. one pair of large claws

8. 4 pairs of walking legs

F. Arachnids (Class Arachnida)

1. examples: spiders, ticks, mites, scorpions

2. two body regions:a. cephalothoraxb. abdomen: no appendages on abdomen

3. no antennae4. simple eyes5. 4 pairs of walking legs6. mouthparts modified as fangs (chelicerae) to stab prey and suck out body fluids7. book lungs (gills modified for breathing on land)

G. Insects (Class Insecta)

1. over 75% of all animal species

2. first animals to develop flight

3. Characteristics:

a. three body regions

1. head

2. thorax (with 3 pairs of legs)

3. abdomen

b. usually 1 or 2 pairs of wings

c. 1 pair of antennae

d. compound eyes

e. respiration through a system of tubes called tracheae

4. metamorphosis: a series of changes during which young insects

develop into adults

a. some insects do not carry on metamorphosis (silverfish)

b. incomplete (gradual) metamorphosis

(grasshopper)

1. egg

2. nymph (look like adults, but

smaller, with no wings or reproductive

organs)

3. adult

c. complete metamorphosis (butterflies, bees)

1. egg

2. larva (caterpillar)

3. pupa

4. adult

X. Phylum Echinodermata

A. Name means “spiny skin”

B. Marine environment

C. Radial symmetry – body parts usually in multiples of 5

1. larvae have bilateral symmetry

2. have a fairly close relationship to vertebrates

D. Water vascular system

1. system of internal tubes

2. carries out functions of circulation, respiration, and movement

E. Tube feet

1. act like living suction cups

2. help in movement and feeding

F. Examples: sea urchins, sand dollars, starfish

XI. Comparing Invertebrates

A. Specialized cells, tissues, and organs

1. Sponges and Cnidarians: little internal specialization

2. Flatworms: simple organs

3. More complex invertebrates: organ systems

B. Body symmetry

1. sponges: no symmetry

2. cnidarians and echinoderms: radial symmetry

3. all other phyla: bilateral symmetry

C. Cephalization: concentration of sense organs and nerve cells in the front of the organism

1. sponges: no nerve tissue

2. cnidarians: nerve net

3. worms and arthropods: groups of nerves called ganglia

4. mollusks: brain

D. Coelom formation: body cavity formation

1. sponges and cnidarians: two cell layers with a jellylike material between them

2. other invertebrates have 3 cell layers

3. types of coeloms:

a. flatworms: no body cavity (acoelomates)

b. roundworms: body cavity partially lined with mesoderm

(pseudocoelomates)

c. other invertebrates: body cavity completely lined with mesoderm (coelomates)

F. Feeding and digestion

1. intracellular digestion: food is broken down inside cells (lower animals)

2. extracellular digestion: food is digested and then enters the

cells – enables digestion of larger pieces of food (higher invertebrates)

G. Respiration

1. diffusion through skin: many worms

2. gills: aquatic invertebrates (many mollusks and arthropods)

3. mantle cavity: snails

4. book lungs: spiders

5. tracheal tubes: many insects

H. Circulation1. open circulatory system: blood

does not stay within vessels, empties into sinuses; examples: arthropods, most mollusks

2. closed circulatory system: blood remains within vessels; examples: annelids, some mollusks

I. Movement and support

1. hydrostatic skeleton: fluid-filled body cavity supports the

muscles; examples: annelids, jellyfish

2. exoskeleton: skeleton is outside the body; examples:

arthropods

3. endoskeleton: located inside the body; examples: vertebrates

J. Reproduction

1. all animals reproduce sexually, some may also reproduce asexually

2. external fertilization: (usually in water) eggs and sperm are released into the surrounding environment

3. internal fertilization: (usually on land) eggs are fertilized inside the body of the female