Biology I

(Chapter 30-Kingdom Animalia)

Terms : closed circulatory system gizzard

mantle nephridia

nocturnal open circulatory system

4 main body types of animals

I. Acoelomate

A. 2 germ layer acoelomate

n ectoderm and endoderm touch

n least complicated(sponges, cnidarians)

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B. 3 germ layer acoelomate

n ectoderm, mesoderm, and endoderm all touching (flat worms)

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II. Pseudocoelomate

n ectoderm and mesoderm touch, then a space, then endoderm and coelom

( round worms)

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III. Coelomate

n most complex body plan

n ectoderm touching mesoderm, a false space, then mesoderm touching

endoderm, (mesoderm bridges suspending inner layers)

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I. Kingdom Animalia

A. Sub Kingdom Eumetazoa

1. Phylum Platyhelminthes -“flat worms”

- flat worm characteristics

n acoelomate body type

n bilateral symmetry

n cephalization- This allows free movements, greater response to environment, and gives the ability to seek prey.

n free living and parasitic

- These structures help parasites:

1. tegument - thick covering of cells

2. cuticle - secreted layer that protects worm

n no respiratory system

n no circulatory system

a. Class Turbellaria

n free living

n fresh water

n used a lot as lab specimens

genus : Dugesia - planarian

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n body -

- acoelomate

- anterior end “arrow” shape

- covered by cilia

- cephalization

n eye spots- monitor light

n cilia - touch

n taste

n smell

- memory controlled by chemicals

n can gain memory by eating other planarians

n movement -

- swims by ungulating over a layer of mucus

- cilia also help gliding over mucus.

n digestion -

- scavenger

- feeds on protozoa

- sucks food in through pharynx

- undigested food exits mouth

n excretion -

n flame cells

- eliminate excess water and chemicals

n excretory pore

- duct that allows passage of wastes out of flame cells

n Nervous system -

- ganglion(a bundle of nerve tissue) = primitive brain at anterior end

n Muscular system - 3 types of muscles help them swim

1. circular muscles - lengthens and thins body

2. longitudinal muscles - shortens and thickens body

3. oblique muscles - allows the body to twist

n Reproductive system -

- regenerate = asexually

- hermaphroditic

- conjugation = sexually

b. Class Trematoda

- flukes -

n characteristics

- parasitic- endoparasitic(in you) and ectoparasitic(on you)

- leaf shaped

- 2 suckers- one at each end

- hermaphroditic

2 types of flukes

1. Sheep liver fluke

n adult flukes live in sheep liver

n mate in liver

n eggs passed out of sheep in feces and end up in water

n eggs hatch in water and become larvae

n larvae invade a snail and sexually multiply

n mature flukes leave snail within 8 hours and climb on grass and form a cyst

n sheep eat grass with cysts on them and cycle begins again

cyst - hard protective covering to survive harsh conditions

2. Human blood fluke (Schistosoma)

n People can get this in tropical areas by swimming or drinking

water.

n the vector into the humans is also the snail.

Schistosomiasis- a sickness caused by the human blood fluke

symptoms: - lung infection

- internal bleeding

- tissue decay

- death

c. Class Cestoda

- tapeworms -

characteristics

n parasitic - (intestine)

- humans can host 7 different varities

n tegument

n no sense organs

n eat by absorb

n long slender bodies

-anterior end

n hooks (on scolex head)

n suckers (on scolex head)

to hold on to host

n rest of body hangs freely

- proglottid

body segments

n proglottids house both male and female reproductive structures

n egg develop here, so the proglottid eventually becomes full with eggs

n The proglottids at the “tail” end fall off and leave the animal with its feces.

How do humans get tapeworms?

n by eating meat infected with cysts

n cysts may last for 50 years

n an adult worm may make 25,000 eggs per. body segment per day

2. Phylum Nematoda

- nematodes -

characteristics-

n tegument and cuticle

n long flexible bodies

n one way digestive tract : (mouth>>digestive tube>>anus)

n plant and animal parasites

n pseudocoelome body plan

n 1mm>>60 inches long

3 types of nematode parasites

1. ROUND WORMS

a. Ascaris - round worm

n found in intestines of pig, dog, cow, man

- humans may host 50 different varieties of roundworms.

n contaminates food and water

n female can produce 200,000 eggs a day

b. Trichinella - roundworm

n found in pork, bear, beef, venison

n infected by uncooked or improperly cooked meat

n causes trichinosis in humans

- symptoms are pain and stiffness of muscles

n The larvae travel through your blood and end up boring into your muscles where they encyst. If the meat is not eaten to release them to continue their lifecycle, they die inside the muscle of host causing severe pain from the decomposing toxins.

n two ways to kill the Trichenella worm

1. cook meat all the way through

2. freeze meat

2. HOOKWORMS

Necator and Ancyclostoma - hookworm

n contracted when larvae bore through the soles of feet when stepped on

n larvae enter blood system, migrate to lungs, are coughed up, swallowed and end up in intestines where they absorb predigested material.

Why is necator a big problem in the tropic and the southern United States?

3. PINWORMS

Enterobus - pinworm

n contracted through infected household pets

- The adults live in the intestine, at night

they deposit their eggs on the outside of anus

they are transmitted to other humans through air or contact.(scratching, towels, carpet, bedding)

3. Phylum Mollusca

(snail, clam, chitin, scallops, squid, octopi )

n slow to fast moving

n fresh and marine water environments and terrestrial

n shells and no shells

n bilateral symmetry

n coelom body type

n muscular foot (some)

n mantle (some)

n free swimming larvae

n radula - helps capture prey

Four classes of Mollusks

a. Class Polyplacophora

- (chitins)

- prehestoric

- armored shell

- large foot

b. Class Bivalvia

- (clams, oysters, scallops, muscles)

- 2 shells

- sessile

- mantle = shell secreating layer (pearl layer)

c. Class Cephalopoda

- (squid, nautilus, octopus)

- (largest invertebrate in the world = giant squid)

- intelligent

- “foot” evolved into tentacles

- hard horny jaws - rip and shred

- well developed eyes

- well developed nervous system

d. Class Gastropoda

- (snail, slug, conches)

- 50 % are terrestrial

4. Phylum Rhyncocoela

- ribbon worms -

n mainly marine

n highly colored bodies

5. Phylum Rotifera

- rotifers -

n crown of cilia

6. Phylum Loricifera

n found in 1983

n live between grains of sand in the sea

7. Phylum Bryozoa

- bryozoans -

n recently moved to Kingdom Protista

8. Phylum Brachiopoda

- lamp shells -

n look similar to clams

9. Phylum Phoronida

- tube dwelling worms -

n 500 tentacles ring mouth area

10. Phylum Annelida

-segmented worms-

- (earth worm, leech)

n bilateral symmetry

n brain = cerebral ganglion

n well developed circulatory system

n complete one-way digestive tract

n coelom body style

metamerism = body divided into many segments (some segments may fuse)

septa - separate segments

setae = hair-like bristles

n found on ventral surface

n used for locomotion

n The earthworm has 2 on each lateral ventral surface

Three classes of Annelids

a. Class Polychaeta

- marine worms - bristle worm ( p. 746 )

n have antennae

n have parapodia- paddle-like flaps to help them “swim” through water

b. Class Hirudinea

- leeches-

n do not have setae

n have suckers at both ends of body

n fresh water habitats

n ectoparasitic

- useful in medicine

Hirudo medicinalis = medical leech:

secretes:

n anaesthetic

n anticoagulant

c. Class Oligochaeta

- earthworms -

n 3100 different species

n habitats - fresh water, marine, terrestrial

n over 100 segments

prostomium = first segment -- lip

Clitellum = fused body segments

cephalization - sense organs concentrated at anterior end

good for burrowing

n muscular system well developed

- 3 types of muscles

n longitudinal muscles

n circular muscles

n oblique muscles

Excretory System

nephridia- organs that expel liquid waste products

castings- solid waste products excreted from anus

Digestive System

nutrition = eats organic particles in soil

basic organs of digestion ( in sequence )

1. mouth

2. pharynx

3. esophagus

4. crop……stores food

5. gizzard….. grinds up food; thick muscular organ

6. intestine

7. anus

Respiratory System

n they breathe through their moist skin

- the skin must be moist for the oxygen to be able to diffuse into the

worm

Circulatory System

n 5 aortic arches- “hearts”

n dorsal blood vessel

- takes blood from posterior to anterior end

n ventral blood vessel

- takes blood from anterior to posterior end

Nervous System

ganglion- nerves fused at the anterior end to form a “brain”

n 2 nerves extend from ganglion and fuse to form the ventral

nerve cord

- the ventral nerve cord is sensitive to:

n touch, vibration, temperature, chemicals, light, moisture ( a red light attracts worms )

Reproductive System

hermaphroditic- each worm has a complete set of male and female

reproductive parts

clitellum- fused body segments

n forms storage area for eggs and sperm

fertilization-

n 2 worms line up in opposite directions

n sperm is stored in seminal recepticles and is exchanged

n as the eggs are laid, the sperm of the “partner” worm is released to fertilize eggs.

n the clitellum makes a slime ring that covers and protects the fertilized eggs(and later young) in the soil.