Team Two!!!

Platyhelminthes (flatworms)

Rotifera (rotifers) and Nematoda (round worms)

Nemertea (ribbon worms) and Lophophorate

Platyhelminthes

Have bilateral symmetry Can be free living or

parasitic which absorb nutrients from a host

Have 3 germ layers and are acoelmate (lacking a cavity between gut and outer wall)

Are protostomes Move by using cilia or by

contracting their muscles Flatworm

Platyhelminthes

Free living platyhelminthesreproduce asexually by fission and parasitic platyhelminthes reproduce sexually and self fertilize

The embryo of tapeworms and other parasitic worms are called scolex

Tapeworm

Platyhelminthes

-Trichinella Life cycle

Schistosoma Life Cycle-

Platyhelminthes Specalized Tissues Platyhelminthes have a ventral nerve cord

• have eye spots that detect the intensity of light

• have ganglia, which is a mass of nerve cell bodies ( resembles a brain)

• have a gastrovascular cavity called a pharynx- which is a single opening used as both a mouth and anus

Examples are tapeworms, flukes, Dugesia,

Dugesia tigrina

Phylum Rotifera

About 1,800 species Are tiny animals that mainly inhabit fresh water,

although some live in the sea or in damp soil. Range in size from about 0.05 to 2 mm (much smaller

compared to other protists.) Have bilateral symmetry and are truly multicellular. “Rotifer,” derived from Latin, means “wheel-bearer”—a

reference to the crown cilia that draws a vortex of water into the mouth.

Examples: Rotaria, Philodina, Keratella, Brachionus, and Polyarthra.

Phylum Rotifera

Have specialized organ systems—including a complete digestive tract: a digestive tube with a separate mouth and anus.

Perform a type of reproduction called parthenogenesis: females producing more females from unfertilized eggs.

Phylum Rotifera

Are pseudocoelomate animals—they have a cavity that is not completely lined by mesoderm-derived tissue.

The fluid in the pseudocoelom serves as a hydrostatic skeleton and as a medium for the internal transport of nutrients and waste.

Rotifers may be: -free swimming -able to move by inchworming along the substrates -sessile, living inside tubes or gelatinous holdfasts. Video: http://www.youtube.com/watch?v=YF8OJt_pujc

Phylum Nematoda Roundworms About 90,000 known species. Many are free-living soil dwellers that help decompose and recycle

nutrients. Have bilateral symmetry. Examples: whipworms, hookworms, pinworms, ascarids, and filarids.

Nematoda

Phylum Nematoda Have a complete digestive tract: a

digestive tube with a separate mouth and anus.

Covered by a tough, transparent cuticle—the exoskeleton of an arthropod, consisting of layers of protein and chitin.

The muscles of nematodes are all longitudinal, and their contraction produces a thrashing motion. This and the cuticle help nematodas to move.

Are pseudocoelomate animals—they have a cavity that is not completely lined by mesoderm-derived tissue.

Phylum Nematoda

Reproduction is usually sexual—females are generally larger than males.

Fertilization is internal, and a female can deposit 100,000 or more fertilized eggs per day.

The zygotes of most species are resistant cells capable of living in harsh conditions.

Hookworm

Phylum Rotifera and Nematoda

Are both eumetazoa—they have closely functioning cells organized into tissues.

They are triploblastic (contain three germ layers.) These three layers (ectoderm, mesoderm, and endoderm) develop into various organs during embryonic development.

There is a progressively greater increase in nerve tissue concentration at the anterior end (head.)

Both have a complete digestive tract.

Nemertea Many live in water, so they

can swim quite well. Has a complete digestive

tract and a closed circulatory system. (blood contained in vessels)

However, they have no heart, the blood is propelled by muscle squeezing vessels.

Baseodiscus delineatus

-The phylum has bilateral symmetry

-Has 3 germ layers

-Has a primitive coelom.

-They use the coelom (filled with fluid) to propel themselves through the water.

Nemertea (cont.)

Life:• As a juvenile the

nemertea lives in the exoskeleton of a crab.

• The size increases as the crab’s shell increases.

• They are predators and will either actively pursue their prey or sit and wait for it.

Cerebratulus

Nemertea (cont.)

Examples:• Malacobdella lives

parasitically in molluscs

Tubulanus rhabdotus

Deep water ribbon worm.

The proboscis apparatus is used as a means of catching food. It wraps around the food and draws it in.

Nemertea (cont.)

Different types of Nemertea have different colors, however their colors change depending on where they are. (caves or exposed).

Commonly called ribbon worms.

The largest type of Nemertea that has been found, Lineus longissimus, stretched 30 m long!

Normally 10mm-100cm long.

Removal of Guinea Worm

http://www.youtube.com/watch?v=mUz9gqLmyQ0

Lophophorate

Combines three phyla: Bryozoans, Phoronids, Brachiopods.

All three have a lophophore: a horseshoe-shaped fold of the body that has cilia, surrounding the mouth.

The three phyla also share a U-shaped digestive tract and have no head.

Bryozoan

Lophophorate (cont.)

They have true coeloms, lined fully with mesoderm. 3 germ layers.

Bryozoans and brachiopods are sessile while phoronids live buried in the sand.

Development:

• Bryozoans- larval; has radial clevage at first, and then spiral.

Placed closer to protostomes, however in embryonic development they resemble deuterostomes.

Lophophorate (cont.)

Costazia costazi, bryozoan

Fresh water Bryozoan with lophophore extended.

Phoronopsis californica- phoronid Phoronis hippocrepia -

phoronid

Onniella meeki- Brachiopod

Lophophorate (cont.)

Bryozoans help build reefs

Brachiopods, resemble clams.

Phoronids- tube-dwelling marine worms. Tubes made of chitin!

Seem to be either asymmetrical or bilateral.

Review Game: Platyhelminthes

What type of symmetry do Platyhelminthes have?

How do Platyhelminthes move? How do parasitic platyhelminthes

reproduce? What is the function of eye spots?

Answers: Platyhelminthes

What type of symmetry do Platyhelminthes have? Bilateral Symmetry

How do Platyhelminthes move? By using cilia or by contracting their muscles.

How do parasitic platyhelminthes reproduce? They reproduce sexually and self fertilize.

What is the function of eye spots? They detect the intensity of light.

Review Game: Rotifera and Nematoda

What type of symmetry do the phylum Rotifera and phylum Nematoda share?

What is a complete digestive tract? What type of reproduction do Rotifers

perform? Which phylum has a hydrostatic skeleton?

Answers: Rotifera and Nematoda

What type of symmetry do the phylum Rotifera and phylum Nematoda share? Bilateral Symmetry

What is a complete digestive tract? A digestive tube with a separate mouth and anus.

What type of reproduction do Rotifers perform? Parthenogenesis

Which phylum has a hydrostatic skeleton? Rotifera

Review Game: Nemertea and Lophophorate

What are the three phyla under lophophorate? And what do they look like?

What is a proboscis apparatus? Where do nemerteas grow up? What is the function of Bryozoans?

Answers: Nemertea and Lophophorate

What are the three phyla under lophophorate? Bryozoans, Phoronids, Brachiopods And what do they look like? All three have a lophophore.

What is a proboscis apparatus? It is used as a means of catching food. It wraps around the food and draws it in.

Where do nemerteas grow up? In the exoskeleton of a crab.

What is the function of Bryozoans? They help build reefs.

~THE END~